ISO/DTS 80004-12

• Abstract:

  ISO/TS 80004-12:2016 lists terms and definitions relevant to quantum phenomena in nanotechnologies. All of these terms are important for nanotechnologies, but it is to be noted that many of them are not exclusively relevant to the nanoscale and can also be used to some extent to refer to larger scales. The list of terms presented does not claim to provide exhaustive coverage of the whole spectrum of quantum concepts and phenomena in nanotechnology. It covers important phenomena as acknowledged by many stakeholders from academia, industry, etc. ISO/TS 80004-12:2016 is intended to facilitate communication between organizations and individuals in industry and those who interact with them.

• Status: Not Published
• ICS: 01.040.07 - Natural and applied sciences (Vocabularies)
• ICS: 07.120 - Nanotechnologies
• Technical Committee: ISO/TC 229 - Nanotechnologies
• Drafting Committee: ISO/TC 229 - Nanotechnologies
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 18-Sep-2026
• Completion Date: 18-Sep-2026

• Consolidates: ISO 12231-1:2020 - Photography — Electronic still picture imaging terminology — Part 1: Supplemental vocabulary
• Effective Date: 10-Dec-2022
• Revises: ISO/TS 80004-12:2016 - Nanotechnologies — Vocabulary — Part 12: Quantum phenomena in nanotechnology
• Effective Date: 26-Nov-2022

Overview

ISO/DTS 80004-12:2026, Nanotechnologies - Vocabulary - Part 12: Quantum phenomena in nanotechnology defines a comprehensive vocabulary for quantum phenomena as they relate to nanotechnology. Developed by ISO/TC 229 and its partners, this standard provides essential terms and definitions, facilitating communication among academia, industry, and other stakeholders involved in nanotechnology and quantum technologies. While focused on the nanoscale, many terms are also applicable to larger scales and other fields, offering a shared language for interdisciplinary innovation.

The document supports harmonization of terminology by structuring its content from fundamental concepts to more specific quantum effects and their application to devices and materials in nanotechnology.

Key Topics

• Background Terms: Foundational concepts such as models, operators, simulators, algorithms, machine learning, and metrology, including the specialized area of nanometrology.
• Quantum Concepts and Effects:
  • Hilbert space: The mathematical foundation for quantum states.
  • Quantum operators and Hamiltonians: Describe how quantum systems evolve.
  • Quantum states, superposition, and entanglement: Central phenomena in quantum physics.
  • Quantum coherence, decoherence, and coherence time: Crucial for quantum device performance.
  • Quantum noise and quantum-limited systems: Understanding the intrinsic limits of measurement and technology.
• Quantum Phenomena with Practical Implications:
  • Plasmons and surface plasmon resonance
  • Ballistic and coherent transport in nanoscale devices
  • Notable effects like quantum Hall effect, giant magnetoresistance, tunnelling magnetoresistance, and spin-transfer torque
• Quantum Technologies and Materials: The standard connects terminology to practical materials (e.g., semiconductors, superconductors, topological insulators, cold atoms) and enables clear description of devices such as quantum dots, wires, and enabling systems for computing, sensing, and communication.

Applications

The vocabulary established in ISO/DTS 80004-12 is vital for:

• Research & Development: Enables scientists and engineers to communicate unambiguously when describing quantum effects in nanoscale systems, accelerating collaboration and discovery.
• Product Design & Manufacturing: Assists manufacturers in the precise specification of nano-enabled and quantum-enabled products, such as quantum computers, sensors, and communication devices.
• Quality Control & Metrology: Supports accurate measurement, characterization, and verification of quantum phenomena and nanomaterials, critical for advanced semiconductor fabrication, medical diagnostics, and precision engineering.
• Industry Standardization: Facilitates harmonized technical documentation and regulatory compliance across the nanotechnology and quantum technology industries.
• Education & Training: Offers educators and trainers a consistent reference for instructing students and professionals in cutting-edge quantum and nanotechnologies.

Common use cases include defining protocols for quantum key distribution, developing quantum metrology tools (e.g., atomic clocks, quantum sensors), and advancing quantum computing hardware based on terms like qubits, quantum states, and coherence.

Related Standards

ISO/DTS 80004-12 is part of the ISO 80004 series, which covers general nanotechnology vocabulary and its many sub-disciplines, including materials, interfaces, and devices. Key related standards include:

• ISO 80004-1: Core terms and definitions for general nanotechnology.
• ISO/TS 80004-2: Vocabulary relating to nano-objects.
• ISO/TS 80004-3: Carbon nano-objects and related terminology.
• ISO/IEC 4879: Quantum information technology vocabulary.
• ISO/IEC 22989: Artificial intelligence concepts and terminology (with quantum machine learning aspects).

Integration with IEC Electropedia and ISO Online Browsing Platform ensures global access to standardized terminology, promoting worldwide alignment in nanotechnology and quantum fields.

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Keywords: nanotechnology vocabulary, quantum phenomena, ISO DTS 80004-12, quantum effects, quantum devices, quantum technologies, nanomaterial standards, quantum metrology, nanoscience, standardization.

FINAL DRAFT
Technical
Specification
ISO/TC 229
Nanotechnologies — Vocabulary —
Secretariat: BSI
Part 12:
Voting begins on:
2026-09-18
Quantum phenomena in
nanotechnology
Voting terminates on:
2026-12-11
Nanotechnologies — Vocabulaire —
Partie 12: Phénomènes quantiques dans les nanotechnologies
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
This draft is submitted to a parallel vote in ISO and in IEC.
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
Technical
Specification
ISO/TC 229
Nanotechnologies — Vocabulary —
Secretariat: BSI
Part 12:
Voting begins on:
Quantum phenomena in
nanotechnology
Voting terminates on:
Nanotechnologies — Vocabulaire —
Partie 12: Phénomènes quantiques dans les nanotechnologies
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
This draft is submitted to a parallel vote in ISO and in IEC.
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Background terms .1
3.2 General quantum concepts and quantum effects .2
3.3 Phenomena resulting from quantum effects .7
3.4 Quantum technologies: materials, devices, and applications .10
3.4.1 General quantum technology terms .10
3.4.2 Material platforms .11
3.4.3 Nanoscale enabling devices and technologies .14
3.4.4 Qubit types .16
3.4.5 Quantum technology sectors .18
3.4.6 Enabling systems and integration technologies .27
Bibliography .30
Index .32

iii
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical activity.
ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations,
governmental and non-governmental, in liaison with ISO and IEC, also take part in the work.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of document should be noted. This document was drafted in accordance with the editorial rules of the ISO/
IEC Directives, Part 2 (see www.iso.org/directives or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not
received notice of (a) patent(s) which may be required to implement this document. However, implementers
are cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held
responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
In the IEC, see www.iec.ch/understanding-standards.
This document was prepared jointly by Technical Committee ISO/TC 229, Nanotechnologies, and Technical
Committee IEC/TC 113, Nanotechnology for electrotechnical products and systems, and in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 352, Nanotechnologies, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement). The
draft was circulated for voting to the national bodies of both ISO and IEC.
This second edition cancels and replaces the first edition (ISO/TS 80004-12:2016), which has been
technically revised.
The main changes are as follows:
— addition of information on general quantum concepts and effects (see 3.2), phenomena resulting from
quantum effects (see 3.3); and quantum technologies (see 3.4);
— revision of references (see Bibliography).
A list of all parts in the ISO 80004 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html and
www.iec.ch/national-committees.

iv
Introduction
The interplay between nanoscale materials and quantum phenomena is a foundational aspect of both
nanotechnology and quantum technologies. As materials are reduced to the nanometer scale, quantum
effects such as energy level quantization and tunnelling become increasingly significant due to spatial
confinement in one, two, or three dimensions. These effects give rise to novel, size-dependent properties
governed by the principles of quantum physics. While not limited to the nanoscale, their manifestation at this
scale is critical for identifying nano-enabled products and advancing both nano- and quantum technology
fields.
Table 1 summarizes the relationship between the three major domains of quantum technologies: computing
and simulation, communication, and sensing and metrology, together with their associated devices and
enabling materials. Representative examples include qubit systems, quantum sensors, and single-photon
sources, which rely on materials such as superconductors, semiconductors, topological systems, cold atoms,
and Bose–Einstein condensates. Nanotechnology provides the methods to fabricate, control, and integrate
these materials and devices, thereby accelerating both fundamental research and technological applications.
Table 1 — Relationship between quantum technologies, devices and platforms, and enabling
materials
Quantum technologies Devices and platforms Enabling materials
Quantum computing Qubit platforms; Quantum-confined struc- Superconductors; Semiconductors; Topo-
and simulation tures; Quantum tunnelling devices; Quantum logical materials; Ferroelectric materials;
exchange structures Bose–Einstein condensates
Quantum communica- Single-photon sources and detectors; Quantum Nonlinear optical crystals; Defect-engi-
tion repeaters; QKD devices; Satellite links; Photonic neered materials; Plasmonic & photonic
and plasmonic circuits materials
Quantum sensing and Quantum sensors; NV-centre-based sensors; Cold atoms; Rydberg atoms; Defect-en-
metrology Atomic clocks; Quantum inertial sensors; Quan- gineered materials; Bose–Einstein con-
tum-enhanced imaging densates; Exciton–polaritons; Nonlinear
optical crystals
This document supports the harmonization of quantum-related terms within the broader nanotechnology
framework to promote clear and consistent communication among stakeholders in industry, academia,
government, and non-profit sectors.
The document is structured to progress from background terminology to general quantum concepts,
phenomena resulting from quantum effects, and terminology related to quantum technologies, including
materials, nanoscale enabling devices and technologies, qubit types, application sectors, and enabling
systems and integration technologies. Together, these terms provide a common vocabulary for concepts at
the intersection of quantum and nanoscale domains.

v
FINAL DRAFT Technical Specification ISO/DTS 80004-12:2026(en)
Nanotechnologies — Vocabulary —
Part 12:
Quantum phenomena in nanotechnology
1 Scope
This document defines terms related to quantum phenomena relevant to nanotechnologies.
This document is applicable to terminology used in describing quantum phenomena, quantum effects,
and quantum-enabled materials, devices, systems, and applications within the broader nanotechnology
framework.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Background terms
3.1.1
model
physical, mathematical, or otherwise appropriate representation of a system, entity, phenomenon, process,
or data
[SOURCE: ISO/IEC 4879:2024, 3.1.1]
3.1.2
operator
mathematical entity that transforms the elements of an input space to the elements of an output space
Note 1 to entry: In quantum physics (3.2.4), simple operators can be mathematically represented by a matrix that acts
via matrix multiplication on vectors in a Hilbert space (3.2.1)
[SOURCE: ISO/IEC 4879:2024, 3.2.2]
3.1.3
simulator
device, computer program, or system that behaves or operates like a given system when provided a set of
controlled inputs
[SOURCE: ISO/IEC/IEEE 24765:2017, 3.3750]

3.1.4
algorithm
process for computation, defined by a set of rules, that will yield a corresponding output
[SOURCE: ISO/IEC 4879:2024, 3.1.9]
3.1.5
machine learning
process of optimizing model (3.1.1) parameters through computational techniques, such that the model's
behaviour reflects the data or experience
Note 1 to entry: Machine learning encompasses a range of techniques, including supervised, unsupervised, and
reinforcement learning. In the context of quantum machine learning (3.4.5.1.21), such techniques are extended or
adapted using quantum algorithms (3.4.5.1.1), which offer computational advantages for tasks such as model training,
inference, and data encoding.
[SOURCE: ISO/IEC 22989:2022, 3.3.5, modified – Note 1 to entry added]
3.1.6
metrology
science of measurement and its application
Note 1 to entry: Metrology includes all theoretical and practical aspects of measurement, whatever the measurement
uncertainty and field of application.
Note 2 to entry: Metrology encompasses specialized fields such as nanometrology (3.1.7), addressing measurement
at the nanoscale, and quantum metrology (3.4.5.3.9), which uses quantum phenomena to improve measurement
precision, for example, in atomic clocks, interferometers, and dedicated quantum sensors (3.4.5.3.2).
[SOURCE: ISO Guide 99:2007, 2.2, modified – Note 2 to entry added to clarify applicability to nanotechnology
and quantum metrology]
3.1.7
nanometrology
science of measurement and its application at the nanoscale
Note 1 to entry: Nanometrology includes all theoretical and practical aspects of measurement where at least one
relevant dimension or uncertainty lies in the nanometer range (typically below 100  nm).
Note 2 to entry: Nanometrology supports measurements in nanotechnology and related fields, including semiconductor
fabrication, advanced materials, and quantum technologies (3.4.1.1).
3.2 General quantum concepts and quantum effects
3.2.1
Hilbert space
vector space equipped with an inner product operation, which allows distances, angles, and vector norms to
be defined
Note 1 to entry: In quantum physics (3.2.4), a Hilbert space is used to represent the possible pure states of a quantum
system (3.2.7).
Note 2 to entry: Hilbert space is defined mathematically as a complete inner product space and is applied beyond
quantum theory (e.g. to wave equations, signal processing, and functional analysis).
[SOURCE: ISO/IEC 4879:2024, 3.2.1, modified – Notes 1 and 2 to entry replaced]
3.2.2
quantum operator
operator (3.1.2) that acts on quantum states (3.2.14) in Hilbert space (3.2.1)
Note 1 to entry: Mathematically, a quantum operator is a linear operator (homomorphism) on a Hilbert space, and in
quantum theory is commonly associated with observables or time evolution of states.

[SOURCE: ISO/IEC 4879:2024, 3.2.11, modified – Note 1 to entry replaced]
3.2.3
Hamiltonian
quantum operator (3.2.2) that determines the coherent evolution of a quantum system
(3.2.7)
Note 1 to entry: In quantum mechanics, the Hamiltonian is the operator associated with the total energy observable of
a system; for a given quantum state, the expectation value of the Hamiltonian yields the mean energy.
[SOURCE: ISO/IEC 4879:2024, 3.2.12, Note 1 to entry replaced]
3.2.4
quantum physics
branch of physics comprising fundamental theories that explain the behaviour of matter and energy using
principles such as quantum superposition (3.2.17), quantization (3.2.13), and quantum entanglement (3.2.22),
and that formulate physical systems mathematically using Hilbert spaces (3.2.1) and linear operators
Note 1 to entry: Quantum physics provides a predictive framework for physical phenomena at all scales; classical
physics emerges as an approximation to quantum physics in appropriate limits.
Note 2 to entry: Quantum mechanics is one of the theoretical frameworks within quantum physics, together with
quantum field theory and many-body quantum theory.
Note 3 to entry: Quantum physics provides the foundation for quantum technologies, including quantum computing
(3.4.5.1.6), quantum communication (3.4.5.2.1), and quantum sensing and metrology (3.4.5.3).
3.2.5
quantum,adjective
making use of or arising from the laws of quantum physics (3.2.4) in an essential way
[SOURCE: ISO/IEC 4879:2024, 3.2.4]
3.2.6
quantum,noun
discrete, finite, indivisible, and measurable unit of a physical property such as energy
Note 1 to entry: The plural form of quantum is quanta.
[SOURCE: ISO/IEC 4879:2024, 3.2.5, modified – Note 1 to entry added]
3.2.7
quantum system
system whose properties are determined by the laws of quantum physics (3.2.4), and cannot be completely
described by just the laws of classical physics
[SOURCE: ISO/IEC 4879:2024, 3.2.6]
3.2.8
quantum phenomena
quantum effects
intrinsic properties and observable behaviours of physical systems that are fundamentally governed by the
principles of quantum physics (3.2.4)
Note 1 to entry: Examples include intrinsic properties, such as quantization (3.2.13) of energy levels and spin, and
observable behaviours, such as quantum superposition (3.2.17), entanglement (3.2.22), and tunnelling (3.2.25).
Note 2 to entry: Quantum effects can be harnessed at the nanoscale, but nanoscale and quantum phenomena are not
synonymous: some nanoscale phenomena are classical, and some quantum phenomena occur beyond the nanoscale.

3.2.9
quantum noise
fundamental fluctuations in measurable quantities of a quantum system (3.2.7) that arise from the
complementarity of quantum observables
Note 1 to entry: Quantum noise appears in different forms, such as shot noise (fluctuations from the discrete nature of
photons or electrons) and quantum back-action (fluctuations introduced by the act of measurement). Quantum noise
sets intrinsic limits on the precision of measurements and operations and defines the standard quantum limit for
precision. It can be redistributed in certain observables, for example, using squeezed states, in which uncertainty is
reduced in one variable at the expense of its conjugate.
Note 2 to entry: Quantum noise is a key factor in the operation and accuracy of quantum technologies (3.4.1.1).
It limits the sensitivity of quantum devices and must be managed in applications of quantummetrology (3.4.5.3.9),
quantumsensing (3.4.5.3.1), and other precision measurement methods.
3.2.10
quantum-limited,adjective
describing a system, process, or device whose performance is fundamentally constrained by the principles
of quantum physics (3.2.4), quantum noise (3.2.9), or limits imposed by quantum measurements (3.2.24)
Note 1 to entry: “Quantum-limited” is often used in reference to sensors, amplifiers, or measurement schemes
operating at or near the fundamental quantum noise limit.
Note 2 to entry: The designation “quantum-limited” is distinct from quantum (3.2.6), which refers to systems that
rely on quantum phenomena (3.2.8), and quantum-enhanced (3.2.11), which describes otherwise classical systems
that incorporate quantum resources to improve performance. A quantum-limited device may be quantum, quantum-
enhanced, or even classical, but its performance is ultimately bounded by quantum limits.
3.2.11
quantum-enhanced,adjective
describing a classical or semiclassical system, process, or device that leverages specific quantum phenomena
(3.2.8) to improve performance beyond what is achievable through purely classical means
Note 1 to entry: Quantum-enhanced refers to systems or technologies that incorporate quantum resources to improve
sensitivity, precision, security, or computational efficiency. Examples include quantum-enhanced sensing, metrology,
and magnetometry.
Note 2 to entry: Quantum-enhanced is distinct from systems where quantum phenomena (3.2.8) are intrinsic to the
operation, such as spectroscopy based on discrete atomic spectra arising from quantization (3.2.13) or quantum
sensing (3.4.5.3.1). In contrast, quantum-enhanced approaches add specific quantum resources to otherwise classical
or semiclassical systems to improve their performance.
3.2.12
de Broglie wavelength
wavelength associated with the momentum of a particle according to its wave-like properties
Note 1 to entry: The de Broglie wavelength is given by λ = h/p, where h is Planck’s constant and p is the magnitude of
the particle’s momentum vector.
Note 2 to entry: The de Broglie wavelength is relevant when particle dimensions approach nanoscale regimes,
influencing the onset of quantum confinement (3.2.26) effects.
3.2.13
quantization
property by which physical quantities can take only specific, discrete values rather than a continuum
Note 1 to entry: Examples of quantized physical properties include elementary electric charge and energy levels in
atoms, where electrons can only occupy specific energy levels.

3.2.14
quantum state
description of the state of a quantum system (3.2.7), defining the probability distribution of possible
outcomes of any measurement upon it
[SOURCE: ISO/IEC 4879:2024, 3.2.7, modified – Notes 1 and 2 to entry removed]
3.2.15
basis states
members of a set of quantum states (3.2.14) which span the Hilbert space (3.2.1) of a quantum system (3.2.7)
Note 1 to entry: Any quantum state in the Hilbert space can be written as a linear combination, or quantum
superposition (3.2.17), of basis states.
Note 2 to entry: A set of basis states is often chosen to be complete and orthonormal. That is, the set spans the entire
Hilbert space, and individual elements are orthogonal and normalized to length 1.
[SOURCE: ISO/IEC 4879:2024, 3.2.9]
3.2.16
wave function
wavefunction
mathematical function that describes the state of a quantum system (3.2.7)
Note 1 to entry: The state of a quantum system is also referred to as a quantum state (3.2.14).
Note 2 to entry: The wave function can be a function of momentum, time, position, spin, or any other relevant quantum
observable.
3.2.17
quantum superposition
complex linear combination of two or more different quantum states (3.2.14)
[SOURCE: ISO/IEC 4879:2024, 3.2.8]
3.2.18
quantum coherence
existence or extent of unambiguous phase relationships between possible states of a quantum system (3.2.7)
Note 1 to entry: Quantum coherence in a quantum system is often defined between populations of different basis states
(3.2.15) in an individual quantum state (3.2.14) of that quantum system.
[SOURCE: ISO/IEC 4879:2024, 3.2.18]
3.2.19
decoherence
quantum decoherence
loss or degradation of quantum coherence (3.2.18)
Note 1 to entry: Decoherence requires interaction between a quantum system (3.2.7) and environmental degrees of
freedom.
[SOURCE: ISO/IEC 4879:2024, 3.2.19]
3.2.20
coherence time
quantum coherence time
characteristic time scale for decoherence (3.2.19)
Note 1 to entry: Quantum coherence time is a key parameter in the performance of quantum sensors (3.4.5.3.2),
particularly in solid-state systems and nanoscale materials, such as NV centres in diamond (3.4.2.7), superconducting
quantum interference (3.2.27) devices, and other quantum-enabled platforms.
[SOURCE: ISO/IEC 4879:2024, 3.2.20 – modified; Note 1 to entry replaced]

3.2.21
quantum phase coherence
specific type of quantum coherence (3.2.18) with the preservation of phase in the spatial evolution of a
wavefunction (3.2.16), such as when particles move through a material or device
Note 1 to entry: The distance over which phase coherence is preserved is called the phase coherence length.
3.2.22
quantum entanglement
property of a quantum state (3.2.14) within a joint quantum system (3.2.7), consisting of at least two
subsystems, for which the quantum state cannot be described in terms of independent characteristics of its
individual constituents
Note 1 to entry: The properties of subsystems, e.g., of two photons correlated non-locally in such a way that the state
of one photon instantaneously influences the state of another, regardless of distance.
[SOURCE: ISO/IEC 4879:2024, 3.2.10, modified – Note 1 to entry added]
3.2.23
quantum entanglement swapping
process by which quantum entanglement (3.2.22) is generated between two previously unentangled quantum
systems (3.2.7) by performing a joint quantum measurement (3.2.24) on their respective entangled partners
Note 1 to entry: Entanglement swapping enables two particles to become entangled without direct interaction, and is
a fundamental protocol used in quantum repeaters (3.4.5.2.8) and quantum networks (3.4.5.2.9).
3.2.24
quantum measurement
process that yields a physical property of a quantum state (3.2.14)
Note 1 to entry: In practice, a quantum measurement yields a numerical value corresponding to an observable,
obtained through the interaction of the quantum system (3.2.7) with a measurement apparatus. Unlike classical
measurement, which reveals a pre-existing value, quantum measurement typically alters the system and projects it
into a definite outcome.
Note 2 to entry: For example, quantum measurements are used for qubit (3.2.28) readout in quantum computing
(3.4.5.1.6), for ultra-sensitive detection of biomolecules in biosensing, for precise determination of gravitational fields
in navigation, and for characterizing nanoscale quantum behaviour in systems such as quantum dots (3.4.2.3) and
quantum wires (3.4.2.4).
[SOURCE: ISO/IEC 4879:2024, 3.2.16, modified – Definition: “outputs” replaced with “yields”; Note 1 and
Note 2 to entry replaced]
3.2.25
quantum tunnelling
tunnelling
phenomenon in which a quantum particle has a finite probability of passing through a potential barrier that
it can not overcome according to classical physics
Note 1 to entry: Quantum tunnelling arises from the wave-like nature of particles described by quantum physics
(3.2.4), which allows a nonzero probability of finding the particle on the other side of an energy barrier even when its
classical kinetic energy is below the barrier height.
Note 2 to entry: Quantum tunnelling plays a critical role in nanoscale electronic devices such as tunnel diodes and
single-electron transistors (3.4.3.2, Note 1), where electron transport occurs through a thin insulating barrier. Beyond
nanoscale electronics, quantum tunnelling underlies physical processes such as alpha decay in nuclei, field emission of
electrons from surfaces, and imaging with scanning tunnelling microscopy (STM).

3.2.26
quantum confinement
phenomenon in which the electronic or optical properties of particles are altered when confined to
dimensions comparable to their de Broglie wavelength (3.2.12)
Note 1 to entry: Quantum confinement leads to discrete energy levels and size-dependent behaviour not observed in
bulk materials.
Note 2 to entry: Quantum confinement becomes significant in systems such as semiconductor quantum wells (3.4.2.5),
quantum wires (3.4.2.4), and quantum dots (3.4.2.3), where the extent of confinement determines the energy structure
and material properties.
3.2.27
quantum interference
phenomenon in which the probability of a quantum outcome is affected by the superposition of multiple
possible paths or states, resulting in constructive or destructive interference patterns arising from the
wave-like nature of quantum systems (3.2.7)
3.2.28
qubit
quantum bit
quantum system (3.2.7) with two basis states (3.2.15)
Note 1 to entry: Qubit stands for quantum (3.2.6) bit.
Note 2 to entry: Qubit is the smallest unit of quantum information (3.2.30).
Note 3 to entry: The Hilbert space (3.2.1) of a qubit is the space spanned by its two basis states. The quantum state
(3.2.14) of a qubit can therefore be any quantum superposition (3.2.17) of these states. A qubit is therefore the quantum
analogue of a classical bit, which can only take the values 0 or 1.
[SOURCE: ISO/IEC 4879:2024, 3.3.3, modified – In Note 3, the last sentence is added; Notes 4-6 to entry
omitted]
3.2.29
qudit
quantum dit
quantum system (3.2.7) with nbasis states (3.2.15) where n is an integer greater than or equal two
Note 1 to entry: Qudit stands for quantum (3.2.6) dit or quantum n-level system.
Note 2 to entry: Qudit is an n-fold unit of quantum information (3.2.30).
Note 3 to entry: Qubit (3.2.28) is a special case of qudit with n equal to 2.
[SOURCE: ISO/IEC 4879:2024, 3.3.4, modified – Notes 3, 4, 6, 7 to entry omitted]
3.2.30
quantum information
information contained or encoded in a quantum state (3.2.14).
Note 1 to entry: Quantum information may be transformed via quantum (3.2.6) operations and processes.
[SOURCE: ISO/IEC 4879:2024, 3.3.1]
3.3 Phenomena resulting from quantum effects
3.3.1
plasmon
quantum (3.2.6) of collective electron oscillations in a metal or a semiconductor
Note 1 to entry: In condensed-matter physics, a plasmon is commonly described as a quasiparticle associated with a
collective oscillation of the electron gas.

[SOURCE: ISO 21466:2019, 3.37, modified – Notes 1 to entry added]
3.3.2
surface plasmon
plasmon (3.3.1) corresponding to a collective oscillation of free electrons bound to and propagating along
the surface of a metal, stimulated by electromagnetic waves
Note 1 to entry: Surface plasmons are typically confined to the interface between the metal and a dielectric and
propagate along that surface.
Note 2 to entry: Surface plasmons are central to plasmonics (3.4.3.12), nanophotonics (3.4.3.9), and sensing technologies,
enabling applications such as enhanced spectroscopies, single-photon sources, and quantum sensing (3.4.5.3.1).
3.3.3
surface plasmon resonance
resonant excitation of surface plasmons (3.3.2) by an external electromagnetic field
Note 1 to entry: Surface plasmon resonance is widely used in biosensing and optical detection due to its high sensitivity
to changes in the local refractive index near the metal surface.
3.3.4
magnon
quantum (3.2.6) of a spin wave in a magnetically ordered material
Note 1 to entry: In condensed-matter physics, a magnon is commonly described as a quasiparticle associated with a
collective excitation of electron spins.
3.3.5
ballistic transport
regime of carrier motion in which particles propagate through the system without scattering, typically
occurring when the characteristic dimensions of the system are smaller than the carriers’ mean free path or
momentum relaxation length
Note 1 to entry: The ballistic transport regime is significant in nanoscale systems, such as quantum wires (3.4.2.4),
where quantum effects dominate over classical scattering processes.
3.3.6
coherent transport
regime of particle or wave propagation in which quantum phase coherence (3.2.21) is preserved throughout
the transport process, typically occurring when the dimensions of the system are smaller than the phase
coherence length
Note 1 to entry: Coherent transport enables interference effects and is central to phenomena such as conductance
quantization (3.2.13) in mesoscopic and nanoscale systems.
3.3.7
Coulomb blockade
suppression of electron tunnelling into a small conductive region, such as a quantum dot (3.4.2.3), through a
tunnel junction, caused by Coulomb repulsion and the Pauli exclusion principle
Note 1 to entry: Coulomb blockade arises from charge quantization (3.2.13) and is fundamental to the operation of
single-electron electronics (3.4.3.2), where it enables control of electrical transport one electron at a time.
3.3.8
quantum Hall effect
QHE
quantization (3.2.13) of Hall conductance in two-dimensional electron systems under low temperatures and
strong magnetic fields, where the conductance takes discrete values that are integer or fractional multiples
of the conductance quantum (3.2.5)
Note 1 to entry: When the quantized values correspond to integers, the phenomenon is known as the “integer quantum
Hall effect”; when they are rational fractions, it is referred to as the “fractional quantum Hall effect”, arising from
electron–electron interactions and correlated quantum states (3.2.14).

Note 2 to entry: Related variants of the QHE also exist without an externally applied magnetic field. For example, the
anomalous quantum Hall effect (AQHE) in magnetic topological insulators (3.4.2.10) arises from intrinsic magnetic
order and strong spin–orbit coupling.
Note 3 to entry: Spin Hall effect (3.3.14) is a distinct phenomenon that also produces a transverse response but does
not require an external magnetic field or quantization (3.2.13).
3.3.9
giant magnetoresistance
GMR
quantum effect (3.2.8) in which the electrical resistance of a material changes significantly in response to an
applied magnetic field due to spin-dependent electron scattering
Note 1 to entry: GMR typically occurs in multilayer heterostructures composed of alternating ferromagnetic and
nonmagnetic conductive layers, where the relative alignment of magnetic moments influences resistance. It is widely
used in magnetic read heads, sensors, and spintronic devices.
Note 2 to entry: GMR is distinct from tunnelling magnetoresistance (3.3.10), which involves spin-dependent tunnelling
through an insulating barrier, and colossal magnetoresistance (3.3.11), which occurs in bulk correlated materials.
3.3.10
tunnelling magnetoresistance
TMR
quantum effect (3.2.8) in which the electrical resistance of a junction composed of two ferromagnetic layers
separated by a thin insulating barrier depends on the relative alignment of the magnetic moments, due to
spin-dependent quantum tunnelling (3.2.25) of electrons
Note 1 to entry: TMR is typically observed in magnetic tunnel junctions (xx), where resistance is lower when the
magnetizations of the two ferromagnetic layers are parallel and higher when they are antiparallel. It is exploited in
spintronics (3.4.3.7) applications such as magnetic random-access memory (MRAM), sensors, and hard disk drive read
heads.
Note 2 to entry: TMR is distinct from giant magnetoresistance (3.3.9), which arises from spin-dependent scattering in
conductive multilayers, and colossal magnetoresistance (3.3.11), which occurs in bulk correlated materials.
3.3.11
colossal magnetoresistance
CMR
quantum effect (3.2.8) observed in certain bulk materials, where strong electron correlations and coupling
between charge, spin, orbital, and lattice degrees of freedom lead to extremely large changes in electrical
resistance in response to a magnetic field
Note 1 to entry: CMR is typically observed in manganese oxides and related strongly correlated electron systems. It
can produce resistance changes several orders of magnitude greater than those observed in giant magnetoresistance
(3.3.9) and is studied for applications in magnetic sensors and spintronic devices.
Note 2 to entry: Unlike giant magnetoresistance and tunnelling magnetoresistance (3.3.10), which arise in engineered
multilayer junctions, CMR is an intrinsic property of bulk materials.
3.3.12
spin-transfer torque
STT
quantum effect (3.2.8), in which a spin-polarized electric current transfers angular momentum to the
magnetization of a ferromagnetic material, exerting a torque that can reorient the magnetization
Note 1 to entry: Spin-transfer torque is exploited in spintronic devices such as spin-transfer torque magnetic random-
access memory (STT-MRAM).
3.3.13
spin-orbit torque
SOT
quantum effect (3.2.8), in which spin–orbit coupling converts an electric current into a spin current that
exerts a torque on the magnetization of an adjacent ferromagnetic layer
Note 1 to entry: Spin-orbit torque typically arises from the spin Hall effect (3.3.14) or from interfacial mechanisms
such as the Rashba–Edelstein effect. It enables efficient magnetization switching in spintronic devices such as spin-
orbit torque magnetic random-access memory (SOT-MRAM).
3.3.14
spin Hall effect
quantum effect (3.2.8), in which an electric current in a material with strong spin–orbit coupling generates a
transverse spin current, leading to the accumulation of spins of opposite orientation on opposite sides of the
material
Note 1 to entry: Spin Hall effect does not require an external magnetic field and is distinct from the quantum Hall effect
(3.3.8).
Note 2 to entry: Spin Hall effect provides a mechanism for spin-orbit torque (3.3.13) and for generating spin currents in
spintronic devices.
3.4 Quantum technologies: materials, devices, and applications
3.4.1 General quantum technology terms
3.4.1.1
quantum technologies
broad class of technologies that utilize quantum phenomena (3.2.8) to achieve functionality or performance
beyond what is possible with classical physics, including but not limited to quantum information technologies
(3.4.1.2)
Note 1 to entry: In addition to quantum information technologies, quantum technologies include quantum-enabled
devices that do not explicitly process information, such as quantum-limited sensors (3.4.5.3.3) and detectors (3.4.5.3.4),
as well as quantum-enhanced (3.2.11) classical devices like superconducting quantum interference (3.2.27) devices
(SQUIDs) and atomic clocks. The term also encompasses materials and systems whose functionality depends on
quantum behaviour, even if they are not framed within an information-processing context.
3.4.1.2
quantum information technologies
QIT
technologies that apply principles of quantum information (3.2.30) science, such as superposition (3.2.17),
entanglement (3.2.22), and quantum measurement (3.2.24), to process, transmit, or extract information in
ways that surpass classical capabilities
Note 1 to entry: Quantum information technologies represent a distinct subset of quantum technologies (3.4.1.1),
focused on high-performance computing and simulation, secure communication, and advanced sensing. Examples
include quantum computers (3.4.5.1.5) and simulators (3.4.5.1.17) for computation and modelling, quantum key
distribution (QKD) systems (3.4.5.2.6) for secure communication, and quantum sensors (3.4.5.3.2) for precision
measurements.
Note 2 to entry: These technologies can be realized on a variety of physical platforms, including superconducting qubits
(3.4.4.4), trapped-ion qubits (3.4.4.5), neutral-atom qubits (3.4.4.6), photonic qubits (3.4.4.7), spin qubits (3.4.4.3), and
defect-based qubits such as NV centres in diamond (3.4.2.7).
3.4.1.3
quantum information processing
process, algorithm (3.1.4), or computation that stores and processes quantum information (3.2.30) using, in
an essential way, properties such as quantum superposition (3.2.17) and quantum entanglement (3.2.22)
Note 1 to entry: Examples of common quantum processes where fidelities are reported include quantum gates
(3.4.5.1.2) and quantum measurements (3.2.24).

[SOURCE: ISO/IEC 4879:2024, 3.4.1]
3.4.1.4
quantum processor
tangible device that performs quantum information processing (3.4.1.3)
[SOURCE: ISO/IEC 4879:2024, 3.4.8]
3.4.2 Material platforms
3.4.2.1
quantum materials
material systems whose properties and behaviour are fundamentally governed or significantly influenced
by quantum effects (3.2.8), such as quantum entanglement (3.2.22) and quantum coherence (3.2.18), and that
cannot be fully explained by classical physics
Note 1 to entry: Quantum materials are often characterized by strong electronic correlations or nontrivial topological
band structures, giving rise to emergent phenomena such as superconductivity, the surface conduction behaviour of
topological insulators (3.4.2.8), and quantum spin liquid (3.4.2.11) states.
Note 2 to entry: Examples include superconductors, graphene, transition metal dichalcogenides, and Mott insulators,
each demonstrating quantum phenomena (3.2.8) such as topological surface states, electronic band inversion, or
strong electron–electron interactions.
3.4.2.2
materials for quantum applications
materials used in the development, implementation, or operation of quantum technologies (3.4.1.1), including
both quantum materials (3.4.2.1), whose behaviour is governed by quantum effects (3.2.8), and classical or
engineered materials that enable or support quantum functionality
Note 1 to entry: Examples include ultra-pure dielectrics, low-loss optical coatings, and isotopically enriched substrates
such as Si, which are used in quantum devices to minimize decoherence (3.2.19) and enhance control.
3.4.2.3
quantum dot
nanoparticle or nanostructure that exhibits quantum confinement (3.2.26) in all three spatial dimensions
Note 1 to entry: Examples include nanocrystalline CdSe suspension for display technology and biolabeling, self-
assembled InAs quantum dots for single-photon emitters (3.4.3.10) in quantum communication (3.4.5.2.1), and
nanolithographically fabricated Si quantum dots for spintronics (3.4.3.7)
3.4.2.4
quantum wire
quasi-one-dimensional nanostructure that exhibits quantum confinement (3.2.26) in two spatial dimensions,
allowing charge carriers, such as electrons or holes, to move freely in the third dimension
Note 1 to entry: Examples include carbon nanotube field-effect transistors for nanoelectronics (3.4.3.1) and quantum
interference (3.2.27) devices; Bi Se topological insulator (3.4.2.8) nanowires for quantum sensors (3.4.5.3.2) and
2 3
quantum computing (3.4.5.1.6).
3.4.2.5
quantum well
planar nanostructure that exhibits quantum confinement (3.2.26) in one spatial dimension, allowing charge
carriers, such as electrons or holes, to move freely in the other two dimensions
Note 1 to entry: Examples include GaAs/AlGaAs quantum wells for quantum well lasers in optoelectronics, InGaN/
GaN quantum wells for light-emitting diodes, and GaN/AlGaN quantum wells for high-elec
...

ISO/TC 229/JWG 1
Secretariat: BSI
Date: 2026-09-04
Nanotechnologies — Vocabulary —
Part 12:
Quantum phenomena in nanotechnology
Nanotechnologies — Vocabulaire —
Partie 12: Phénomènes quantiques dans les nanotechnologies

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© ISO/IEC 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, GenevaEmail
Phone: + 41 22 749 01 11
E-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
Contents
Page
Foreword . v
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Background terms . 1
3.2 General quantum concepts and quantum effects . 3
3.3 Phenomena resulting from quantum effects . 10
3.4 Quantum technologies: materials, devices, and applications . 13
Bibliography . 41
Index 43
iv
Introduction . v
1 Scope . 1
2 Normative References . 1
3 Terms and Definitions . 1
Background terms . 1
General quantum concepts and quantum effects . 2
Phenomena resulting from quantum effects . 8
Quantum technologies: materials, devices, and applications ……………………………………… 10
General quantum technology terms ………………………………………………………….
Material platforms …………………….………………………………………………………………. 11
Nanoscale enabling devices and technologies  ………………………………………………. 14
Qubit types .……………………………………………………….………………………………………. 17
Quantum technology sectors ………………………………………………………….……………. 19

Enabling systems and integration technologies………………………………………………. .  29
4 Bibliography……………………………………………………………………………………………………………………….
5 Index………………………………………………………………………………………………………………………………….  34

iv
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members
of ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, also take part in the work in liaison with ISO and IEC, also take part in the work.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
documentsdocument should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directiveswww.iso.org/directives or
www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the use of
(a) patent(s). ISO and IEC take no position concerning the evidence, validity, or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not received
notice of (a) patent(s) thatwhich may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent database
available at www.iso.org/patents and https://patents.iec.chwww.iso.org/patents and https://patents.iec.ch.
ISO and IEC shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO- specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html. In the IEC, see www.iec.ch/understanding-
standards.
This document was prepared jointly by Technical Committee ISO/TC 229, Nanotechnologies, and Technical
Committee IEC/TC 113, Nanotechnology for electrotechnical products and systems, and in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 352, Nanotechnologies, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement). The draft
was circulated for voting to the national bodies of both ISO and IEC.
This second edition, which has been technically revised, cancels and replaces the first edition (ISO/TS 80004-
12:2016).), which has been technically revised.
The main changes are as follows:
— Creationaddition of sectionsinformation on Generalgeneral quantum concepts and effects (see
3.2subclause 3.2); Phenomena), phenomena resulting from quantum effects (see 3.3subclause 3.3);); and
Quantumquantum technologies: materials, devices and applications (see 3.4Subclause 3.4));
— Updating revision of references (see Bibliography (see clause 4) and cross references (throughout the
document)).
A list of all parts in the ISO 80004 series can be found on the ISO website. and IEC websites.

v
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html and www.iec.ch/national-
committees.
vi
Introduction
The interplay between nanoscale materials and quantum phenomena is a foundational aspect of both
nanotechnology and quantum technologies. As materials are reduced to the nanometer scale, quantum effects
such as energy level quantization and tunnelling become increasingly significant due to spatial confinement
in one, two, or three dimensions. These effects give rise to novel, size-dependent properties governed by the
principles of quantum physics. While not limited to the nanoscale, their manifestation at this scale is critical
for identifying nano-enabled products and advancing both nano- and quantum technology fields.
Table 1Table 1 summarizes the relationship between the three major domains of quantum technologies:
computing and simulation, communication, and sensing and metrology, together with their associated devices
and enabling materials. Representative examples include qubit systems, quantum sensors, and single-photon
sources, which rely on materials such as superconductors, semiconductors, topological systems, cold atoms,
and Bose–Einstein condensates. Nanotechnology provides the methods to fabricate, control, and integrate
these materials and devices, thereby accelerating both fundamental research and technological applications.

Table 1. Relationship between quantum technologies, devices & platforms, and enabling materials
Table 1 — Relationship between quantum technologies, devices and platforms, and enabling
materials
Quantum Devices and Platformsplatforms Enabling Materialsmaterials
Technologiestechn
ologies
Quantum computing Qubit platforms; Quantum-confined structures; Superconductors; Semiconductors;
and simulation Quantum tunnelling devices; Quantum Topological materials; Ferroelectric
exchange structures materials; Bose–Einstein condensates
Quantum Single-photon sources and detectors; Quantum Nonlinear optical crystals; Defect-
communication repeaters; QKD devices; Satellite links; engineered materials; Plasmonic &
Photonic and plasmonic circuits photonic materials
Quantum sensing and Quantum sensors; NV-centre-based sensors; Cold atoms; Rydberg atoms; Defect-
metrology Atomic clocks; Quantum inertial sensors; engineered materials; Bose–Einstein
Quantum-enhanced imaging condensates; Exciton–polaritons;
Nonlinear optical crystals
This document supports the harmonization of quantum-related terms within the broader nanotechnology
framework to promote clear and consistent communication among stakeholders in industry, academia,
government, and non-profit sectors.
The document is structured to progress from background terminology to general quantum concepts,
phenomena resulting from quantum effects, and terminology related to quantum technologies, including
materials, nanoscale enabling devices and technologies, qubit types, application sectors, and enabling systems
and integration technologies. Together, these terms provide a common vocabulary for concepts at the
intersection of quantum and nanoscale domains.

vii
Nanotechnologies — Vocabulary —
Part 12:
Quantum phenomena in nanotechnology
1 Scope
This document defines terms related to quantum phenomena relevant to nanotechnologies.
This document is applicable to terminology used in describing quantum phenomena, quantum effects, and
quantum-enabled materials, devices, systems, and applications within the broader nanotechnology
framework.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/

3.1 Background terms
3.1.1
model
physical, mathematical, or otherwise appropriate representation of a system, entity, phenomenon, process, or
data
[SOURCE: ISO/IEC 4879:2024, 3.1.1]
3.1.2
3.1.3
operator
mathematical entity that transforms the elements of an input space to the elements of an output space
Note 1 to entry: In quantum physics (3.2.4), simple operators can be mathematically represented by a matrix that acts
via matrix multiplication on vectors in a Hilbert space (3.2.1)
Field Code Changed
[SOURCE: ISO/IEC 4879:2024, 3.2.2]

3.1.43.1.3
3.1.5
simulator
device, computer program, or system that behaves or operates like a given system when provided a set of
controlled inputs
[SOURCE: ISO/IEC/IEEE 24765:2017, 3.3750]
3.1.63.1.4
3.1.7
algorithm
process for computation, defined by a set of rules, that will yield a corresponding output
[SOURCE: ISO/IEC 4879:2024, 3.1.9]
3.1.83.1.5
3.1.9
machine learning
process of optimizing model (3.1.1) parameters through computational techniques, such that the model's
behaviour reflects the data or experience
Note 1 to entry: Machine learning encompasses a range of techniques, including supervised, unsupervised, and
reinforcement learning. In the context of quantum machine learning (3.4.5.1.21), such techniques are extended or adapted
using quantum algorithms (3.4.5.1.1), which offer computational advantages for tasks such as model training, inference,
and data encoding.
[SOURCE: ISO/IEC 22989:2022, 3.3.5, modified – Note 1 to entry added]
3.1.103.1.6
metrology
science of measurement and its application
Note 1 to entry: Metrology includes all theoretical and practical aspects of measurement, whatever the measurement
uncertainty and field of application.
Note 2 to entry: Metrology encompasses specialized fields such as nanometrology (3.1.7), addressing measurement at
the nanoscale, and quantum metrology (3.4.5.3.9), which uses quantum phenomena to improve measurement precision,
for example, in atomic clocks, interferometers, and dedicated quantum sensors (3.4.5.3.2).

[SOURCE: ISO Guide 99:2007, 2.2, modified – Note 2 to entry added to clarify applicability to nanotechnology
and quantum metrology]
3.1.113.1.7
3.1.12
nanometrology
science of measurement and its application at the nanoscale

Note 1 to entry: Nanometrology includes all theoretical and practical aspects of measurement where at least one
relevant dimension or uncertainty lies in the nanometer range (typically below 100 nm100  nm).

Note 2 to entry: Nanometrology supports measurements in nanotechnology and related fields, including semiconductor
fabrication, advanced materials, and quantum technologies (3.4.1.1)).

3.2  General quantum concepts and quantum effects
3.2.1
Hilbert space
vector space equipped with an inner product operation, which allows distances, angles, and vector norms to
be defined
Note 1 to entry: In quantum physics (3.2.4), a Hilbert space is used to represent the possible pure states of a quantum
system (3.2.7(3.2.7).).
Note 2 to entry: Hilbert space is defined mathematically as a complete inner product space and is applied beyond
quantum theory (e.g. to wave equations, signal processing, and functional analysis).
[SOURCE: ISO/IEC 4879:2024, 3.2.1, modified – Notes 1 and 2 to entry replaced]
3.2.2
quantum operator
operator (3.1.2) that acts on quantum states (3.2.14) in Hilbert space (3.2.1)
Field Code Changed
Note 1 to entry: Mathematically, a quantum operator is a linear operator (homomorphism) on a Hilbert space, and in
quantum theory is commonly associated with observables or time evolution of states.
[SOURCE: ISO/IEC 4879:2024, 3.2.11, modified – Note 1 to entry replaced]
3.2.3
Hamiltonian
quantum operator (3.2.2) that determines the coherent evolution of a quantum system
(3.2.7)
Field Code Changed
Note 1 to entry: In quantum mechanics, the Hamiltonian is the operator associated with the total energy observable of
a system; for a given quantum state, the expectation value of the Hamiltonian yields the mean energy.
[SOURCE: ISO/IEC 4879:2024, 3.2.12, Note 1 to entry replaced]
3.2.4
quantum physics
branch of physics comprising fundamental theories that explain the behaviorbehaviour of matter and energy
using principles such as quantum superposition (3.2.17), quantization (3.2.13), and quantum entanglement
(3.2.22), and that formulate physical systems mathematically using Hilbert spaces (3.2.1) and linear operators
Note 1 to entry: Quantum physics provides a predictive framework for physical phenomena at all scales; classical
physics emerges as an approximation to quantum physics in appropriate limits.
Note 2 to entry: Quantum mechanics is one of the theoretical frameworks within quantum physics, together with
quantum field theory and many-body quantum theory.
Note 3 to entry: Quantum physics provides the foundation for quantum technologies, including quantum computing
(3.4.5.1.6), quantum communication (3.4.5.2.1), and quantum sensing and metrology (3.4.5.3).
Field Code Changed
3.2.5
quantum, adjective
making use of or arising from the laws of quantum physics (3.2.4) in an essential way
[SOURCE: ISO/IEC 4879:2024, 3.2.4]
3.2.6
3.2.7
quantum, noun
discrete, finite, indivisible, and measurable unit of a physical property such as energy
Note 1 to entry: The plural form of quantum is quanta.
[SOURCE: ISO/IEC 4879:2024, 3.2.5, modified – Note 1 to entry added]
3.2.83.2.7
3.2.9
quantum system
system whose properties are determined by the laws of quantum physics (3.2.4), and cannot be completely
described by just the laws of classical physics
[SOURCE: ISO/IEC 4879:2024, 3.2.6]
3.2.103.2.8
3.2.11
quantum phenomena
quantum effects
intrinsic properties and observable behaviorsbehaviours of physical systems that are fundamentally governed
by the principles of quantum physics (3.2.4)

Note 1 to entry: Examples include intrinsic properties, such as quantization (3.2.13) of energy levels and spin, and
observable behaviorsbehaviours, such as quantum superposition (3.2.17), entanglement (3.2.22), and tunnelling (3.2.25).
Field Code Changed
Note 2 to entry: Quantum effects can be harnessed at the nanoscale, but nanoscale and quantum phenomena are not
synonymous: some nanoscale phenomena are classical, and some quantum phenomena occur beyond the nanoscale.

3.2.123.2.9
quantum noise
fundamental fluctuations in measurable quantities of a quantum system (3.2.7) that arise from the
complementarity of quantum observables

Note 1 to entry: Quantum noise appears in different forms, such as shot noise (fluctuations from the discrete nature of
photons or electrons) and quantum back-action (fluctuations introduced by the act of measurement). Quantum noise sets
intrinsic limits on the precision of measurements and operations and defines the standard quantum limit for precision.
It can be redistributed in certain observables, for example, using squeezed states, in which uncertainty is reduced in one
variable at the expense of its conjugate.

Note 2 to entry: Quantum noise is a key factor in the operation and accuracy of quantum technologies (3.4.1.1). It limits
the sensitivity of quantum devices and must be managed in applications of quantum metrologyquantum metrology
(3.4.5.3.9), quantum sensingquantum sensing (3.4.5.3.1), and other precision measurement methods.

3.2.133.2.10
quantum-limited, adjective
describing a system, process, or device whose performance is fundamentally constrained by the principles of
quantum physics (3.2.4), quantum noise (3.2.9), or limits imposed by quantum measurements (3.2.24)
Field Code Changed
Note 1 to entry: “Quantum-limited” is often used in reference to sensors, amplifiers, or measurement schemes operating
at or near the fundamental quantum noise limit.

Note 2 to entry: The designation “quantum-limited” is distinct from quantum (3.2.6(3.2.6),), which refers to systems
that rely on quantum phenomena (3.2.8), and quantum-enhanced (3.2.11), which describes otherwise classical systems
that incorporate quantum resources to improve performance. A quantum-limited device may be quantum, quantum-
enhanced, or even classical, but its performance is ultimately bounded by quantum limits.
3.2.143.2.11
quantum-enhanced, adjective
describing a classical or semiclassical system, process, or device that leverages specific quantum phenomena
(3.2.8) to improve performance beyond what is achievable through purely classical means
Field Code Changed
Note 1 to entry: Quantum-enhanced refers to systems or technologies that incorporate quantum resources to improve
sensitivity, precision, security, or computational efficiency. Examples include quantum-enhanced sensing, metrology, and
magnetometry.
Note 2 to entry: Quantum-enhanced is distinct from systems where quantum phenomena (3.2.8) are intrinsic to the
operation, such as spectroscopy based on discrete atomic spectra arising from quantization (3.2.13) or quantum sensing
(3.4.5.3.1). In contrast, quantum-enhanced approaches add specific quantum resources to otherwise classical or
semiclassical systems to improve their performance.
3.2.153.2.12
3.2.16
de Broglie wavelength
wavelength associated with the momentum of a particle according to its wave-like properties

Note 1 to entry: The de Broglie wavelength is given by λ = h/p, where h is Planck’s constant and p is the magnitude of
the particle’s momentum vector .

Note 2 to entry: The de Broglie wavelength is relevant when particle dimensions approach nanoscale regimes,
influencing the onset of quantum confinement (3.2.26) effects.
Field Code Changed
3.2.173.2.13
quantization
property by which physical quantities can take only specific, discrete values rather than a continuum

Note 1 to entry: Examples of quantized physical properties include elementary electric charge and energy levels in
atoms, where electrons can only occupy specific energy levels.

3.2.183.2.14
quantum state
description of the state of a quantum system (3.2.7), defining the probability distribution of possible outcomes
of any measurement upon it
[SOURCE: ISO/IEC 4879:2024, 3.2.7, modified – Notes 1 and 2 to entry removed]
3.2.193.2.15
3.2.20
basis states
members of a set of quantum states (3.2.14) which span the Hilbert space (3.2.1) of a quantum system (3.2.7)
Note 1 to entry: Any quantum state in the Hilbert space can be written as a linear combination, or quantum
superposition (3.2.17), of basis states.
Field Code Changed
Note 2 to entry: A set of basis states is often chosen to be complete and orthonormal. That is, the set spans the entire
Hilbert space, and individual elements are orthogonal and normalized to length 1.
[SOURCE: ISO/IEC 4879:2024, 3.2.9]
3.2.213.2.16
3.2.22
wave function
wavefunction
mathematical function that describes the state of a quantum system (3.2.7)

Note 1 to entry: The state of a quantum system is also referred to as a quantum state (3.2.14).

Note 2 to entry: The wave function can be a function of momentum, time, position, spin, or any other relevant quantum
observable.
3.2.233.2.17
quantum superposition
complex linear combination of two or more different quantum states (3.2.14)
[SOURCE: ISO/IEC 4879:2024, 3.2.8]
3.2.243.2.18
3.2.25
quantum coherence
existence or extent of unambiguous phase relationships between possible states of a quantum system (3.2.7)
Field Code Changed
Note 1 to entry: Quantum coherence in a quantum system is often defined between populations of different basis states
(3.2.15) in an individual quantum state (3.2.14) of that quantum system.
Field Code Changed
[SOURCE: ISO/IEC 4879:2024, 3.2.18]
3.2.263.2.19
3.2.27
decoherence
quantum decoherence
loss or degradation of quantum coherence (3.2.18)

Note 1 to entry: Decoherence requires interaction between a quantum system (3.2.7) and environmental degrees of
freedom.
[SOURCE: ISO/IEC 4879:2024, 3.2.19]
3.2.283.2.20
3.2.29
coherence time
quantum coherence time
characteristic time scale for decoherence (3.2.19)
Note 1 to entry: Quantum coherence time is a key parameter in the performance of quantum sensors (3.4.5.3.2),
particularly in solid-state systems and nanoscale materials, such as NV centres in diamond (3.4.2.7), superconducting
quantum interference (3.2.27) devices, and other quantum-enabled platforms.
Field Code Changed
[SOURCE: ISO/IEC 4879:2024, 3.2.20 – modified; Note 1 to entry replaced]
3.2.303.2.21
3.2.31
quantum phase coherence
specific type of quantum coherence (3.2.18) with the preservation of phase in the spatial evolution of a
wavefunction (3.2.16), such as when particles move through a material or device

Note 1 to entry: the The distance over which phase coherence is preserved is called the phase coherence length.

3.2.323.2.22
quantum entanglement
property of a quantum state (3.2.14) within a joint quantum system (3.2.7), consisting of at least two
subsystems, for which the quantum state cannot be described in terms of independent characteristics of its
individual constituents
Note 1 to entry: The properties of subsystems, e.g., of two photons correlated non-locally in such a way that the state
of one photon instantaneously influences the state of another, regardless of distance.
[SOURCE: ISO/IEC 4879:2024, 3.2.10, modified – Note 1 to entry added]

3.2.333.2.23
3.2.34
quantum entanglement swapping
process by which quantum entanglement (3.2.22) is generated between two previously unentangled quantum
systems (3.2.7) by performing a joint quantum measurement (3.2.24) on their respective entangled partners
Note 1 to entry: Entanglement swapping enables two particles to become entangled without direct interaction, and is
a fundamental protocol used in quantum repeaters (3.4.5.2.8) and quantum networks (3.4.5.2.9).

3.2.353.2.24
quantum measurement
process that yields a physical property of a quantum state (3.2.14)

Note 1 to entry: In practice, a quantum measurement yields a numerical value corresponding to an observable, obtained
through the interaction of the quantum system (3.2.7) with a measurement apparatus. Unlike classical measurement,
which reveals a pre-existing value, quantum measurement typically alters the system and projects it into a definite
outcome.
Note 2 to entry: For example, quantum measurements are used for qubit (3.2.28) readout in quantum computing
(3.4.5.1.6), for ultra-sensitive detection of biomolecules in biosensing, for precise determination of gravitational fields in
navigation, and for characterizing nanoscale quantum behaviorbehaviour in systems such as quantum dots (3.4.2.3) and
quantum wires (3.4.2.4(3.4.2.4).).
[SOURCE: ISO/IEC 4879:2024, 3.2.16, modified – Definition: “outputs” replaced with “yields”; Note 1 and Note
2 to entry replaced]
3.2.363.2.25
3.2.37
quantum tunnelling
tunnelling
phenomenon in which a quantum particle has a finite probability of passing through a potential barrier that it
couldcan not overcome according to classical physics
Note 1 to entry: Quantum tunnelling arises from the wave-like nature of particles described by quantum physics (3.2.4),
which allows a nonzero probability of finding the particle on the other side of an energy barrier even when its classical
kinetic energy is below the barrier height.
Note 2 to entry: Quantum tunnelling plays a critical role in nanoscale electronic devices such as tunnel diodes and single-
electron transistors (,(3.4.3.2, Note 1), where electron transport occurs through a thin insulating barrier. Beyond
nanoscale electronics, quantum tunnelling underlies physical processes such as alpha decay in nuclei, field emission of
electrons from surfaces, and imaging with scanning tunnelling microscopy (STM).
3.2.383.2.26
quantum confinement
phenomenon in which the electronic or optical properties of particles are altered when confined to
dimensions comparable to their de Broglie wavelength (3.2.12)
Field Code Changed
Note 1 to entry: Quantum confinement leads to discrete energy levels and size-dependent behaviorbehaviour not
observed in bulk materials.
Note 2 to entry: Quantum confinement becomes significant in systems such as semiconductor quantum wells (3.4.2.5),
quantum wires (3.4.2.4(3.4.2.4),), and quantum dots (3.4.2.3), where the extent of confinement determines the energy
structure and material properties.

3.2.393.2.27
quantum interference
phenomenon in which the probability of a quantum outcome is affected by the superposition of multiple
possible paths or states, resulting in constructive or destructive interference patterns arising from the wave-
like nature of quantum systems (3.2.7)
Field Code Changed
3.2.403.2.28
qubit
quantum bit
quantum system (3.2.7) with two basis states (3.2.15)

Note 1 to entry: Qubit stands for quantum (3.2.6(3.2.6)) bit.
Note 2 to entry: Qubit is the smallest unit of quantum information (3.2.30).
Field Code Changed
Note 3 to entry: The Hilbert space (3.2.1) of a qubit is the space spanned by its two basis states. The quantum state
(3.2.14) of a qubit can therefore be any quantum superposition (3.2.17) of these states. A qubit is therefore the quantum
analogue of a classical bit, which can only take the values 0 or 1.

[SOURCE: ISO/IEC 4879:2024, 3.3.3, modified – In Note 3, the last sentence is added; Notes 4-6 to entry
omitted]
3.2.413.2.29
3.2.42
qudit
quantum dit
quantum system (3.2.7) with n basisn basis states (3.2.15) where n is an integer greater than or equal two

Note 1 to entry: Qudit stands for quantum (3.2.6(3.2.6)) dit or quantum n-level system.
Note 2 to entry: Qudit is an n-fold unit of quantum information (3.2.30).
Field Code Changed
Note 5 3 to entry: Qubit (3.2.28) is a special case of qudit with n equal to 2.

[SOURCE: ISO/IEC 4879:2024, 3.3.4, modified – Notes 3, 4, 6, 7 to entry omitted]
3.2.433.2.30
3.2.44
quantum information
information contained or encoded in a quantum state (3.2.14).
Note 1 to entry: Quantum information may be transformed via quantum (3.2.6(3.2.6)) operations and processes.

[SOURCE: ISO/IEC 4879:2024, 3.3.1]

3.3 Phenomena resulting from quantum effects
3.3.1
plasmon
quantum (3.2.6) of collective electron oscillations in a metal or a semiconductor
Note 1 to entry: In condensed-matter physics, a plasmon is commonly described as a quasiparticle associated with a
collective oscillation of the electron gas.
[SOURCE: ISO 21466:2019, 3.37, modified – Notes 1 to entry added]
3.3.2
3.3.3
surface plasmon
plasmon (3.3.1) corresponding to a collective oscillation of free electrons bound to and propagating along the
surface of a metal, stimulated by electromagnetic waves

Note 1 to entry: Surface plasmons are typically confined to the interface between the metal and a dielectric and
propagate along that surface.
Note 2 to entry: Surface plasmons are central to plasmonics (3.4.3.12), nanophotonics (3.4.3.9), and sensing
technologies, enabling applications such as enhanced spectroscopies, single-photon sources, and quantum sensing
(3.4.5.3.1).
Field Code Changed
3.3.43.3.3
surface plasmon resonance
resonant excitation of surface plasmons (3.3.2) by an external electromagnetic field
Note 1 to entry: Surface plasmon resonance is widely used in biosensing and optical detection due to its high sensitivity
to changes in the local refractive index near the metal surface.
3.3.53.3.4
magnon
quantum (3.2.6) of a spin wave in a magnetically ordered material
Note 1 to entry: In condensed-matter physics, a magnon is commonly described as a quasiparticle associated with a
collective excitation of electron spins.
3.3.63.3.5
ballistic transport
regime of carrier motion in which particles propagate through the system without scattering, typically
occurring when the characteristic dimensions of the system are smaller than the carriers’ mean free path or
momentum relaxation length
Note 1 to entry: The ballistic transport regime is significant in nanoscale systems, such as quantum wires
(3.4.2.4(3.4.2.4),), where quantum effects dominate over classical scattering processes.

3.3.73.3.6
coherent transport
regime of particle or wave propagation in which quantum phase coherence (3.2.21) is preserved throughout
the transport process, typically occurring when the dimensions of the system are smaller than the phase
coherence length
Note 1 to entry: Coherent transport enables interference effects and is central to phenomena such as conductance
quantization (3.2.13) in mesoscopic and nanoscale systems.
Field Code Changed
3.3.83.3.7
Coulomb blockade
suppression of electron tunnelling into a small conductive region, such as a quantum dot (3.4.2.3), through a
tunnel junction, caused by Coulomb repulsion and the Pauli exclusion principle
Note 1 to entry: Coulomb blockade arises from charge quantization (3.2.13) and is fundamental to the operation of
single-electron electronics (3.4.3.2), where it enables control of electrical transport one electron at a time.
3.3.93.3.8
quantum Hall effect
QHE
quantization (3.2.13) of Hall conductance in two-dimensional electron systems under low temperatures and
strong magnetic fields, where the conductance takes discrete values that are integer or fractional multiples of
the conductance quantum (3.2.5)
Field Code Changed
Note 1 to entry: When the quantized values correspond to integers, the phenomenon is known as the “integer quantum
Hall effect”; when they are rational fractions, it is referred to as the “fractional quantum Hall effect”, arising from electron–
electron interactions and correlated quantum states (3.2.14).
Field Code Changed
Note 2 to entry: Related variants of the QHE also exist without an externally applied magnetic field. For example, the
anomalous quantum Hall effect (AQHE) in magnetic topological insulators (3.4.2.10) arises from intrinsic magnetic order
Field Code Changed
and strong spin–orbit coupling.

Note 3 to entry: Spin Hall effect (3.3.14) is a distinct phenomenon that also produces a transverse response but does not
require an external magnetic field or quantization (3.2.13).
Field Code Changed
3.3.103.3.9
giant magnetoresistance
GMR
quantum effect (3.2.8) in which the electrical resistance of a material changes significantly in response to an
applied magnetic field due to spin-dependent electron scattering

Note 1 to entry: GMR typically occurs in multilayer heterostructures composed of alternating ferromagnetic and
nonmagnetic conductive layers, where the relative alignment of magnetic moments influences resistance. It is widely
used in magnetic read heads, sensors, and spintronic devices.

Note 2 to entry: GMR is distinct from tunnelling magnetoresistance (3.3.10), which involves spin-dependent tunnelling
through an insulating barrier, and colossal magnetoresistance (3.3.11), which occurs in bulk correlated materials.
Field Code Changed
3.3.113.3.10
tunnelling magnetoresistance
TMR
quantum effect (3.2.8) in which the electrical resistance of a junction composed of two ferromagnetic layers
separated by a thin insulating barrier depends on the relative alignment of the magnetic moments, due to spin-
dependent quantum tunnelling (3.2.25) of electrons
Field Code Changed
Note 1 to entry: TMR is typically observed in magnetic tunnel junctions (xx), where resistance is lower when the
magnetizations of the two ferromagnetic layers are parallel and higher when they are antiparallel. It is exploited in
spintronics (3.4.3.7) applications such as magnetic random-access memory (MRAM), sensors, and hard disk drive read
heads.
Note 2 to entry: TMR is distinct from giant magnetoresistance (3.3.9), which arises from spin-dependent scattering in
conductive multilayers, and colossal magnetoresistance (3.3.11), which occurs in bulk correlated materials.
Field Code Changed
3.3.123.3.11
colossal magnetoresistance
CMR
quantum effect (3.2.8) observed in certain bulk materials, where strong electron correlations and coupling
between charge, spin, orbital, and lattice degrees of freedom lead to extremely large changes in electrical
resistance in response to a magnetic field

Note 1 to entry: CMR is typically observed in manganese oxides and related strongly correlated electron systems. It can
produce resistance changes several orders of magnitude greater than those observed in giant magnetoresistance (3.3.9)
Field Code Changed
and is studied for applications in magnetic sensors and spintronic devices.

Note 2 to entry: Unlike giant magnetoresistance and tunnelling magnetoresistance (3.3.10), which arise in engineered
multilayer junctions, CMR is an intrinsic property of bulk materials.
3.3.133.3.12
3.3.14
spin-transfer torque
STT
quantum effect (3.2.8), in which a spin-polarized electric current transfers angular momentum to the
magnetization of a ferromagnetic material, exerting a torque that can reorient the magnetization

Note 1 to entry: Spin-transfer torque is exploited in spintronic devices such as spin-transfer torque magnetic random-
access memory (STT-MRAM).
3.3.153.3.13
3.3.16
spin-orbit torque
SOT
quantum effect (3.2.8), in which spin–orbit coupling converts an electric current into a spin current that exerts
a torque on the magnetization of an adjacent ferromagnetic layer

Note 1 to entry: Spin–-orbit torque typically arises from the spin Hall effect (3.3.14) or from interfacial mechanisms
such as the Rashba–Edelstein effect. It enables efficient magnetization switching in spintronic devices such as spin-orbit
torque magnetic random-access memory (SOT-MRAM).
3.3.173.3.14
3.3.18
spin Hall effect
quantum effect (3.2.8), in which an electric current in a material with strong spin–orbit coupling generates a
transverse spin current, leading to the accumulation of spins of opposite orientation on opposite sides of the
material
Note 1 to entry: Spin Hall effect does not require an external magnetic field and is distinct from the quantum Hall effect
(3.3.8).
Field Code Changed
Note 2 to entry: Spin Hall effect provides a mechanism for spin–-orbit torque (3.3.13) and for generating spin currents
in spintronic devices.
3.4 Quantum technologies: materials, devices, and applications
3.4.1 General quantum technology terms
3.4.1.1
quantum technologies
broad class of technologies that utilize quantum phenomena (3.2.8) to achieve functionality or performance
beyond what is possible with classical physics, including but not limited to quantum information technologies
(3.4.1.2)
Field Code Changed
Note 1 to entry: In addition to quantum information technologies, quantum technologies include quantum-enabled
devices that do not explicitly process information, such as quantum-limited sensors (3.4.5.3.3) and detectors
(3.4.5.3.4(3.4.5.3.4),), as well as quantum-enhanced (3.2.11) classical devices like superconducting quantum interference
(3.2.27) devices (SQUIDs) and atomic clocks. The term also encompasses materials and systems whose functionality
depends on quantum behaviorbehaviour, even if they are not framed within an information-processing context.

3.4.1.2
quantum information technologies
QIT
technologies that apply principles of quantum information (3.2.30) science, such as superposition (3.2.17),
entanglement (3.2.22), and quantum measurement (3.2.24), to process, transmit, or extract information in
ways that surpass classical capabilities

Note 1 to entry: Quantum information technologies represent a distinct subset of quantum technologies (3.4.1.1),
focused on high-performance computing and simulation, secure communication, and advanced sensing. Examples
include quantum computers (3.4.5.1.5) and simulators (3.4.5.1.17) for computation and modelling, quantum key
distribution (QKD) systems (3.4.5.2.6) for secure communication, and quantum sensors (3.4.5.3.2) for precision
Field Code Changed
measurements.
Note 2 to entry: These technologies can be realized on a variety of physical platforms, including superconducting qubits
(3.4.4.4), trapped-ion qubits (3.4.4.5), neutral-atom qubits (3.4.4.6), photonic qubits (3.4.4.7), spin qubits (),(3.4.4.3), and
defect-based qubits such as NV centres in diamond (3.4.2.7).
Field Code Changed
3.4.1.3
quantum information processing
process, algorithm (3.1.4), or computation that stores and processes quantum information (3.2.30) using, in
an essential way, properties such as quantum superposition (3.2.17) and quantum entanglement (3.2.22)
Note 1 to entry: Examples of common quantum processes where fidelities are reported include quantum gates
(3.4.5.1.2) and quantum measurements (3.2.24).
[SOURCE: ISO/IEC 4879:2024, 3.4.1]
3.4.1.4
3.4.1.5
quantum processor
tangible device that performs quantum information processing (3.4.1.3)

[SOURCE: ISO/IEC 4879:2024, 3.4.8]

3.4.2 Material platforms
3.4.2.1
quantum materials
material systems whose properties and behaviorbehaviour are fundamentally governed or significantly
influenced by quantum effects (3.2.8), such as quantum entanglement (3.2.22) and quantum coherence (3.2.18),
and that cannot be fully explained by classical physics

Note 1: to entry: Quantum materials are often characterized by strong electronic correlations or nontrivial topological
band structures, giving rise to emergent phenomena such as superconductivity, the surface conduction
behaviorbehaviour of topological insulators (3.4.2.8), and quantum spin liquid (3.4.2.11) states.

Note 2: to entry: Examples include superconductors, graphene, transition metal dichalcogenides, and Mott insulators,
each demonstrating quantum phenomena (3.2.8) such as topological surface states, electronic band inversion, or strong
electron–electron interactions.

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