Standards Development

Scope

This document gives definitions for general vocabulary in the field of quantum technologies.

The terms described here include supporting terms needed to define general quantities and those
that are widely used throughout quantum technologies, especially including fundamental terms from
quantum information science. They are commonly presented in scientific textbooks and are familiar
to quantum scientists and technologists across disciplines. In these senses, these terms are
considered fundamental or general.

The scope excludes specialised terms specific to key individual subfields such as quantum
computing, quantum communications and quantum sensing, as well as specialised terms focussed
on details of enabling and cross-cutting devices and technology (as opposed to higher level terms
that apply to their broader application).

Purpose

Need: Standardised terminology will be essential for a wide range of activities connected with quantum technology standards. Due to the wide range of disparate hardware and software platforms current being used to develop quantum technology systems, standardised terminology will aid communication between different communities of quantum technology developers, and between quantum technology developers and end-user stakeholders. Terminology standards will also be crucial for the development of reliable measurement and test methods for characterization, benchmarking and evaluation, and quality assurance processes. It was recommended by JTC 3 ad hoc Group 2 Terminology and metrics that terms that fall under wider general vocabulary should be developed in a separate vocabulary document from terms related specifically to quantum technology subfields like quantum computing.

Benefit: The proposed standard has two primary purposes—

1. While application-specific terminology will be developed in more narrowly focussed groups within JTC3, it will be important for interoperability that these build, wherever possible, on a consistent foundation of fundamental and cross-cutting terms, and developing this foundation is one of the primary aims of the proposed standard.

2. The related General Quantities standard (inspired by the ISO 80000 series), which will be a key ingredient for metrology (characterization, benchmarking and evaluation), will also crucially build on definitions involving terms which do not fall into the category of quantities.

3. The proposed General Vocabulary document complements the General Quantities document also by addressing different target audiences, namely the wider community (for this document), rather than the primarily the community of quantum technology and metrology experts involved in developing and validating quantum technologies (for the General Quantities document).

Timing: It is appropriate to commence work on the proposed standard at the current time because

— 1. The quantum technology industry is now expanding at pace and beginning to incorporate a wider range of stakeholder groups (e.g., researchers, technology developers, suppliers, investors, end users and the wider public). The proposed general vocabulary standard will help streamline communication and understanding between these different stakeholder groups.

2. Since towards the end of the development cycle for the quantum computing vocabulary standard ISO/IEC 4879, there has already been significant momentum building for expanding its work to encompass terms across the wider field of quantum technology as a whole. As published, ISO/IEC 4879 contains significant gaps in coverage of definitions for general terms, e.g., including general mathematical concepts, general methods for encoding information in quantum systems, and general higher-level terms related to quantum technology hardware platforms.

3. Work on standardised definitions of quantities in quantum technologies is already well underway in CEN-CENELEC JTC22, and is expected to move across to development in JTC 3. It is important to start developing already the complementary non-quantities vocabulary that will underpin these general quantities definitions to lay a reliable foundation for the general quantities document as it is being developed.

Project plan: A selection of more foundational terms included in ISO/IEC 4879 will form the seed of the proposed Quantum Technologies General Vocabulary standard. Terms brought over from ISO/IEC 4879 will likely include:

ISO/IEC 4879:2024, 3.2 Quantum physics background—

• Hilbert space

• operator

• quantum physics/quantum mechanics

• quantum, adjective

• quantum, noun

• quantum system

• quantum state

• quantum superposition

• basis states

• quantum entanglement

• quantum operator

• Hamiltonian

• eigenstate

• eigenvalue

• eigenspace

• quantum measurement

• projective measurement

• quantum coherence

• decoherence

• coherence time

• relaxation time

ISO/IEC 4879:2024, 3.3 Quantum information—

• quantum information

• quantum encoding

• qubit

• qudit

• physical qudit

• state fidelity

• fidelity

• process fidelity

The proposed standard will develop a concept system for Quantum Technologies General Vocabulary. Examples of areas which will be explored to identify additional terms that fit within this concept system include:

• Mathematical concepts underpinning general methods for encoding information in quantum systems [e.g., vector space, inner product, vector norm, Hermitian conjugate, Hermitian operator]

• General methods for encoding information in quantum systems (quantum information science and engineering) [e.g., no-cloning theorem, optimal state discrimination, coherent states, squeezed states]

• General terms related to broad categories of quantum technology hardware platforms, such as photonic, solid-state and atomic quantum platforms [e.g., quantum dot, cavity quantum electrodynamics], as opposed to more specialised terms specific to individual hardware platforms

• Terms needed to explain quantities included in the proposed General Quantities document [e.g., metric, distance measure]

An illustrative outline for the proposed standard is attached as an Annex to this NP.

It is expected that overlaps may emerge between the proposed General Vocabulary document, the proposed General Quantities document, and other application-specific vocabulary and quantities documents within JTC3, so identifying characteristics to separate terms and managing separations will need to be adjudicated in concert with other terminology projects.

The General Vocabulary project team shall work with the parent working group and any other relevant advisory level groups to develop a means to coordinate and facilitate the distribution and dispensation of terms, across liaisons both within and external to JTC3.