The International System of Units (SI) is the world's most widely used system of measurement, used every day in commerce and science, and is the modern form of the metric system. It currently comprises the meter (m), the kilogram (kg), the second (s), the ampere (A), the kelvin (K), the candela (cd) and the mole (mol)). The system is changing though, units and unit definitions are modified through international agreements as the technology of measurement progresses, and as the precision of measurements improves. The SI is now being redefined based on constants of nature and their realization by quantum standards. Therefore, the underlying physics and technologies will receive increasing interest, and not only in the metrology community but in all fields of science. This book introduces and explains the applications of modern physics concepts to metrology, the science and the applications of measurements. A special focus is made on the use of quantum standards for the realization of the forthcoming new SI (the international system of units). The basic physical phenomena are introduced on a level which provides comprehensive information for the experienced reader but also provides a guide for a more intense study of these phenomena for students.
Advances in quantum mechanics have long underpinned metrology by enabling practical realizations of units through quantum effects. With the 2019 SI revision, traceability is anchored in defined fundamental constants, reinforcing the quantum-mechanical basis of modern standards. In parallel, quantum technologies are transitioning from laboratory science to engineering and early industrial deployment, bringing familiar pressures for integration, reliability, cost reduction, supply-chain formation, and standardization. The direction of benefit is thus reversing: metrology and precision measurement are becoming enabling infrastructure for the industrialization of quantum technologies. Against this backdrop, this paper surveys the metrology and precision-measurement capabilities required across representative quantum-computing modalities and identifies where electrical and related metrology can contribute to the development, characterization, and reliable operation of quantum hardware. We then discuss cross-cutting measurement needs and standardization opportunities that recur across platforms, and note how similar frameworks can extend to emerging quantum-sensing applications.
The recent redefinition of the International System of Units in 2019 fixes the numerical values of seven defining constants, and links to them the definition of the seven fundamental units. Specifically, the fundamental constant related to the definition of the measurement unit for thermodynamic temperature (the kelvin) is the Boltzmann constant,
kB. Measurement of the Boltzmann constant is now done with classical methods. We propose an alternative method based on the measurement of the work done on a quantum system: we will take advantage of the Crooks-Tasaki fluctuation theorem and we will exploit an interferometric method to reduce the uncertainty in the measurement of
kB in specific temperature regimes, i.e. below 100 mK, that are challenging for the realization of the thermometric scale. The work
W done on a system of finite size and in contact with a thermal reservoir is a stochastic variable. Every time we repeat the protocol we will measure, in general, a different value for
W, following a probability distribution
P(W). The system considered is a qubit in contact with a thermal reservoir and we perform work on the open system varying a parameter
lambda(t) of the system Hamiltonian
H(lambda(t)). We will use an interferometric technique that takes advantage of an ancilla qubit for measuring the work
W. We collect the
W statistics to obtain
Pforward(W). The information on
kB is embedded in the magnitude of the inteferometric oscillations at precisely known frequencies. If, starting from the final state, we perform work by applying the inverse protocol $H(lambda(t)), with
lambda’(t)=lambda(−t), we will have, in general, a different probability distribution
Pbackward(W). The Crooks-Tasaki theorem connects
Pforward(W) with
Pbackward(W):
fracPforward(W)Pbackward(−W)=efracW−DeltaFkBT where
T is the temperature of the reservoir and
W−DeltaF is the energy dissipated in the forward protocol, being
DeltaF the difference between the initial and final free energy of the system. Eventually, we evaluate
kB by plotting the logarithm of the left-hand-side of the Crooks-Tasaki theorem equation for different values of
W at fixed
T. By evaluating the slope of the line $y= ln{frac{P_{forward}(W)}{P_{backward}(-W)}$ at fixed
T, we are able to estimate
kB. We note that larger slope values, corresponding to lower temperature, allow better estimation of
kB. We propose to use the electronic spin of a Nitrogen-Vacancy centre in diamond as the system qubit, and as an ancillary qubit the nuclear spin of the neighbouring Nitrogen atom. We perform work on the Nitrogen-Vacancy centre varying the intensity and direction of an oscillating magnetic field, taking advantage of the discretization of system energy levels and the not-adiabaticity of the process. This method will establish a quantitative link between the work done and the energy dissipated by a quantum task. Furthermore, this measurement reaches its optimum for very low temperatures (5-80 mK) typical of solid-state quantum computation, thus providing a primary thermometer for such applications.
Precision metrology has undergone a revolution thanks to quantum measurement techniques, which have made it possible to determine basic constants with previously unheard-of accuracy and to improve timekeeping. These techniques, which are based on the ideas of quantum physics, use entanglement, superposition, and quantum state interference to increase measurement accuracy beyond what is possible with classical approaches. the most recent advancements in high-precision quantum measurement methods, with an emphasis on how they can be used to determine fundamental constants like Planck's constant and the fine-structure constant. Additionally, atomic clocks and optical lattice clocks have advanced timekeeping by providing remarkably accurate time standards. There is also discussion of how quantum-enhanced sensors can improve temperature, electromagnetic field, and gravitational wave measurements. In order to redefine precision in science and industry, we conclude by outlining potential directions for incorporating quantum technologies into global metrology frameworks.
first_page settings Order Article Reprints Font Type: Arial Georgia Verdana Font Size: Aa Aa Aa Line Spacing: Column Width: Background: Open AccessAbstract Quantum Metrology and Relativistic Symmetries † by Marc-Thierry Jaekel 1 and Serge Reynaud 2,* 1 Laboratoire de Physique Théorique CNRS, ENS-PSL, UPMC-SU, F-75231 Paris, France 2 Laboratoire Kastler Brossel CNRS, ENS-PSL, UPMC-SU, Collège de France, F-75252 Paris, France * Author to whom correspondence should be addressed. † Presented at Symmetry 2017—The First International Conference on Symmetry, Barcelona, Spain, 16–18 October 2017. Proceedings 2018, 2(1), 41; https://doi.org/10.3390/proceedings2010041 Published: 3 January 2018 (This article belongs to the Proceedings of The First International Conference on Symmetry) Download Download PDF Download PDF with Cover Download XML Versions Notes Modern metrology is based on quantum and relativistic physics. The second is defined as a fixed integer number of periods of atomic caesium clocks while the meter is derived from the exact value fixed for the speed of light in vacuum c. Clock synchronization, distance measurement (ranging) or localization in space-time (GNSS localization) are built on the remote distribution of electromagnetic field phases. In 2018, the Planck constant h and elementary charge e should be defined to have exact values, replacing the old definitions of the kilogram and Ampere units.However, the quantum status of time, space and mass observables and its compatibility with relativistic symmetries remain open questions. We address this problem in a quantum algebraic approach where observable positions in space and time are defined so that they obey relativistic and quantum requirements [1]. A mass observable is defined which is no longer a constant as expected from its dimension with respect to dilatation.The commutators of quantum positions involve spin, and frame transformations to accelerated frames differ from their classical counterparts [2]. Relativistic symmetries nevertheless allow one to extend the covariance rules of general relativity to the quantum algebraic framework [3]. It leads to a quantum version of the Einstein equivalence principle identified to the transformation of the mass observable. ReferencesJaekel, M.-T.; Reynaud, S. Quantum Observables associated with Einstein Localisation. arXiv 1998, arXiv:quant-ph/9810027. [Google Scholar]Jaekel, M.-T.; Reynaud, S. Quantum algebraic representation of localization and motion of a Dirac electron. arXiv 2001, arXiv:quant-ph/0101121. [Google Scholar]Jaekel, M.-T.; Reynaud, S. Mass, inertia and gravitation. arXiv 2011, arXiv:0812.3936. [Google Scholar]Publisher's Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Share and Cite MDPI and ACS Style Jaekel, M.-T.; Reynaud, S. Quantum Metrology and Relativistic Symmetries. Proceedings 2018, 2, 41. https://doi.org/10.3390/proceedings2010041 AMA Style Jaekel M-T, Reynaud S. Quantum Metrology and Relativistic Symmetries. Proceedings. 2018; 2(1):41. https://doi.org/10.3390/proceedings2010041 Chicago/Turabian Style Jaekel, Marc-Thierry, and Serge Reynaud. 2018. "Quantum Metrology and Relativistic Symmetries" Proceedings 2, no. 1: 41. https://doi.org/10.3390/proceedings2010041 Find Other Styles Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here. Article Metrics No No Article Access Statistics Multiple requests from the same IP address are counted as one view.
Advances in quantum mechanics have long underpinned metrology by enabling practical realizations of units through quantum effects. With the 2019 SI revision, traceability is anchored in defined fundamental constants, reinforcing the quantum‐mechanical basis of modern standards. In parallel, quantum technologies are transitioning from laboratory science to engineering and early industrial deployment, bringing familiar pressures for integration, reliability, cost reduction, supply‐chain formation, and standardization. The direction of benefit is thus reversing: metrology and precision measurement are becoming enabling infrastructure for the industrialization of quantum technologies. Against this backdrop, this paper surveys the metrology and precision‐measurement capabilities required across representative quantum‐computing modalities and identifies where electrical and related metrology can contribute to the development, characterization, and reliable operation of quantum hardware. We then discuss cross‐cutting measurement needs and standardization opportunities that recur across platforms, and note how similar frameworks can extend to emerging quantum‐sensing applications. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.