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Abstract The “Quantum Electro-Mechanical Metrology Suite” (QEMMS) is being designed and built at the National Institute of Standards and Technology. It includes a Kibble balance, a graphene quantum Hall resistance array and a Josephson voltage system, so that it is a new primary standard for the unit of mass, the kilogram, directly traceable to the International System of Units (SI) based on quantum constants. We are targeting a measurement range of 10 g to 200 g and optimize the design for a relative combined uncertainty of 2 × 10 − 8 $2\times 10^{-8}$ for masses of 100 g. QEMMS will be developed as an open hardware and software design. In this article, we focus on the design of an enhanced moving and weighing mechanism for the QEMMS based on flexure pivots.

The "Quantum Electro-Mechanical Metrology Suite" (QEMMS) is being designed and built at the National Institute of Standards and Technology. It includes a Kibble balance, a graphene quantum Hall resistance array and a Josephson voltage system, so that it is a new primary standard for the unit of mass, the kilogram, directly traceable to the International System of Units (SI) based on quantum constants. We are targeting a measurement range of 10 g to 200 g and optimize the design for a relative combined uncertainty of 2 × 10 − 8 for masses of 100 g. QEMMS will be developed as an open hardware and software design. In this article, we focus on the design of an enhanced moving and weighing mechanism for the QEMMS based on flexure pivots. [ABSTRACT FROM AUTHOR]

Optical gas refractometry has enabled new pressure standards to be developed based on a dual Fixed Length Optical Cavity (FLOC) system. NIST in CRADA (collaboration research and development agreement) partnership with MKS Instruments has created a portable FLOC pressure standard based on gas refractivity. A key challenge for accurate measurements is the characterization of cavity distortions when pressurized. A method for determination of the distortion constants is presented based on using two gases of known refractive index. Using this two-gas technique, the distortions on the portable FLOC pressure standard are corrected so that this correction contributes no more than 1 μPa/Pa of uncertainty (k = 1).

This article gives an overview of the new SI and a few details as to how it was set up. Those interested in the story of how the kilogram was fixed by tying it to the Planck constant can go straight to Section 5. Otherwise, apart from the introduction given as Section 1 which also presents excerpts from the relevant official documents on the key aspects of the new system, Section 2 gives a brief timeline of the history of the decimal metric system, Section 3 gives a few details of the procedural steps—from the setting up of a standard of measurement to its percolation to the public, taking the time standard as an example, and Section 4 attempts to give a flavour of the actual process of the setting up of a standard. [ABSTRACT FROM AUTHOR]

Cold atom vacuum metrology is a technique for linking science and applications of cold atom and vacuum sensing based on a fundamental atomic property, the collision cross-section. It is expected to establish a quantum ultra-high/extreme-high vacuum primary standard. This paper summarises and analyses in detail the research advances of the technique. It focuses on the design and optimization of experimental apparatus in the cold atom capture process and the measurement of critical parameters during the observation process for the lifetime of cold atoms. In addition, the comparison between standards is presented to verify the performance of the new standard. It concludes with an outlook on the breakthrough points and development directions of the technique for practical applications. • The designs and improvements of the cold atom apparatus units to meet the vacuum measurement requirements are analysed. • The determinations of critical parameters for the cold atom vacuum measurement in different atomic traps are reviewed. • Further research directions for cold atom vacuum metrology towards practical applications are proposed. [ABSTRACT FROM AUTHOR]

The quantum Hall effect (QHE), and devices reliant on it, will continue to serve as the foundation of the ohm while also expanding its territory into other SI derived units. The foundation, evolution, and significance of all of these devices exhibiting some form of the QHE will be described in the context of optimizing future electrical resistance standards. As the world adapts to using the quantum SI, it remains essential that the global metrology community pushes forth and continues to innovate and produce new technologies for disseminating the ohm and other electrical units.