Towards quantum-based realisations of the pascal

Short Name: QuantumPascal, Project Number: 18SIB04
Image of a Fabry-Pérot resonator used at CNAM for photon-based pressure - Courtesy of CNAM
Fabry-Pérot resonator used at CNAM for photon-based pressure - Courtesy of Conservatoire National des Arts et Métiers (CNAM)

Quantum-based realisations of the pascal expected to yield new ways to calibrate gas pressure measurements

Despite minimal improvements in performance over decades, industrial and scientific measurements of gas pressure are still made with manometers containing toxic mercury. Piston gauges are more accurate but require exchange of weights during calibration and can be slow, bulky, complex, and require additional methods below 3 kilopascals. In theory, the drawbacks could be fixed using photon-based devices that use helium or other gases as the calculable reference substance. Miniaturisation could also enable faster, cheaper, calibration-free measurements.


The project has developed photon-based standards, applying quantum methods showing potential as a replacement primary standard of the SI unit of pressure, the pascal. Various methods were tried, some pioneering, combined with new calculations of thermodynamic and electromagnetic gas properties. Performance was then compared with current primary pressure standards.

Technologies developed will be promoted to end users and standards bodies: as quantum-based realisations of the pascal could enable more accurate and versatile pressure measurement methods, to benefit other fields of metrology, wider science, industry and manufacturing.


Project website
An optical pascal in Sweden

Journal of Optics

Ability of gas modulation to reduce the pickup of drifts in refractometry

Journal of the Optical Society of America B

Path-Integral Calculation of the Second Dielectric and Refractivity Virial Coefficients of Helium, Neon, and Argon

Journal of Research of the National Institute of Standards and Technology

Other Participants
Fondazione Bruno Kessler (Italy)
Umeå Universitet (Sweden)
University College London (United Kingdom)
Uniwersytet Warszawski (Poland)
WIKA Alexander Wiegand SE & Co. KG (Germany)