A portable Rb quantum pressure standard for inter-standard validation

Single atoms are ideal for metrology since they are ageless sensors operating on immutable laws of nature. Using atoms to measure vacuum pressure hinges on knowing the thermally-averaged loss cross section for collisions between the sensor atoms and the background gas particles. There are three ways to determine it: (1) estimate it using ab initio computations, (2) calibrate it using a known pressure for a known species against another accepted standard, or (3) measure it directly using the sensor atom and quantum diffractive universality (QDU).[1,2] We are collaborating with researchers at the US National Institute of Standards and Technology (NIST) to compare these three methods directly. To achieve this, we are building a portable version of our Rb-based pressure sensor calibrated using QDU (3) to send to NIST. It will be compared with their Li-based sensor (calibrated with (1)) and their orifice flow standard (2). This new apparatus uses magnetic quadrupole coils optimized to minimize thermal perturbations while maximizing the field gradient. The cooling, trapping, and detection light will be generated with an offset-locked laser and EOM to ease configuration.

[1] Booth, J. L. et al, 2019, New J. Physics, 21, 102001.

[2] Shen, P., et al, 2020, Metrologia, 57, 025015.