Invited Talk: Compact Blackbody Radiation Atomic Sensor (CoBRAS), Quantum Thermometry with Vapor Cell Atoms

Accurate remote sensing data products require thermometers which are robust to the challenging engineering demands of space flight without exhibiting long-term drift. The NIST Fundamental Thermodynamics group is leveraging the physical properties of atoms to provide such accurate metrology of radiative temperature. Atoms are quantum systems whose interactions with electromagnetic radiation have been characterized with exquisite precision and, in many cases, are amenable to ab initio calculation. This talk will describe a Compact Blackbody Radiation Atomic Sensor, or CoBRAS, which uses fluorescence detection of optically excited atoms in vapor cells. A CoBRAS temperature measurement is fast, with statistical uncertainty as low as 0.1% in one second. We resolve temperature with a precision of 0.04% in the range 308-344 K when averaging for several seconds. Additionally, we describe an extension to this measurement scheme where the device operates as a self-calibrated, or primary, thermometer. We make progress toward realizing a primary thermometer by demonstrating a temperature-dependent self-consistent calibration scheme, with temperature accuracy of the order of 1% limited by the uncertainty in atomic transition dipole matrix elements.