87Rb isoclinic point thermometry

The concept of atomic thermometry is demonstrated in an experimental system consisting of two lasers frequency stabilized using FM spectroscopy. Utilizing the temperature insensitivity of the ⁸⁷Rb D₁ isoclinic point, a reference laser is beat against a second laser locked to an atomic transition whose frequency is strongly dependent on the vapor temperature. The data presented here indicates that thermal fluctuations down to the mK level could potentially be sensed. This concept may be useful to obtain improved long term performance in Rb vapor cell atomic clocks.