The cold atom physics research team from Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) has successfully realized fast temperature measurement and simulated Maxwell’s demon in cold atoms. The related research results have been published in Photonics Research on July 27, 2022.

The rapid development of quantum technologies with cold atom ensembles, including quantum precision measurement, quantum sensing , quantum simulation, and quantum information, raises emerging requirements for fast temperature measurement with minimal disturbance and an effective method of sorting out relatively colder atoms.

The researcher team demonstrates deterministic measurement of temperature within less than 1 ms detection time and effective filtering of colder atoms with temperature less than 1 μK starting from an ensemble with about 20 μK. The essential procedure consists of a well calibrated labeling operation of atoms and nearly nondestructive detection with continuous optical pulses, relying on the polarization control of the atoms’ internal states and a cycling transition.

Moreover, the researcher team has realized a velocity-dependent labeling effect by adjusting the labeling process, in the style of Maxwell’s demon thought experiment. This experiment does not require subtle quantum coherence effects or delicate quantum manipulation techniques.

Fig. 1. Schematic diagrams of experimental setup and theory curve. (Image by SIOM)

Fig. 2. The experimental principle and experimental data for simulating Maxwell's demon. (Image by SIOM)