Using Polarons for sub-nK Quantum Nondemolition Thermometry in a Bose-Einstein Condensate

Area of Science:

• Quantum physics
• Atomic physics
• Condensed matter physics

Background:

• Bose-Einstein condensates (BECs) are crucial quantum systems requiring precise thermometry.
• Existing thermometry methods can be destructive or lack sufficient precision.

Purpose of the Study:

• To introduce a novel, minimally disturbing method for sub-nanokelvin thermometry in BECs.
• To establish a quantum thermometry technique based on the Bose polaron model.

Main Methods:

• Utilizing an impurity atom within the BEC as a thermometer.
• Detecting temperature fluctuations via measurements of the impurity's position and momentum.
• Applying quantum parameter estimation and open quantum systems theory for general solutions.

Main Results:

• The proposed method offers a non-demolition temperature measurement with minimal backaction on the BEC.
• The technique avoids simplifying assumptions like impurity thermalization or weak dissipation.
• Demonstrated feasibility with realistic experimental parameters, competing with destructive methods.

Conclusions:

• This novel approach enables high-precision, non-destructive thermometry in BECs.
• The Bose polaron thermometer provides a powerful tool for quantum gas research.
• The method is robust and applicable even with suboptimal measurement strategies.