Tight bound on finiteresolution quantum thermometry at low temperatures
Abstract
Precise thermometry is of wide importance in science and technology in general and in quantum systems in particular. Here, we investigate fundamental precision limits for thermometry on cold quantum systems, taking into account constraints due to finite measurement resolution. We derive a tight bound on the optimal precision scaling with temperature, as the temperature approaches zero. The bound demonstrates that under finite resolution, the variance in any temperature estimate must decrease slower than linearly. This scaling can be saturated by monitoring the nonequilibrium dynamics of a singlequbit probe. We support this finding by numerical simulations of a spinboson model. In particular, this shows that thermometry with a vanishing absolute error at low temperature is possible with finite resolution, answering an interesting question left open by previous work. Our results are relevant both fundamentally, as they illuminate the ultimate limits to quantum thermometry, and practically, in guiding the development of sensitive thermometric techniques applicable at ultracold temperatures.
 Publication:

Physical Review Research
 Pub Date:
 September 2020
 DOI:
 10.1103/PhysRevResearch.2.033394
 arXiv:
 arXiv:2001.04096
 Bibcode:
 2020PhRvR...2c3394J
 Keywords:

 Quantum Physics
 EPrint:
 10+3 pages, 3 figures