| Autor: |
Hovhannisyan, Karen V., Jørgensen, Mathias R., Landi, Gabriel T., Alhambra, Álvaro M., Brask, Jonatan B., Perarnau-Llobet, Martí |
| Rok vydání: |
2020 |
| Předmět: |
|
| Zdroj: |
PRX Quantum 2, 020322 (2021) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PRXQuantum.2.020322 |
| Popis: |
Precise thermometry for quantum systems is important to the development of new technology, and understanding the ultimate limits to precision presents a fundamental challenge. It is well known that optimal thermometry requires projective measurements of the total energy of the sample. However, this is infeasible in even moderately-sized systems, where realistic energy measurements will necessarily involve some coarse graining. Here, we explore the precision limits for temperature estimation when only coarse-grained measurements are available. Utilizing tools from signal processing, we derive the structure of optimal coarse-grained measurements and find that good temperature estimates can generally be attained even with a small number of outcomes. We apply our results to many-body systems and nonequilibrium thermometry. For the former, we focus on interacting spin lattices, both at and away from criticality, and find that the Fisher-information scaling with system size is unchanged after coarse-graining. For the latter, we consider a probe of given dimension interacting with the sample, followed by a measurement of the probe. We derive an upper bound on arbitrary, nonequilibrium strategies for such probe-based thermometry and illustrate it for thermometry on a Bose-Einstein condensate using an atomic quantum-dot probe. |
| Databáze: |
arXiv |
| Externí odkaz: |
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