The Bose polaron as thermometer of a trapped Bose gas: a quantum Monte Carlo study

Fuente: arXiv
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Autores principales: Wasak, Tomasz, Pascual, Gerard, Astrakharchik, Gregory E., Boronat, Jordi, Negretti, Antonio
Formato: Preprint
Publicado: 2025
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author Wasak, Tomasz
Pascual, Gerard
Astrakharchik, Gregory E.
Boronat, Jordi
Negretti, Antonio
author_facet Wasak, Tomasz
Pascual, Gerard
Astrakharchik, Gregory E.
Boronat, Jordi
Negretti, Antonio
contents Quantum impurities interacting with quantum environments offer unique insights into many-body systems. Here, we explore the thermometric potential of a neutral impurity immersed in a harmonically trapped bosonic quantum gas below the Bose-Einstein condensation critical temperature $T_c$. Using ab-initio Path Integral Monte Carlo simulations at finite temperatures, we analyze the impurity's sensitivity to temperature changes by exploiting experimentally accessible observables such as its spatial distribution. Our results, covering a temperature range of $-1.1 \leqslant T/T_c \leqslant 0.9$, reveal that the impurity outperforms estimations based on a one-species bath at lower temperatures, achieving relative precision of 3-4\% for 1000 measurement repetitions. While non-zero boson-impurity interaction strength $g_{BI}$ slightly reduces the accuracy, the impurity's performance remains robust, especially in the low-temperature regime $T/T_c \lesssim 0.45$ withing the analyzed interaction strengths $0 \leqslant g_{BI}/g \leqslant 5$, where $g$ is the boson-boson coupling. We confirm that quantum optical models can capture rather well the dependence of the temperature sensor on the impurity-gas interaction. Although our findings are in qualitative agreement with previous studies, our Monte Carlo simulations offer improved precision. We find that the maximum likelihood estimation protocol approaches the precision comparable to the limit set by the Quantum Fisher Information bound. Finally, using the Hellinger distance method, we directly extract the Fisher information and find that, by exploiting the extremum order statistics, impurities far from the trap center are more sensitive to thermal effects than those close to the trap center.
format Preprint
id arxiv_https___arxiv_org_abs_2503_04553
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Bose polaron as thermometer of a trapped Bose gas: a quantum Monte Carlo study
Wasak, Tomasz
Pascual, Gerard
Astrakharchik, Gregory E.
Boronat, Jordi
Negretti, Antonio
Quantum Gases
Quantum impurities interacting with quantum environments offer unique insights into many-body systems. Here, we explore the thermometric potential of a neutral impurity immersed in a harmonically trapped bosonic quantum gas below the Bose-Einstein condensation critical temperature $T_c$. Using ab-initio Path Integral Monte Carlo simulations at finite temperatures, we analyze the impurity's sensitivity to temperature changes by exploiting experimentally accessible observables such as its spatial distribution. Our results, covering a temperature range of $-1.1 \leqslant T/T_c \leqslant 0.9$, reveal that the impurity outperforms estimations based on a one-species bath at lower temperatures, achieving relative precision of 3-4\% for 1000 measurement repetitions. While non-zero boson-impurity interaction strength $g_{BI}$ slightly reduces the accuracy, the impurity's performance remains robust, especially in the low-temperature regime $T/T_c \lesssim 0.45$ withing the analyzed interaction strengths $0 \leqslant g_{BI}/g \leqslant 5$, where $g$ is the boson-boson coupling. We confirm that quantum optical models can capture rather well the dependence of the temperature sensor on the impurity-gas interaction. Although our findings are in qualitative agreement with previous studies, our Monte Carlo simulations offer improved precision. We find that the maximum likelihood estimation protocol approaches the precision comparable to the limit set by the Quantum Fisher Information bound. Finally, using the Hellinger distance method, we directly extract the Fisher information and find that, by exploiting the extremum order statistics, impurities far from the trap center are more sensitive to thermal effects than those close to the trap center.
title The Bose polaron as thermometer of a trapped Bose gas: a quantum Monte Carlo study
topic Quantum Gases
url https://arxiv.org/abs/2503.04553