Enhancement of low-temperature thermometry by strong coupling

Correa, Luis A. and Perarnau-Llobet, Martí and Hovhannisyan, Karen V. and Mehboudi, Mohammad and Hernández-Santana, Senaida and Sanpera, Anna (2017) Enhancement of low-temperature thermometry by strong coupling. Physical Review A, 96 (6). 062103/1-062103/12. ISSN 1094-1622

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Abstract

We consider the problem of estimating the temperature T of a very cold equilibrium sample. The temperature estimates are drawn from measurements performed on a quantum Brownian probe strongly coupled to it. We model this scenario by resorting to the canonical Caldeira-Leggett Hamiltonian and find analytically the exact stationary state of the probe for arbitrary coupling strength. In general, the probe does not reach thermal equilibrium with the sample, due to their nonperturbative interaction. We argue that this is advantageous for low-temperature thermometry, as we show in our model that (i) the thermometric precision at low T can be significantly enhanced by strengthening the probe-sampling coupling, (ii) the variance of a suitable quadrature of our Brownian thermometer can yield temperature estimates with nearly minimal statistical uncertainty, and (iii) the spectral density of the probe-sample coupling may be engineered to further improve thermometric performance. These observations may find applications in practical nanoscale thermometry at low temperatures—a regime which is particularly relevant to quantum technologies.

Item Type: Article
Additional Information: ©2017 American Physical Society
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Mathematical Sciences
Identification Number: 10.1103/PhysRevA.96.062103
Depositing User: Correa Marichal, Luis
Date Deposited: 07 Dec 2017 09:19
Last Modified: 07 Dec 2017 10:56
URI: http://eprints.nottingham.ac.uk/id/eprint/48572

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