Enhancement of low-temperature thermometry by strong coupling

Correa, Luis A.; Perarnau-Llobet, Mart�; Hovhannisyan, Karen V.; Mehboudi, Mohammad; Hern�ndez-Santana, Senaida; Sanpera, Anna

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.

Citation

Correa, L. A., Perarnau-Llobet, M., Hovhannisyan, K. V., Mehboudi, M., Hernández-Santana, S., & Sanpera, A. (2017). Enhancement of low-temperature thermometry by strong coupling. Physical Review A, 96(6), Article 062103. https://doi.org/10.1103/PhysRevA.96.062103

• Journal Article Type: Article
• Acceptance Date: Nov 16, 2017
• Publication Date: Dec 4, 2017
• Deposit Date: Dec 7, 2017
• Publicly Available Date: Dec 7, 2017
• Journal: Physical Review A
• Print ISSN: 2469-9926
• Electronic ISSN: 1094-1622
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 96
• Issue: 6
• Article Number: 062103
• DOI: https://doi.org/10.1103/PhysRevA.96.062103
• Public URL: https://nottingham-repository.worktribe.com/output/898559
• Publisher URL: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.96.062103
• Additional Information: ©2017 American Physical Society