%0 Journal Article
%J Quantum
%D 2018
%T Fluctuation-dissipation theorem for non-equilibrium quantum systems
%A Mehboudi, Mohammad
%A Sanpera, Anna
%A Parrondo, Juan M. R.
%B Quantum
%V 2
%P 66
%8 Dec-05-2019
%U https://quantum-journal.orghttps://quantum-journal.org/papers/q-2018-05-24-66/
%! Quantum
%R 10.22331/q10.22331/q-2018-05-24-66
%0 Journal Article
%J PHYSICAL REVIEW A
%D 2017
%T Enhancement of low-temperature thermometry by strong coupling
%A Correa, Luis A.
%A Perarnau-Llobet, Marti
%A Hovhannisyan, Karen V.
%A Hernandez-Santana, Senaida
%A Mehboudi, Mohammad
%A Sanpera, Anna
%X 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.
%B PHYSICAL REVIEW A
%V 96
%R 10.1103/PhysRevA.96.062103
%0 Journal Article
%J NEW JOURNAL OF PHYSICS
%D 2017
%T Global and local thermometry schemes in coupled quantum systems
%A Campbell, Steve
%A Mehboudi, Mohammad
%A De Chiara, Gabriele
%A Paternostro, Mauro
%X We study the ultimate bounds on the estimation of temperature for an interacting quantum system. We consider two coupled bosonic modes that are assumed to be thermal and using quantum estimation theory establish the role the Hamiltonian parameters play in thermometry. We show that in the case of a conserved particle number the interaction between the modes leads to a decrease in the overall sensitivity to temperature, while interestingly, if particle exchange is allowed with the thermal bath the converse is true. We explain this dichotomy by examining the energy spectra. Finally, we devise experimentally implementable thermometry schemes that rely only on locally accessible information from the total system, showing that almost Heisenberg limited precision can still be achieved, and we address the (im)possibility for multiparameter estimation in the system.
%B NEW JOURNAL OF PHYSICS
%V 19
%8 oct
%R 10.1088/1367-2630/aa7fac
%0 Journal Article
%J Physical Review A
%D 2016
%T Achieving sub-shot-noise sensing at finite temperatures
%A Mehboudi, Mohammad
%A Correa, Luis A.
%A Sanpera, Anna
%B Physical Review A
%V 94
%8 10/2016
%N 4
%! Phys. Rev. A
%R 10.1103/PhysRevA.94.042121
%0 Journal Article
%J Entropy
%D 2016
%T Testing a Quantum Heat Pump with a Two-Level Spin
%A Correa, Luis
%A Mehboudi, Mohammad
%B Entropy
%V 18
%P 141
%8 4/2016
%U http://www.mdpi.com/1099-4300/18/4/141/htm
%N 4
%! Entropy
%R 10.3390/e18040141
%0 Journal Article
%J Physical Review Letters
%D 2015
%T Individual Quantum Probes for Optimal Thermometry
%A Correa, Luis A.
%A Mehboudi, Mohammad
%A Adesso, Gerardo
%A Sanpera, Anna
%B Physical Review Letters
%V 114
%8 6/2015
%N 22
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.114.220405