Steady state entanglement beyond thermal limits
Francesco Tacchino
University of Pavia
Francesco Tacchino received his B.Sc. in Physics (2014) and his M.Sc. in Physical Sciences (2016) from the University of Pavia, Italy, and he is currently graduate student at the same university, where he works on quantum science and condensed matter physics.His research focuses on quantum optics, open quantum systems theory and phenomenology, quantum computing and quantum simulations, with particular attention to superconducting and hybrid platforms and to nearterm applications. He is interested in expanding the connections between fundamental physics and technology, by developing models of cavity and circuit QED devices and investigating the quantum thermodynamics of drivendissipative systems.
Abstract
Classical engines turn thermal resources into work, which is maximized for reversible operations. The quantum realm has expanded the range of useful operations beyond energy conversion, and incoherent resources beyond thermal... [ view full abstract ]
Classical engines turn thermal resources into work, which is maximized for reversible operations. The quantum realm has expanded the range of useful operations beyond energy conversion, and incoherent resources beyond thermal reservoirs. This is for example the case of entanglement generation in a drivendissipative protocol, which we analyze here as a continuous quantum machine.
Entanglement is a valuable resource in many quantum information and quantum computation protocols. In this work, we propose and describe from a theoretical perspective a device which is able to generate a significant amount of steady state entanglement without the need for a coherent driving field, thus proving that entanglement creation could be practically implemented relying only on disordered energy sources (i.e. incoherent pumps). Making use of the theory of open quantum systems and statistical mechanics we provide a description of the structure and behaviour of the proposed setup in terms of effective temperatures and effective thermal baths, thus revealing explicitly its possible interpretation as a nanoscale thermal machine.
We show that for such machine, the more irreversible the process the larger the concurrence (i.e. bipartite entanglement) in the steady state. Maximal concurrence and entropy production are reached for the hot reservoir being at negative effective temperature, beating the limits set by classic thermal operations on an equivalent system. Irreversibility is quantified by the steady state entropy production rate, a concept derived from the field of stochastic thermodynamics and extended to a quantum case in which effective temperatures are involved.
A practical implementation is discussed in a quantum optical model of a pair of incoherently driven noninteracting qubits resonantly coupled to a quantized and strongly dissipative cavity mode. Special attention is paid to realistic parameters in view of realizations and experimental tests in solid state and cavity QED systems, such as semiconductor quantum dots in photonic crystal cavities and circuit QED with superconducting resonators.
References:
[1] F. Tacchino, A. Auffèves, M.F. Santos and D. Gerace, Physical Review Letters 120, 063604 (2018).
Authors

Francesco Tacchino
(University of Pavia)

Alexia Auffèves
(Institut Néel  CNRS)

Marcelo F. Santos
(Instituto de Física, Universidade Federal do Rio de Janeiro)

Dario Gerace
(University of Pavia, Department of Physics)
Topic Areas
Fundamental science for quantum technologies , Quantum optics and nonclassical light sources
Session
OS2aR235A » Fundamental quantum optics and nonclassical light sources (14:30  Thursday, 6th September, Room 235A)
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