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Sujet de stage / Master 2 Internship

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Quantum thermal engine with a voltage biased Josephson junction

Contact: PORTIER Fabien, , fabien.portier@cea.fr, +33 1 69 08 72 16/74 75
We will develop a quantum thermal engine based on a dc voltage biased Josephson junction coupled to two microwave resonators, a hot, high frequency one and a cold, low frequency one. High frequency photons are then absorbed and low frequency one emitted, the energy difference being converted into electrostatic energy.
Possibility of continuation in PhD: Oui
Deadline for application:06/04/2018

Full description:
This project belongs to the fast growing field of quantum thermodynamics. We wish to develop a simple thermal engine whose operating principle is intrinsically quantum. The device involved in this project is the following: a Josephson junction is coupled to two resonators of frequency ν1,ν2 with ν1>ν2 and biased at a voltage V. As the Josephson junction is a non-dissipative element, a DC current can flow through the circuit only if the energy 2eV =n1 hν1+ n2 hν2 provided by the generator upon the transfer of a Cooper pair is converted into electromagnetic excitations of the resonators. We have recently detected the radiation emitted at 2eV = hν1+ hν2, the transfer of a Cooper pair then being associated to the emission of a photon in both resonators. We have shown that the resulting radiation is non classical [1]. The purpose of this internship is to demonstrate that this device can be used as a thermal engine: When the two modes are at held at different temperatures, with T1>T2 , chosen so that there are more photons in 1 than in 2. Then if biasing the junction at 2eV = hν1- hν2, one expects a backflow of Cooper pairs, associated to the absorption of a photons at frequency ν1 and re-emission of photons at ν2., resulting in the conversion of heat into electrical work. Unlike most classical machines, the efficiency of this engine is predicted to be high, even at maximum power[2]. The sample being already available, the trainee will perform the experiment, cool the sample with a dilution refrigerator, ensure different populations of the two modes and measure the induced current by ultra low-noise measurements. All these techniques are well mastered by our group.

1 M. Westig et al., Phys Rev Lett 119, 137001 (2017)
2 P. P. Hofer, J.-R. Souquet, and A. A. Clerk, Phys. Rev. B 93, 041418 (2016)

Technics/methods used during the internship:
Nanofabrication, cryogenics, ultralow noise electronics

Tutor of the internship


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