• mardi 28 novembre 2017

Séminaire Nanoélectronique Quantique : Alexey Feofanov

14h00 // Salle « Louis Neel » (C1-207)

Institut Néel
25 avenue des martyrs - Grenoble

Near-quantum-limited microwave amplification and nonreciprocal transmission using engineered mechanical dissipation
Alexey Feofanov (EPFL Lausanne)

Engineered dissipation can be used for quantum state preparation. This is achieved with a suitably engineered coupling to a dissipative cold reservoir usually formed by an electromagnetic mode. In the field of cavity electro- and optomechanics, the electromagnetic cavity naturally serves as a cold reservoir for the mechanical mode. Here, we realize the opposite scenario and engineer a mechanical oscillator cooled close to its ground state into a cold dissipative reservoir for microwave photons in a superconducting circuit. By tuning the coupling to this dissipative mechanical reservoir, we demonstrate dynamical backaction control of the microwave field, leading to stimulated emission and maser action. Moreover, the reservoir can function as a useful quantum resource, allowing the implementation of a near-quantum-limited phase-preserving microwave amplifier. We also realise reconfigurable nonreciprocal transmission between two microwave modes using purely optomechanical interactions in a superconducting electromechanical circuit and analyze the transmission as well as the noise properties of this nonreciprocal circuit. The scheme relies on the interference in two mechanical modes that mediate coupling between microwave cavities. Finally, we show how quantum-limited circulators can be realized with the same principle. The technology can be built on-chip without any external magnetic field and is hence fully compatible with superconducting quantum circuits. All-optomechanically-mediated nonreciprocity demonstrated here can also be extended to implement directional amplifiers. Such engineered mechanical dissipation extends the toolbox of quantum manipulation techniques of the microwave field and constitutes a new ingredient for optomechanical protocols.

Contact : Alexey Feofanov

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