Seminar – 12th March 2015

Michele Campsi.

Scuola Normale Superiore

THURSDAY 12/3 14hs

Quantum heat engines. Microscopic theory, illustrative example and solid state implementation. 

At the very foundation of the theory of thermodynamics lies the observed fact that no machine can beat the efficiency of a Carnot engine. We address the question of what is the microscopic origin of this observed macroscopic fact. This is not a only a fundamental question but also a very practical one: Understanding the operation of thermal machines at the microscopic scale can help us design efficient and powerful nano heat engines. We shall see how the Carnot bound follows as a consequence of the fluctuation theorem which in turn is a manifestation of microscopic reversibility. To get insight into the microscopic mechanisms underlying the operation of quantum heat engines we study a device composed of two qubits, each coupled to a thermal bath, and subject to a SWAP quantum gate. We discuss its implementation with superconducting qubits and calorimetric measurements of heat exchange. Quite remarkably, the power output of this engine can be increased without compromising its efficiency.

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