AMO Seminar

Dr. Raam Uzdin, Hebrew University, Jerusalem, Israel

"Collective operation of quantum heat machines via coherence recycling, and coherence induced reversibility"

4:00pm, RLM 11.204

Abstract: Collective operations where a set of elements interact and generate effects that are beyond the reach of the individual non interacting elements, are always of great interest in physics. In this work we show how to construct collective quantum heat machines and explore their performance boosts with respect to regular machines. Quantum coherence that give rise to single particle quantum effects are used here to generate multi particle collective effects. Coherence is extracted from one engine and injected to the other. Even though this 'coherence recycling' does not involve any energy exchange and it keeps the engines unentangled with each other, it leads to an entirely different thermodynamics behavior and to performance boosts. We show that the power of the collective machine scales quadratically with the number of engines N, and not linearly as expected in individual operation. Furthermore, we quantify the reversibility of the collective machine and show that it can be N times more reversible while producing N times more power compared to N units that operate non collectively. Surprisingly, the collective machine can be more reversible than its most reversible element. This high level of reversibility becomes possible due to a fascinating symbiotic mechanism between engine pairs.