Fluctuation relations and Maxwell's demon in a circuit QED setup

Nathanaël Cottet, Benjamin Huard

Г. Ф. Ефремов, A. Y. Chekhov, Lev G. Mourokh +1 more

Mihai D. Vidrighin, Oscar Dahlsten, Marco Barbieri +3 more

We report an experimental realization of Maxwell's demon in a photonic setup. We show that a measurement at the few-photons level followed by a feed-forward operation allows the extraction of work from intense thermal light into an electric circuit. The interpretation of the experiment stimulates the derivation of an equality relating work extraction to information acquired by measurement. We derive a bound using this relation and show that it is in agreement with the experimental results. Our work puts forward photonic systems as a platform for experiments related to information in thermodynamics.

Abraham J. Letter

A companion programme derives an uncertainty floor, no-signalling, and the Clausius relation from one clause: all access is mediated by fresh cells of a finite, passive (KMS) sector. Whatever its fundamental status, that clause makes five sharp, testable claims about a laboratory system with the same architecture — a long-lived oscillator accessed only through a stream of ancilla qubits. We propose a circuit-QED realisation and specify all five with quantitative targets, from a coupling-independent estimation floor to a Bell frontier reaching 2√2 at zero demon work. Requirements sit within demonstrated capability. Keywords: circuit QED, collision models, quantum thermodynamics, Maxwell's demon, uncertainty relations, Bell inequalities, open quantum systems, experimental proposal, quant-ph

Matthew Reed, Lev S. Bishop, L. DiCarlo +7 more

Xingrui Song, Mahdi Naghiloo, Kater W. Murch

While quantum measurement theories are built around density matrices and observables, the laws of thermodynamics are based on processes such as the ones used in heat engines and refrigerators. The study of quantum thermodynamics fuses these two distinct paradigms. In this article, we highlight the usage of quantum process matrices as a unified language for describing thermodynamic processes in the quantum regime. We experimentally demonstrate this in the context of a quantum Maxwell demon, where two major quantities are commonly investigated: the average work extraction $\ensuremath{\langle}W\ensuremath{\rangle}$ and the efficacy $\ensuremath{\gamma}$, which measures how efficiently the feedback operation uses the obtained information. Using the tool of quantum process matrices, we develop optimal feedback protocols for these two quantities and experimentally investigate them in a superconducting circuit QED setup.