The Second Laws for an Information driven Current through a Spin Valve

TL;DR

This paper introduces a physically realizable Maxwell's demon using a spin valve interacting with electrons on a quantum dot tape, providing exact solutions and exploring second law inequalities in feedback control.

Contribution

It presents a new spin valve-based Maxwell's demon model, exactly solvable, and compares second law bounds in measurement-based feedback versus tape-based scenarios.

Findings

Model is exactly solvable and thermodynamically equivalent to previous models.

Second law bounds vary depending on feedback scheme and tape interactions.

Derived an effective master equation with consistent entropy production rate.

Abstract

We propose a physically realizable Maxwell's demon device using a spin valve interacting unitarily for a short time with electrons placed on a tape of quantum dots, which is thermodynamically equivalent to the device introduced by Mandal and Jarzynski [PNAS 109, 11641 (2012)]. The model is exactly solvable and we show that it can be equivalently interpreted as a Brownian ratchet demon. We then consider a measurement based discrete feedback scheme, which produces identical system dynamics, but possesses a different second law inequality. We show that the second law for discrete feedback control can provide a smaller, equal or larger bound on the maximum extractable work as compared to the second law involving the tape of bits. Finally, we derive an effective master equation governing the system evolution for Poisson distributed bits on the tape (or measurement times respectively) and we show that its associated entropy production rate contains the same physical statement as the second law involving the tape of bits.