Coherent feedback control in quantum transport

TL;DR

This paper explores how coherent feedback control can optimize quantum transport in mesoscopic devices, demonstrating enhanced conductance control over simple configurations using a scattering approach.

Contribution

It introduces a scattering-based framework for coherent feedback control in quantum transport and analyzes its effectiveness in optimizing device conductance.

Findings

Feedback control outperforms series configurations in conductance optimization.

Controller dimension and decoherence significantly affect control performance.

Coherent feedback enables ideal control conditions in quantum transport systems.

Abstract

We discuss control of the quantum-transport properties of a mesoscopic device by connecting it in a coherent feedback loop with a quantum-mechanical controller. We work in a scattering approach and derive results for the combined scattering matrix of the device-controller system and determine the conditions under which the controller can exert ideal control on the output characteristics. As concrete example we consider the use of feedback to optimise the conductance of a chaotic quantum dot and investigate effects of controller dimension and decoherence. In both respects we find that the performance of the feedback geometry is well in excess of that offered by a simple series configuration.