# Coherent control in quantum transport: amplification, filtering and switching at finite bias

## TL;DR

This paper investigates how simple coherent feedback controllers can enhance quantum transport properties like amplification, filtering, and switching under finite bias conditions, revealing key voltage scales for effective control.

## Contribution

It demonstrates that single-parameter controllers can improve quantum transport functionalities and analyzes the impact of finite bias on these effects.

## Key findings

- Controllers enable amplification and filtering in quantum transport.
- Finite bias affects the effectiveness of feedback control.
- Identifies voltage scales critical for maintaining control functionalities.

## Abstract

We consider coherent feedback control of quantum transport and focus on the application of simple controllers and the effects of a finite bias voltage. We show that simple single-parameter controllers can give rise to a range of useful effects such as amplification of changes in plant transmission, increased resolution of energy filtration, and the detection of differences between otherwise indistinguishable plants. We explore how these effects are impacted by the phase-averaging effects associated with the application of a finite bias and identify important voltage scales for the maintenance of the functionalities achieved through feedback control.