Charge Qubit Purification by an Electronic Feedback Loop

TL;DR

This paper introduces a feedback control scheme using a single-electron transistor to purify and stabilize pure qubit states in solid-state quantum computing, effective at various temperatures.

Contribution

It presents a novel electronic feedback method for qubit purification that is simple, robust, and effective regardless of initial states or temperature conditions.

Findings

Successful stabilization of pure delocalized qubit states

Purification achieved after few electron jumps

Independent of initial qubit state

Abstract

We propose the manipulation of an isolated qubit by a simple instantaneous closed-loop feedback scheme in which a time-dependent electronic detector current is directly back-coupled into qubit parameters. As specific detector model we employ a capacitively coupled single-electron transistor. We demonstrate the stabilization of pure delocalized qubit states above a critical detector-qubit coupling. This electronic purification is independent of the initial qubit state and is accomplished after few electron jumps through the detector. Our simple scheme can be used for the efficient and robust initialization of solid-state qubits in quantum computational algorithms at arbitrary temperatures.