Reverse quantum state engineering using electronic feedback loops

TL;DR

This paper introduces an all-electronic feedback technique to control quantum states, enabling stabilization and entanglement creation in charge qubits through a novel inverse eigenvalue problem approach.

Contribution

It presents a new quantum feedback scheme using single-electron transistors to stabilize pure states and entanglement, with detailed applications to charge qubits.

Findings

Successfully stabilizes delocalized pure states in charge qubits.

Achieves stabilization of maximally entangled Bell states.

Provides a general framework linking feedback control to inverse eigenvalue problems.

Abstract

We propose an all-electronic technique to manipulate and control interacting quantum systems by unitary single-jump feedback conditioned on the outcome of a capacitively coupled electrometer and in particular a single-electron transistor. We provide a general scheme to stabilize pure states in the quantum system and employ an effective Hamiltonian method for the quantum master equation to elaborate on the nature of stabilizable states and the conditions under which state purification can be achieved. The state engineering within the quantum feedback scheme is shown to be linked with the solution of an inverse eigenvalue problem. Two applications of the feedback scheme are presented in detail: (i) stabilization of delocalized pure states in a single charge qubit and (ii) entanglement stabilization in two coupled charge qubits. In the latter example we demonstrate the stabilization of a maximally entangled Bell state for certain detector positions and local feedback operations.