On-demand maximally entangled states with a parity meter and continuous feedback

TL;DR

This paper proposes two continuous feedback schemes for parity measurements that generate on-demand maximally entangled states while avoiding dephasing, applicable across various solid-state quantum systems.

Contribution

It introduces novel feedback methods that prevent measurement-induced dephasing, enabling steady maximally entangled states in parity subspaces.

Findings

Achieved steady maximally entangled states with feedback.

Reduced measurement-induced dephasing effects.

Applicable to various solid-state quantum platforms.

Abstract

Generating on-demand maximally entangled states is one of the corner stones for quantum information processing. Parity measurements can serve to create Bell states and have been implemented via an electronic Mach-Zehnder interferometer among others. However, the entanglement generation is necessarily harmed by measurement induced dephasing processes in one of the two parity subspace. In this work, we propose two different schemes of continuous feedback for a parity measurement. They enable us to avoid both the measurement-induced dephasing process and the experimentally unavoidable dephasing, e.g. due to fluctuations of the gate voltages controlling the initialization of the qubits. We show that we can generate maximally entangled steady states in both parity subspaces. Importantly, the measurement scheme we propose is valid for implementation of parity measurements with feedback loops in various solid-state environments.