Experimental recovery of a qubit from partial collapse

TL;DR

This paper presents a method to recover a qubit after partial collapse, outperforming traditional projection techniques, demonstrated with a high-fidelity trapped ion system.

Contribution

The authors introduce a novel quantum recovery method inspired by Hahn spin-echo that works on a broader class of relaxation processes and is heralded for success.

Findings

Successful qubit recovery surpassing projection and post-selection methods

Implementation with a high-fidelity trapped ion system

Demonstration of recovery in a novel qubit setup

Abstract

We describe and implement a method to restore the state of a single qubit, in principle perfectly, after it has partially collapsed. The method resembles the classical Hahn spin-echo, but works on a wider class of relaxation processes, in which the quantum state partially leaves the computational Hilbert space. It is not guaranteed to work every time, but successful outcomes are heralded. We demonstrate using a single trapped ion better performance from this recovery method than can be obtained employing projection and post-selection alone. The demonstration features a novel qubit implementation that permits both partial collapse and coherent manipulations with high fidelity.