Reducing intrinsic decoherence in a superconducting circuit by quantum error detection

TL;DR

This paper demonstrates a quantum error detection protocol using quantum un-collapsing in a superconducting circuit, significantly extending quantum state lifetime by rejecting energy relaxation errors.

Contribution

It introduces the first experimental implementation of an algorithm-based quantum error detection protocol to improve qubit coherence times.

Findings

Quantum error detection suppresses energy relaxation in superconducting qubits.

The protocol extends quantum state storage time by approximately three times.

Error rejection reduces success probability but enhances state fidelity.

Abstract

A fundamental challenge for quantum information processing is reducing the impact of environmentally-induced errors. Quantum error detection (QED) provides one approach to handling such errors, in which errors are rejected when they are detected. Here we demonstrate a QED protocol based on the idea of quantum un-collapsing, using this protocol to suppress energy relaxation due to the environment in a three-qubit superconducting circuit. We encode quantum information in a target qubit, and use the other two qubits to detect and reject errors caused by energy relaxation. This protocol improves the storage time of a quantum state by a factor of roughly three, at the cost of a reduced probability of success. This constitutes the first experimental demonstration of an algorithm-based improvement in the lifetime of a quantum state stored in a qubit.