Observation of quantum jumps in a superconducting artificial atom

TL;DR

This paper reports the first observation of quantum jumps in a superconducting artificial atom, demonstrating continuous high-fidelity monitoring that advances solid state quantum information processing and potential quantum error correction.

Contribution

It introduces a method to observe quantum jumps in a superconducting qubit using ultralow-noise amplification, enabling real-time monitoring and control.

Findings

Quantum jumps observed in a superconducting qubit.

High-fidelity continuous monitoring achieved.

Potential for quantum error correction demonstrated.

Abstract

A continuously monitored quantum system prepared in an excited state will decay to its ground state with an abrupt jump. The jump occurs stochastically on a characteristic time scale T1, the lifetime of the excited state. These quantum jumps, originally envisioned by Bohr, have been observed in trapped atoms and ions, single molecules, photons, and single electrons in cyclotrons. Here we report the first observation of quantum jumps in a macroscopic quantum system, in our case a superconducting "artificial atom" or quantum bit (qubit) coupled to a superconducting microwave cavity. We use a fast, ultralow-noise parametric amplifier to amplify the microwave photons used to probe the qubit state, enabling continuous high-fidelity monitoring of the qubit. This technique represents a major step forward for solid state quantum information processing, potentially enabling quantum error correction and feedback, which are essential for building a quantum computer. Our technology can also be readily integrated into hybrid circuits involving molecular magnets, nitrogen vacancies in diamond, or semiconductor quantum dots.