Superconducting resonators as beam splitters for linear-optics quantum computation

TL;DR

This paper demonstrates that superconducting resonators in circuit QED can serve as high-fidelity beam splitters, enabling linear-optics quantum computation with microwave photons, thus advancing quantum computing technology.

Contribution

The authors introduce high-fidelity superconducting resonators as beam splitters for microwave photons, expanding the toolkit for circuit QED-based linear optics quantum computing.

Findings

Achieved >99.92% fidelity in superconducting beam splitters.

Enabled implementation of LOQC components in microwave regime.

Demonstrated compatibility with existing superconducting qubit technologies.

Abstract

A functioning quantum computer will be a machine that builds up, in a programmable way, nonclassical correlations in a multipartite quantum system. Linear optics quantum computation (LOQC) is an approach for achieving this function that requires only simple, reliable linear optical elements, namely beam splitters and phase shifters. Nonlinear optics is only required in the form of single-photon sources for state initialization, and detectors. However, the latter remain difficult to achieve with high fidelity. A new setting for quantum optics has arisen in circuit quantum electrodynamics (cQED) using superconducting (SC) quantum devices, and opening up the way to LOQC using microwave, rather than visible photons. Much progress is being made in SC qubits and cQED: high-fidelity Fock state generation and qubit measurements provide single photon sources and detection. Here we show that the LOQC toolkit in cQED can be completed with high-fidelity (>99.92%) linear optical elements.