Measurement-induced entanglement of two transmon qubits by a single photon

TL;DR

This paper proposes a heralded, deterministic method for entangling two distant transmon qubits using a single photon in a Mach-Zehnder interferometer, enabling reliable distributed quantum computation.

Contribution

It introduces a novel entanglement scheme utilizing single-photon detection and strong qubit-photon coupling in superconducting circuits, achieving on-demand entanglement creation.

Findings

Single-photon detection projects qubits onto a maximally entangled state.

The protocol is heralded and robust against photon loss.

Strong qubit-photon coupling enables effective entanglement generation.

Abstract

On-demand creation of entanglement between distant qubits is a necessary ingredient for distributed quantum computation. We propose an entanglement scheme that allows for single-shot deterministic entanglement creation by detecting a single photon passing through a Mach-Zehnder interferometer with one transmon qubit in each arm. The entanglement production essentially relies on the fact that superconducting microwave structures allow to achieve strong coupling between the qubit and the photon. By detecting the photon via a photon counter, a parity measurement is implemented and the wave function of the two qubits is projected onto a maximally entangled state. Most importantly, the entanglement generation is heralded such that our protocol is not susceptible to photon loss due to the indivisible nature of single photons.