Autonomous Distribution of Programmable Multiqubit Entanglement in a Dual-Rail Quantum Network

TL;DR

This paper introduces a scalable, autonomous method for distributing multiqubit entangled states across quantum networks using correlated photons in a dual-rail waveguide setup, avoiding complex control.

Contribution

It presents a novel, fully autonomous scheme for preparing distributed multiqubit entanglement with adjustable degrees of entanglement in a scalable waveguide QED system.

Findings

Preparation time scales linearly with system size.

Speedup possible with larger amplifier bandwidth.

Scheme does not require precise pulse control.

Abstract

We propose and analyze a scalable and fully autonomous scheme for preparing spatially distributed multiqubit entangled states in a dual-rail waveguide QED setup. In this approach, arrays of qubits located along two separated waveguides are illuminated by correlated photons from the output of a nondegenerate parametric amplifier. These photons drive the qubits into different classes of pure entangled steady states, for which the degree of multipartite entanglement can be conveniently adjusted by the chosen pattern of local qubit-photon detunings. Numerical simulations for moderate-sized networks show that the preparation time for these complex multiqubit states increases at most linearly with the system size and that one may benefit from an additional speedup in the limit of a large amplifier bandwidth. Therefore, this scheme offers an intriguing new route for distributing ready-to-use multipartite entangled states across large quantum networks, without requiring any precise pulse control and relying on a single Gaussian entanglement source only.