Stabilizing remote entanglement via waveguide dissipation

TL;DR

This paper demonstrates a method for autonomously stabilizing remote entanglement between superconducting qubits using waveguide dissipation, achieving a Bell state with high concurrence and potential for scalable quantum networks.

Contribution

It introduces a novel dissipative stabilization technique for remote entanglement via an open waveguide, enabling steady-state Bell states in superconducting qubits.

Findings

Achieved a concurrence of approximately 0.5 in stabilized entanglement.

Stabilization time constant measured at around 56 ns.

Identified system imperfections and pathways for fidelity improvement.

Abstract

Distributing entanglement between remote sites is integral to quantum networks. Here, we demonstrate the autonomous stabilization of remote entanglement between a pair of non-interacting superconducting qubits connected by an open waveguide on a chip. In this setting, the interplay between a classical continuous drive - supplied through the waveguide - and dissipation into the waveguide stabilizes the qubit pair in a dark state, which, asymptotically, takes the form of a Bell state. We use field-quadrature measurements of the photons emitted to the waveguide to perform quantum state tomography on the stabilized states, where we find a concurrence of $0.504^{+0.007}_{-0.029}$ in the optimal setting with a stabilization time constant of 56 $\pm$ 4 ns. We examine the imperfections within our system and discuss avenues for enhancing fidelities and achieving scalability in future work. The decoherence-protected, steady-state remote entanglement offered via dissipative stabilization may find applications in distributed quantum computing, sensing, and communication.