Stabilizing remote entanglement via waveguide dissipation

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.