Stabilizing Remote Entanglement via Waveguide Dissipation
Parth S. Shah, Frank Yang, Chaitali Joshi, Mohammad Mirhosseini
Abstract
Distributing entanglement between remote sites is integral to quantum networks. Here, we demonstrate the autonomous stabilization of remote entanglement between a pair of noninteracting 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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <a:msubsup> <a:mn>0.504</a:mn> <a:mrow> <a:mo>−</a:mo> <a:mn>0.029</a:mn> </a:mrow> <a:mrow> <a:mo>+</a:mo> <a:mn>0.007</a:mn> </a:mrow> </a:msubsup> </a:math> in the optimal setting with a stabilization time constant of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <d:mn>56</d:mn> <d:mo>±</d:mo> <d:mn>4</d:mn> </d:math> 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. Published by the American Physical Society 2024