Deterministic remote entanglement using a chiral quantum interconnect

TL;DR

This paper demonstrates a chiral quantum interconnect for superconducting modules that uses quantum interference and reinforcement learning to generate high-fidelity remote entanglement, enabling scalable quantum networks.

Contribution

It introduces a chiral microwave quantum interconnect with optimized photon emission and absorption, achieving high-fidelity remote entanglement between modules.

Findings

Achieved 62.4% and 62.1% fidelity in remote entanglement.

Used reinforcement learning to optimize photon absorption.

Enabled directional quantum communication between modules.

Abstract

Quantum interconnects facilitate entanglement distribution between non-local computational nodes. For superconducting processors, microwave photons are a natural means to mediate this distribution. However, many existing architectures limit node connectivity and directionality. In this work, we construct a chiral quantum interconnect between two nominally identical modules in separate microwave packages. We leverage quantum interference to emit and absorb microwave photons on demand and in a chosen direction between these modules. We optimize the protocol using model-free reinforcement learning to maximize absorption efficiency. By halting the emission process halfway through its duration, we generate remote entanglement between modules in the form of a four-qubit W state with 62.4 +/- 1.6% (leftward photon propagation) and 62.1 +/- 1.2% (rightward) fidelity, limited mainly by propagation loss. A chiral quantum network comprising many modules provides a platform for the exploration of novel many-body physics and quantum simulation. This quantum network architecture enables all-to-all connectivity between non-local processors for modular and extensible quantum computation.