Distributed Quantum Computing across an Optical Network Link

TL;DR

This paper demonstrates a scalable distributed quantum computing architecture using photonic networks to connect trapped-ion modules, successfully teleporting quantum gates and executing a distributed Grover's algorithm with high fidelity.

Contribution

First experimental demonstration of deterministic remote entanglement and quantum gate teleportation enabling distributed quantum algorithms across separated modules.

Findings

Achieved 86% fidelity in teleporting a controlled-Z gate.

Successfully implemented Grover's search algorithm with 71% success rate.

Demonstrated distributed iSWAP and SWAP circuits with multiple quantum gate teleportations.

Abstract

Distributed quantum computing (DQC) combines the computing power of multiple networked quantum processing modules, enabling the execution of large quantum circuits without compromising on performance and connectivity. Photonic networks are well-suited as a versatile and reconfigurable interconnect layer for DQC; remote entanglement shared between matter qubits across the network enables all-to-all logical connectivity via quantum gate teleportation (QGT). For a scalable DQC architecture, the QGT implementation must be deterministic and repeatable; until now, there has been no demonstration satisfying these requirements. We experimentally demonstrate the distribution of quantum computations between two photonically interconnected trapped-ion modules. The modules are separated by $\sim$ 2 m, and each contains dedicated network and circuit qubits. By using heralded remote entanglement between the network qubits, we deterministically teleport a controlled-Z gate between two circuit qubits in separate modules, achieving 86% fidelity. We then execute Grover's search algorithm - the first implementation of a distributed quantum algorithm comprising multiple non-local two-qubit gates - and measure a 71% success rate. Furthermore, we implement distributed iSWAP and SWAP circuits, compiled with 2 and 3 instances of QGT, respectively, demonstrating the ability to distribute arbitrary two-qubit operations. As photons can be interfaced with a variety of systems, this technique has applications extending beyond trapped-ion quantum computers, providing a viable pathway towards large-scale quantum computing for a range of physical platforms.