Fast and Robust Remote Two-Qubit Gates on Distributed Qubits

TL;DR

This paper presents a fast, robust remote two-qubit gate scheme for distributed quantum computing, utilizing geometric phases and deep learning-optimized control waveforms to achieve high fidelity operations over several meters.

Contribution

It introduces a novel remote geometric gate scheme with gradient-based control optimization, demonstrating high-fidelity, rapid gates suitable for modular quantum processors.

Findings

Achieved high-fidelity SWAP and √SWAP gates within 30 ns.

Gate errors of 1.16% for SWAP and 0.91% for √SWAP after relaxation correction.

Simulation shows implementation feasibility over several meters of cable.

Abstract

Distributed quantum computing offers a potential solution to the complexity of superconducting chip hardware layouts and error correction algorithms. High-quality gates between distributed chips enable the simplification of existing error correction algorithms. This article proposes and demonstrates a remote quantum geometric gate scheme via parametric modulation. Our scheme inherits the intrinsic robustness of geometric phases. Meanwhile, by employing gradient-based optimization algorithms(Adaptive Moment Estimation) from deep learning, we design control waveforms that significantly suppress population leakage. We experimentally realize the rapid remote SWAP and $\sqrt{\text{SWAP}}$ gates with high fidelity, completing operation in about 30 ns. The gate error of SWAP ($\sqrt{\text{SWAP}}$) is 1.16\% (0.91\%) after excluding the effect of energy relaxation. The simulation demonstrate that this scheme can be implemented in the distributed chips connected by cables extending several meters. Our results highlight the effectiveness of the proposed protocol in enabling modular quantum processors, offering a promising path toward the realization of fault-tolerant quantum computation.