[论文解读] Variational Quantum Transduction

Pengcheng Liao, Haowei Shi+1 more|arXiv (Cornell University)|Mar 4, 2026

Quantum Computing Algorithms and Architecture被引用 0

一句话总结

论文提出 Variational Quantum Transduction (VQT)，一种变分电路框架，在现实约束下优化量子传导协议，并显示其在自适应设定下可超越非自适应方案，但在高斯自适应策略上收益有限。

ABSTRACT

Quantum transducers are critical for quantum interconnect, enabling coherent signal transfer across disparate frequency domains. Beyond material and device advances, protocol design has become a powerful means to improve transduction. We introduce a variational quantum transduction (VQT) framework that employs variational tools from near-term quantum computing to systematically optimize protocol performance. As a variational quantum circuit framework, VQT is not plagued by known training issues such as barren plateau, because a small-scale problem is sufficient for substantial advantage and training only needs to be done once to configure a VQT system. Maximizing the quantum information rate within this framework yields protocols that surpass all known schemes in their respective classes. For non-adaptive protocols, VQT exceeds the performance envelopes of Gottesman-Kitaev-Preskill (GKP)-based and entanglement-assisted approaches. In the adaptive setting, VQT provides only a marginal improvement over Gaussian feedforward strategies, indicating that Gaussian adaptive transduction is already close to optimal. With increasingly universal quantum control, VQT provides a systematic path toward optimal quantum transduction.

研究动机与目标

• 将量子传导作为量子网络与感测的原语进行动机阐释。
• 开发一个变分量子电路框架以优化传导协议。
• 在统一的相干信息度量下比较非自适应与自适应传导。
• 证明 VQT 在基于 GKP 的和纠缠辅助的非自适应协议上具有更好表现，而自适应高斯策略仍然非常有效。

提出的方法

• 将传导建模为带有效率 η 的分束器相互作用，并以相干信息作为性能度量。
• 引入一个变分量子电路（VQC）框架，输入态制备器用于光信号 S 与微波输入 (P,A) 以及联合解码器。
• 在分层 VQC 架构中使用回声条件位移（ECD）门作为硬件本地原语。
• 包含一个可选的自适应模块以执行基于测量的前馈，从而实现自适应传导。
• 在能量与资源约束下优化输入态和解码操作，以最大化相干信息。
• 将 VQT 与基线协议进行比较：带有两模压缩的锚态纠缠辅助（EA）方案、GKP 环境辅助方案，以及自适应高斯传导。

实验结果

研究问题

• RQ1 在固定能量与资源约束下，VQT 能否识别最大化相干信息的传导协议？
• RQ2 在 VQT 优化下，非自适应与自适应传导协议有何比较？
• RQ3 在非自适应传导中，非高斯性与纠缠在不同透射率区间起到怎样的作用？
• RQ4 一旦有前馈，高斯自适应传导是否接近最优？
• RQ5 VQT 优化输入态随透射率 η 的演化如何（低 η 时类似于 GKP，高 η 时呈现高斯特征）？

主要发现

• Fully variational entanglement-assisted non-adaptive transduction yields the highest coherent information across η.
• Optimal non-adaptive inputs transition from GKP-like at low η to Gaussian as η increases, with entanglement mainly helpful at higher η.
• Adaptive VQT provides only a modest improvement over Gaussian adaptive strategies, indicating Gaussian adaptivity is near-optimal.
• In adaptive settings, the optimized inputs become squeezed-thermal in S and squeezed-vacuum in P, with no detectable entanglement or non-Gaussianity in PA.
• VQT without EA approaches the QT channel capacity for η > ~0.6, showing limited added value from ancilla in high-transmissivity regimes.
• Overall, VQT outperforms baseline non-adaptive protocols and offers a systematic path toward optimal quantum transduction.