AI 中文总结
该研究提出通过扩展相互作用范围，利用可区分量子行走者构建高保真受控相位门，其方案可避免路由不可区分粒子所需的额外单粒子门，在实际应用中具有竞争力。
AI 中文摘要
我们研究了利用相互作用粒子在双轨编码中通过量子行走实现受控相位（CP）门的方案。此前的方案聚焦于不可区分粒子（玻色子或费米子）以实现平面波散射的幺正保真度，但实际应用需要有限大小的波包并通过单粒子门进行路由，这两个因素都会引入不可避免的保真度损失。我们表明，将相互作用范围扩展至 onsite（格点内）或近邻项之外，可提供足够的散射势控制能力，从而利用可区分粒子构建出性能匹配理想玻色子/费米子的CP门。对于有限高斯波包，我们推导了基于透射系数幅值和相位导数的门保真度解析近似式。研究发现，尽管可区分粒子散射本身的保真度略低于不可区分粒子的情况，但我们提出的整体架构避免了路由不可区分粒子所需的额外单粒子门，而后者所需的迂回门引入的保真度损失约为相互作用诱导损失的一个数量级，这使得可区分粒子方案在实际应用中具有竞争力。我们的结果确立了多邻域相互作用作为连续时间量子行走量子信息处理的工具，并为有限尺寸系统中的门保真度优化提供了定量指导。
英文摘要
We investigate the implementation of controlled-phase (CP) gates with quantum walks in a dual-rail encoding through the use of interacting particles. While previous proposals have focused on indistinguishable particles (bosons or fermions) to achieve unitary fidelity for plane-wave scattering, practical implementations require finite-size wavepackets and routing through single-particle gates, both factors that introduce unavoidable fidelity losses. We show that extending the interaction range beyond on-site or first-neighbor terms provides sufficient control over the scattering potential to engineer CP gates with distinguishable particles that match the ideal bosonic/fermionic performance. For finite Gaussian wavepackets, we derive analytical approximations for the gate fidelity in terms of the transmission coefficient's magnitude and phase derivatives. We find that while distinguishable-particle scattering alone exhibits slightly lower fidelity than the indistinguishable case, the overall architecture that we propose avoids the additional single-particle gates required for routing indistinguishable particles. The roundabout gates needed for the latter indeed introduce fidelity losses approximately one order of magnitude larger than the interaction-induced losses, making the distinguishable-particle approach competitive for practical implementations. Our results establish multi-neighbor interactions as a tool for quantum information processing with continuous-time quantum walks and provide quantitative guidelines for optimizing gate fidelities in finite-size systems.
Comments16 pages, 8 figures
