任意相位CZ门及跨空间分离超导节点间的远程读取

中文摘要 AI 辅助

建立跨空间分离量子节点的完备门集是分布式量子计算和通信网络的基础。实现这一目标的方法之一是采用超导器件作为通用量子节点，能够存储和处理量子信息，并以行进的微波光子作为通信手段。在本工作中，我们在一个由两个稀释制冷机A和B组成的原始两节点超导电路QED网络中实现了纠缠门，这两个制冷机通过一条30米长的低温量子链路连接。我们执行了双向光子传输协议，其中由A处的通信量子比特发射的微波光子根据B处量子比特的状态获得条件相位。我们改变通信光子频率，从而调谐在远程节点反射期间获得的条件相位，有效实现了任意相位CZ门。我们利用这一纠缠操作从A节点对B节点中的量子比特进行单发读取。我们方案的一个有趣特点是它不需要主动节点与远程节点的精确同步；特别是，远程读取可以在远程节点不进行任何主动参与的情况下执行。这些协议为超导电路的量子通信工具箱增添了内容，并提供了一种实现基本分布式量子计算操作的方法。

英文摘要

Establishing a complete set of gates across spatially separated quantum nodes is fundamental for distributed quantum computation and communication networks. One of the approaches to do so consists of employing a superconducting device as a universal quantum node that is capable of storing and processing quantum information, and traveling microwave photons as means of communication. In this work, we realize an entangling gate across a primitive two-node superconducting circuit QED network consisting of two dilution cryostats, A and B, connected via a 30-m-long cryogenic quantum link. We perform a bidirectional photon transfer protocol, where a microwave photon emitted by the communication qubit at A acquires a conditional phase based on the state of qubit B. We vary the communication photon frequency, hence tuning the conditional phase acquired during the reflection off the remote node, effectively implementing an arbitrary-phase CZ gate. We use this entangling operation to perform single-shot readout of the qubit in node B from node A. An interesting feature of our scheme is that it does not require precise synchronization of the active node with the remote node; in particular, remote readout can be performed without any active participation by the remote node. These protocols add to the quantum communication toolbox with superconducting circuits and provide a way of realizing basic distributed quantum computing operations.

发表机构

• ETH Zurich（苏黎世联邦理工学院）
• Quantum Center, ETH Zurich（苏黎世联邦理工学院量子中心）

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