Long Junling, Ku H S, Wu Xian, Gu Xiu, Lake Russell E, Bal Mustafa, Liu Yu-Xi, Pappas David P
National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
Department of Physics, University of Colorado, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2018 Feb 23;120(8):083602. doi: 10.1103/PhysRevLett.120.083602.
Quantum networks will enable extraordinary capabilities for communicating and processing quantum information. These networks require a reliable means of storage, retrieval, and manipulation of quantum states at the network nodes. A node receives one or more coherent inputs and sends a conditional output to the next cascaded node in the network through a quantum channel. Here, we demonstrate this basic functionality by using the quantum interference mechanism of electromagnetically induced transparency in a transmon qubit coupled to a superconducting resonator. First, we apply a microwave bias, i.e., drive, to the qubit-cavity system to prepare a Λ-type three-level system of polariton states. Second, we input two interchangeable microwave signals, i.e., a probe tone and a control tone, and observe that transmission of the probe tone is conditional upon the presence of the control tone that switches the state of the device with up to 99.73% transmission extinction. Importantly, our electromagnetically induced transparency scheme uses all dipole allowed transitions. We infer high dark state preparation fidelities of >99.39% and negative group velocities of up to -0.52±0.09 km/s based on our data.
量子网络将实现量子信息通信和处理的非凡能力。这些网络需要在网络节点处对量子态进行可靠的存储、检索和操控手段。一个节点接收一个或多个相干输入，并通过量子通道向网络中的下一个级联节点发送条件输出。在此，我们通过在与超导谐振器耦合的transmon量子比特中利用电磁诱导透明的量子干涉机制来演示这种基本功能。首先，我们向量子比特 - 腔系统施加微波偏置，即驱动，以制备极化激元态的Λ型三能级系统。其次，我们输入两个可互换的微波信号，即探测信号和控制信号，并观察到探测信号的传输取决于控制信号的存在，控制信号可将器件状态切换，传输消光高达99.73%。重要的是，我们的电磁诱导透明方案使用了所有允许的偶极跃迁。基于我们的数据，我们推断出暗态制备保真度高于99.39%，负群速度高达 -0.52±0.09 km/s。
