Bidirectional conversion of electrical and optical signals lies at the foundation of the global internet. Such converters are employed at repeater stations to extend the reach of long-haul fiber optic communication systems and within data centers to exchange high-speed optical signals between computers. Likewise, coherent microwave-to-optical conversion of single photons would enable the exchange of quantum states between remotely connected superconducting quantum processors, a promising quantum computing hardware platform. Despite the prospects of quantum networking, maintaining the fragile quantum state in such a conversion process with superconducting qubits has remained elusive. Here we demonstrate the conversion of a microwave-frequency excitation of a superconducting transmon qubit into an optical photon. We achieve this using an intermediary nanomechanical resonator which converts the electrical excitation of the qubit into a single phonon by means of a piezoelectric interaction, and subsequently converts the phonon to an optical photon via radiation pressure. We demonstrate optical photon generation from the qubit with a signal-to-noise greater than unity by recording quantum Rabi oscillations of the qubit through single-photon detection of the emitted light over an optical fiber. With proposed improvements in the device and external measurement set-up, such quantum transducers may lead to practical devices capable of realizing new hybrid quantum networks, and ultimately, distributed quantum computers.

中文翻译：

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超导量子比特到光子转导

电信号和光信号的双向转换是全球互联网的基础。此类转换器用于中继站以扩展长途光纤通信系统的覆盖范围，并在数据中心内用于在计算机之间交换高速光信号。同样，单光子的相干微波到光学转换将使远程连接的超导量子处理器之间的量子状态交换成为可能，这是一个很有前途的量子计算硬件平台。尽管量子网络前景广阔，但在这种使用超导量子位的转换过程中保持脆弱的量子状态仍然难以实现。在这里，我们展示了将超导 transmon 量子位的微波频率激发转换为光学光子。我们使用中间纳米机械谐振器实现了这一点，该谐振器通过压电相互作用将量子位的电激发转换为单个声子，然后通过辐射压力将声子转换为光学光子。我们通过对光纤发射光的单光子检测来记录量子位的量子 Rabi 振荡，从而证明了从量子位产生光学光子，其信噪比大于 1。随着设备和外部测量设置的改进，这种量子传感器可能会导致实用的设备能够实现新的混合量子网络，并最终实现分布式量子计算机。然后通过辐射压力将声子转换为光学光子。我们通过对光纤发射光的单光子检测来记录量子位的量子 Rabi 振荡，从而证明了从量子位产生光学光子，其信噪比大于 1。随着设备和外部测量设置的改进，这种量子传感器可能会导致实用的设备能够实现新的混合量子网络，并最终实现分布式量子计算机。然后通过辐射压力将声子转换为光学光子。我们通过对光纤发射光的单光子检测来记录量子位的量子 Rabi 振荡，从而证明了从量子位产生光学光子，其信噪比大于 1。随着设备和外部测量设置的改进，这种量子传感器可能会导致实用的设备能够实现新的混合量子网络，并最终实现分布式量子计算机。