Deterministic photon-photon gates enable the controlled generation of entanglement between mobile carriers of quantum information. Such gates have thus far been exclusively realized in the optical domain and by relying on postselection. Here, we present a nonpostselected, deterministic, photon-photon gate in the microwave frequency range realized using superconducting circuits. We emit photonic qubits from a source chip and route those qubits to a gate chip with which we realize a universal gate set by combining controlled absorption and reemission with single-qubit gates and qubit-photon controlled-phase gates. We measure quantum process fidelities of 75% for single- and of 57% for two-qubit gates, limited mainly by radiation loss and decoherence. This universal gate set has a wide range of potential applications in superconducting quantum networks.

中文翻译：

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一种用于巡回微波光子的通用量子门集的实现

确定性光子-光子门能够在量子信息的移动载流子之间控制纠缠的产生。迄今为止，此类门仅在光域中实现，并且依赖于后选择。在这里，我们提出了使用超导电路实现的微波频率范围内的非后选、确定性光子-光子门。我们从源芯片发射光子量子位并将这些量子位路由到门芯片，通过将受控吸收和再发射与单量子位门和量子位光子控制相位门相结合，我们实现了通用门集。我们测量了单量子位门的 75% 和双量子位门的 57% 的量子过程保真度，主要受辐射损失和退相干的限制。