To reach their full potential, quantum computers need to be resilient to noise and decoherence. In such a fault-tolerant quantum computer, errors must be corrected in real time to prevent them from propagating between components^1,2. This requirement is especially pertinent while applying quantum gates, where the interaction between components can cause errors to spread quickly throughout the system. However, the large overhead involved in most fault-tolerant architectures^2,3 makes implementing these systems a daunting task, motivating the search for hardware-efficient alternatives^4,5. Here, we present a gate enacted by an ancilla transmon on a cavity-encoded logical qubit that is fault-tolerant to ancilla decoherence and compatible with logical error correction. We maintain the purity of the encoded qubit by correcting ancilla-induced errors in real time, yielding a reduction of the logical gate error by a factor of two in the presence of naturally occurring decoherence. We also demonstrate a sixfold suppression of the gate error with increased ancilla relaxation errors and a fourfold suppression with increased ancilla dephasing errors. The results demonstrate that bosonic logical qubits can be controlled by error-prone ancilla qubits without inheriting the ancilla’s inferior performance. As such, error-corrected ancilla-enabled gates are an important step towards fault-tolerant processing of bosonic qubits.

为了发挥其全部潜能，量子计算机需要对噪声和退相干具有弹性。在这样的容错量子计算机中，必须实时纠正错误，以防止错误在组件^1,2之间传播。在应用量子门时，这一要求尤其重要，因为在量子门中，组件之间的相互作用会导致错误迅速扩散到整个系统中。但是，大多数容错体系结构^2,3中涉及的大量开销使实现这些系统成为一项艰巨的任务，从而促使人们寻求硬件效率更高的替代方案^4,5。在这里，我们介绍了一个由门童transmon在模腔编码的逻辑量子位上制定的门，该位容错对门廊的退相干具有容错性，并且与逻辑纠错兼容。我们通过实时校正ancilla引起的错误来保持编码量子位的纯度，在自然发生退相干的情况下，逻辑门错误减少了两倍。我们还证明了增加门禁弛豫误差对门控误差的六倍抑制和增加了门坎移相误差对门限的四倍抑制。结果表明，易于出错的辅助量子位可以控制玻色逻辑量子位，而不会继承辅助性能的劣等性能。因此，经过错误校正的辅助子通道门是朝容错处理玻色子qubits迈出的重要一步。