Ristè D, Poletto S, Huang M-Z, Bruno A, Vesterinen V, Saira O-P, DiCarlo L
QuTech and Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands.
Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands.
Nat Commun. 2015 Apr 29;6:6983. doi: 10.1038/ncomms7983.
Quantum data are susceptible to decoherence induced by the environment and to errors in the hardware processing it. A future fault-tolerant quantum computer will use quantum error correction to actively protect against both. In the smallest error correction codes, the information in one logical qubit is encoded in a two-dimensional subspace of a larger Hilbert space of multiple physical qubits. For each code, a set of non-demolition multi-qubit measurements, termed stabilizers, can discretize and signal physical qubit errors without collapsing the encoded information. Here using a five-qubit superconducting processor, we realize the two parity measurements comprising the stabilizers of the three-qubit repetition code protecting one logical qubit from physical bit-flip errors. While increased physical qubit coherence times and shorter quantum error correction blocks are required to actively safeguard the quantum information, this demonstration is a critical step towards larger codes based on multiple parity measurements.
量子数据易受环境引起的退相干以及处理它的硬件中的错误影响。未来的容错量子计算机将使用量子纠错来积极防范这两者。在最小的纠错码中，一个逻辑量子比特中的信息被编码在多个物理量子比特的更大希尔伯特空间的二维子空间中。对于每个码，一组称为稳定器的非破坏性多量子比特测量可以离散化并标记物理量子比特错误，而不会破坏编码信息。在这里，我们使用一个五量子比特超导处理器，实现了两个奇偶校验测量，它们构成了三量子比特重复码的稳定器，可保护一个逻辑量子比特免受物理比特翻转错误的影响。虽然需要增加物理量子比特的相干时间并缩短量子纠错块来积极保护量子信息，但这一演示是迈向基于多个奇偶校验测量的更大码的关键一步。
