论文标题
自主量子误差校正和用挤压猫盘的耐故障量子计算
Autonomous quantum error correction and fault-tolerant quantum computation with squeezed cat qubits
论文作者
论文摘要
我们建议使用挤压CAT(SC)代码(SC)代码对主要误差源,激发损失,在连续变量系统中提出一种自主量子误差校正方案。通过储层工程,我们表明结构化耗散可以稳定两个组件SC,同时自主纠正错误。这种耗散的实现仅需要三种骨气模式之间的低阶非线性耦合,或者在骨模式和QUTRIT之间。尽管我们提出的方案是独立的,但它可以通过当前的实验平台(例如超导电路和被困的离子系统)来实现。与稳定的CAT相比,稳定的SC具有较低的主要错误率和明显增强的噪声偏差。此外,SC的偏置操作的错误率要低得多。结合使用,稳定的SC在与外部离散变量代码连接时会带来更好的逻辑性能。 Surface-SC方案在损失率$κ_1$与工程耗散率$κ__2$之间的阈值比率增加了一个以上的数量级。在实用的噪声比$κ_1/κ__2= 10^{ - 3} $下,重复SC方案也可以达到$ 10^{ - 15} $逻辑错误率,即使平均平均激发次数为4,这已经足够了,这足以使实际上有用的量子算法。
We propose an autonomous quantum error correction scheme using squeezed cat (SC) code against the dominant error source, excitation loss, in continuous-variable systems. Through reservoir engineering, we show that a structured dissipation can stabilize a two-component SC while autonomously correcting the errors. The implementation of such dissipation only requires low-order nonlinear couplings among three bosonic modes or between a bosonic mode and a qutrit. While our proposed scheme is device independent, it is readily implementable with current experimental platforms such as superconducting circuits and trapped-ion systems. Compared to the stabilized cat, the stabilized SC has a much lower dominant error rate and a significantly enhanced noise bias. Furthermore, the bias-preserving operations for the SC have much lower error rates. In combination, the stabilized SC leads to substantially better logical performance when concatenating with an outer discrete-variable code. The surface-SC scheme achieves more than one order of magnitude increase in the threshold ratio between the loss rate $κ_1$ and the engineered dissipation rate $κ_2$. Under a practical noise ratio $κ_1/κ_2 = 10^{-3}$, the repetition-SC scheme can reach a $10^{-15}$ logical error rate even with a small mean excitation number of 4, which already suffices for practically useful quantum algorithms.