论文标题

实施五克代码和颜色代码上的易耐故障纠缠门

Implementing Fault-tolerant Entangling Gates on the Five-qubit Code and the Color Code

论文作者

Ryan-Anderson, C., Brown, N. C., Allman, M. S., Arkin, B., Asa-Attuah, G., Baldwin, C., Berg, J., Bohnet, J. G., Braxton, S., Burdick, N., Campora, J. P., Chernoguzov, A., Esposito, J., Evans, B., Francois, D., Gaebler, J. P., Gatterman, T. M., Gerber, J., Gilmore, K., Gresh, D., Hall, A., Hankin, A., Hostetter, J., Lucchetti, D., Mayer, K., Myers, J., Neyenhuis, B., Santiago, J., Sedlacek, J., Skripka, T., Slattery, A., Stutz, R. P., Tait, J., Tobey, R., Vittorini, G., Walker, J., Hayes, D.

论文摘要

我们比较了逻辑量子位上易于故障的纠缠门的两个不同的实现。在一个实例中,使用十二个Qubit-ion量子计算机在两个五个Qubit代码之间实现非转交逻辑CNOT门。用不同程度的容错评估该操作,通过包括量子误差校正电路原始素(称为标记和零散的容错)提供。在第二个实例中,使用二十个Qubit-ion量子计算机在两个[[7,1,3]]颜色代码上实现横向逻辑CNOT门。这两个代码均在不同但相似的设备上实现,并且在这两种情况下,使用与量子处理器紧密集成的经典计算环境,在运行时实现了所有量子误差校正原始原则,包括通过解码确定校正。对于原语的不同组合,将门应用到不同输入状态后,进行逻辑状态保真度测量,从而提供了过程保真度的界限。我们发现颜色代码的最高保真度操作,易于故障的垃圾邮件操作可实现0.99939(15)和0.99959(13)的保真度,并在准备逻辑X和Z运算符的特征状态时,该固定型高于平均物理Qubbit垃圾邮件的特征性垃圾邮件的平均水平垃圾邮件的平均垃圾邮件范围高于0.9968(2)和0.999970(1)和1)(and and and)。当与逻辑横向CNOT门结合使用时,我们会发现以[0.9957,0.9963]界定的平均忠诚度来执行序列 - 态制备,CNOT,测量。逻辑忠诚度范围高于类似的物理水平忠诚度界限,我们发现它是[0.9850,0.9903],反映了多个物理噪声源,例如两个Qubits的垃圾邮件误差,几个单qubit Gates,几个单Qubit Gates,一个单Qubit Gate,一个两分Qubit Gate和一些存储器误差。

We compare two different implementations of fault-tolerant entangling gates on logical qubits. In one instance, a twelve-qubit trapped-ion quantum computer is used to implement a non-transversal logical CNOT gate between two five qubit codes. The operation is evaluated with varying degrees of fault tolerance, which are provided by including quantum error correction circuit primitives known as flagging and pieceable fault tolerance. In the second instance, a twenty-qubit trapped-ion quantum computer is used to implement a transversal logical CNOT gate on two [[7,1,3]] color codes. The two codes were implemented on different but similar devices, and in both instances, all of the quantum error correction primitives, including the determination of corrections via decoding, are implemented during runtime using a classical compute environment that is tightly integrated with the quantum processor. For different combinations of the primitives, logical state fidelity measurements are made after applying the gate to different input states, providing bounds on the process fidelity. We find the highest fidelity operations with the color code, with the fault-tolerant SPAM operation achieving fidelities of 0.99939(15) and 0.99959(13) when preparing eigenstates of the logical X and Z operators, which is higher than the average physical qubit SPAM fidelities of 0.9968(2) and 0.9970(1) for the physical X and Z bases, respectively. When combined with a logical transversal CNOT gate, we find the color code to perform the sequence--state preparation, CNOT, measure out--with an average fidelity bounded by [0.9957,0.9963]. The logical fidelity bounds are higher than the analogous physical-level fidelity bounds, which we find to be [0.9850,0.9903], reflecting multiple physical noise sources such as SPAM errors for two qubits, several single-qubit gates, a two-qubit gate and some amount of memory error.

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