Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang, People's Republic of China.
J Phys Condens Matter. 2011 Jun 8;23(22):225702. doi: 10.1088/0953-8984/23/22/225702. Epub 2011 May 19.
We present a method for implementing an n-qubit controlled-rotation gate with three-level superconducting qubit systems in cavity quantum electrodynamics. The two logical states of a qubit are represented by the two lowest levels of each system while a higher energy level is used for the gate implementation. The method operates essentially by preparing a W state conditioned on the states of the control qubits, creating a single photon in the cavity mode, and then performing an arbitrary rotation on the states of the target qubit with the assistance of the cavity photon. It is interesting to note that the basic operational steps for implementing the proposed gate do not increase with the number of qubits n, and the gate operation time decreases as the number of qubits increases. This proposal is quite general, and can be applied to various types of superconducting devices in a cavity or coupled to a resonator.
我们提出了一种在腔量子电动力学中使用三能级超导量子比特系统实现 n 量子比特受控旋转门的方法。量子比特的两个逻辑态由每个系统的两个最低能级表示，而较高能级用于门的实现。该方法的基本操作是通过准备一个条件态 W 来实现，条件是控制量子比特的状态，在腔模式中产生一个单光子，然后在腔光子的辅助下对目标量子比特的状态进行任意旋转。有趣的是，实现所提出的门的基本操作步骤不随量子比特数 n 的增加而增加，并且门操作时间随着量子比特数的增加而减少。这个方案是相当通用的，可以应用于腔中的各种类型的超导器件或与谐振器耦合的超导器件。
