Abstract

The conventional technique for controlling the states of individual qubits and quantum registers is based on the use of high-frequency modulated pulses whose carrier frequency is close to the transition frequency between the ground states of “artificial atoms” and “molecules” (the Rabi technique). In this paper, an alternative concept for controlling superconducting qubits is developed that is based on the idea of fast excitation of a quantum system by solitary unmodulated pulses. The formation of entangled Bell states in a two-qubit superconducting register under the action of field pulses obtained by rapid single flux quantum (RSFQ) devices is demonstrated by numerical simulation. The tomography of quantum states is performed by solving the density matrix equation. It is shown that the technique of “unipolar pulses” allows one to speed up the formation of entangled states (at picosecond times) with a fidelity of 95–98%. The execution of the basic quantum algorithms is demonstrated: the Deutsch–Jozsa algorithm with an accuracy of more than 98% and Grover’s algorithm with an accuracy of 93%.

中文翻译：

---

量子位的层析成像和单极脉冲的量子算法实现

摘要

控制单个量子位和量子寄存器状态的常规技术是基于使用高频调制脉冲，其载波频率接近“人造原子”和“分子”的基态之间的跃迁频率（Rabi技术）。在本文中，基于孤立的未调制脉冲快速激发量子系统的思想，提出了一种控制超导量子位的替代概念。通过数值模拟证明了在快速单通量量子（RSFQ）装置获得的场脉冲作用下，在两个量子位超导寄存器中纠缠的贝尔状态的形成。量子态的层析成像是通过求解密度矩阵方程来进行的。结果表明，“单极脉冲”技术可以使纠缠态的形成速度（皮秒级）达到95-98％。演示了基本量子算法的执行：Deutsch-Jozsa算法的精度超过98％，Grover算法的精度为93％。