复合脉冲控制阶梯型多态量子系统的转移通道

Population Transfer Manipulated by Composite Pulse Sequences in the Ladder-Type Multi-State Quantum System

  • 摘要: 提出了利用复合脉冲在阶梯型多态量子系统中操控量子态演化和粒子数相干转移的方法.首先通过Morris-Shore变换,借助二能级传播算子描述多态量子系统的演化.然后利用增加脉冲序列数且单个脉冲的相位可控的技术,抑制额外的转移通道,实现高效率高鲁棒性的量子态操控和粒子数转移.最后通过数值模拟研究了额外通道和转移通道的拉比频率比、脉冲面积的变化、单光子失谐偏离零点等因素对转移效率的影响.结果表明:常被用于二能级量子系统的复合脉冲操控方法也可被应用于多态量子系统.通过增加脉冲序列数,可有效减小相关参数的扰动,保持高效率的粒子数转移.多脉冲序列复合脉冲的技术可以解决偏振不纯、激光频率不纯、控制参数扰动等造成的量子态操控效率降低等问题.研究结果对构造量子门、量子模拟等相关研究具有重要意义.

     

    Abstract: A method is proposed to achieve quantum state manipulation and population transfer in the ladder-type quantum system using composite pulse sequences. First, using the Morris-Shore transformation, the two-level propagation operator is used to describe the evolution of the multi-state quantum system. Then by increasing the number of pulse sequences with well-defined relative phase, quantum state manipulation and population transfer with high efficiency and high robustness are realized while the unwanted transition is effectively suppressed. After that, the influence of Rabi frequency ratio, the change of pulse area, and the single photon detuning on the population transfer efficiency is studied with numerical calculation. It is proved that the complex pulse manipulation method used in two-level quantum systems can also be applied to multi-state quantum systems and the parameter perturbations can be compensated automatically. This technology of composite pulse sequences can be used to overcome the efficiency reduction in the quantum manipulation process caused by polarization impurity, laser frequency deviation and parameter disturbance. This method is of great significance to the quantum gate construction and quantum simulation.

     

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