论文标题
具有离散时间量子步行的光谱磁化棘轮
Spectral Magnetization Ratchets with Discrete Time Quantum Walks
论文作者
论文摘要
我们预测并理论上研究了周期性离散时间量子步行（DTQWS）的光谱磁化的棘轮效应 - 重复了$ M $不同的DTQWS的序列。这些广义DTQW是通过在离散时间定期改变相应的硬币操作员参数来实现的。我们考虑周期$ m = 1,2,3 $。 $ M $ - 周期DTQWS的动力学以两种频段分散关系$ω^{（m）} _ {\ pm}（k）$为特征，其中$ k $是波动矢量。我们确定了$ M $ - 周期性DTQWS的广义平价对称性。通过$ M = 2,3 $，可以通过适当选择硬币操作员参数以$ M = 2,3 $打破对称性。获得的对称破坏会导致棘轮效应，即非零光谱磁化$ m_s（ω）$的外观。可以在周期性DTQW的时间相关相关函数的连续量子测量框架中观察到这种棘轮效应。
We predict and theoretically study in detail the ratchet effect for the spectral magnetization of periodic discrete time quantum walks (DTQWs) --- a repetition of a sequence of $m$ different DTQWs. These generalized DTQWs are achieved by varying the corresponding coin operator parameters periodically with discrete time. We consider periods $m=1,2,3$. The dynamics of $m$-periodic DTQWs is characterized by a two-band dispersion relation $ω^{(m)}_{\pm}(k)$, where $k$ is the wave vector. We identify a generalized parity symmetry of $m$-periodic DTQWs. The symmetry can be broken for $m=2,3$ by proper choices of the coin operator parameters. The obtained symmetry breaking results in a ratchet effect, i.e. the appearance of a nonzero spectral magnetization $M_s(ω)$. This ratchet effect can be observed in the framework of continuous quantum measurements of the time-dependent correlation function of periodic DTQWs.
