论文标题
耗散量子的时间最佳控制
Time-optimal control of a dissipative qubit
论文作者
论文摘要
使用基于Pontryagin的最大原理的形式主义来确定由具有有限控制的Hamiltonian将一般初始状态驱动到目标状态的一般初始状态的时间 - 最佳协议，即，有一个具有界限的单个控制场。浴室和值之间的耦合是由Lindblad主方程建模的。耗散通常将系统驱动到最大混合状态。因此，通常存在一个最佳的进化时间，除了该消耗性阻止系统越来越接近目标状态。但是，对于某些特定的耗散通道，最佳控制可以使系统从无限长的最大熵状态中。详细讨论了这种特定情况下的条件。描述了构建时间优势协议的数值程序。特别是，这里采用的形式主义可以有效地评估时间依赖性的奇异控制，这对于控制一个孤立的量子或耗散量子至关重要。
A formalism based on Pontryagin's maximum principle is applied to determine the time-optimal protocol that drives a general initial state to a target state by a Hamiltonian with limited control, i.e., there is a single control field with bounded amplitude. The coupling between the bath and the qubit is modeled by a Lindblad master equation. Dissipation typically drives the system to the maximally mixed state; consequently, there generally exists an optimal evolution time beyond which the decoherence prevents the system from getting closer to the target state. For some specific dissipation channel, however, the optimal control can keep the system from the maximum entropy state for infinitely long. The conditions under which this specific situation arises are discussed in detail. The numerical procedure to construct the time-optimal protocol is described. In particular, the formalism adopted here can efficiently evaluate the time-dependent singular control which turns out to be crucial in controlling either an isolated or a dissipative qubit.
