Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA.
Energy Sciences Institute, Yale University, New Haven, Connecticut 06511, USA.
Phys Rev Lett. 2021 Sep 10;127(11):110506. doi: 10.1103/PhysRevLett.127.110506.
Active control of quantum systems enables diverse applications ranging from quantum computation to manipulation of molecular processes. Maximum speeds and related bounds have been identified from uncertainty principles and related inequalities, but such bounds utilize only coarse system information and loosen significantly in the presence of constraints and complex interaction dynamics. We show that an integral-equation-based formulation of conservation laws in quantum dynamics leads to a systematic framework for identifying fundamental limits to any quantum control scenario. We demonstrate the utility of our bounds in three scenarios-three-level driving, decoherence suppression, and maximum-fidelity gate implementations-and show that in each case our bounds are tight or nearly so. Global bounds complement local-optimization-based designs, illuminating performance levels that may be possible, as well as those that cannot be surpassed.
量子系统的主动控制使得从量子计算到分子过程的操纵等各种应用成为可能。最大速度和相关的界限已经从不确定性原理和相关的不等式中确定，但这些界限只利用了粗糙的系统信息，并且在存在约束和复杂相互作用动力学的情况下会显著放宽。我们表明，量子动力学中守恒定律的积分方程表述导致了一种系统的框架，可以确定任何量子控制场景的基本限制。我们在三个场景中展示了我们界限的实用性——三能级驱动、退相干抑制和最大保真度门实现——并表明在每种情况下我们的界限都是紧的或几乎是紧的。全局界限补充了基于局部优化的设计，阐明了可能达到的性能水平，以及那些无法超越的性能水平。
