最大化在各向异性环境中演化的量子比特的纯度
Maximizing the purity of a qubit evolving in an anisotropic environment
摘要：
我们提供了一个通用的方法来计算和最大化与各向异性非马尔可夫环境相互作用的量子比特的纯度。与直觉相反，我们发现纯度通常通过将量子比特准备和存储在非相互作用本征态的叠加中来最大化。对于与量子点中重空穴自旋量子比特的退相干或双量子点中两个电子的单重态-三重态量子比特相关的模型，我们证明了在其非相互作用的基态中制备量子比特实际上是最大化纯度的最差选择。我们进一步给出了量子点中空穴自旋的任意自旋分量的自旋回波包络调制的解析结果，超出了标准的久期近似。我们占一般动力学的存在下，一个纯粹的退相过程，并确定一个交叉的时间尺度，它再次是有利的初始化量子比特在非相互作用的基态。最后，我们考虑一个一般的两轴动态解耦序列，并确定初始条件，最大限度地提高纯度，最大限度地减少泄漏到环境中。
英文摘要：
We provide a general method to calculate and maximize the purity of a qubit interacting with an anisotropic non-Markovian environment. Counter to intuition, we find that the purity is often maximized by preparing and storing the qubit in a superposition of non-interacting eigenstates. For a model relevant to decoherence of a heavy-hole spin qubit in a quantum dot or for a singlet-triplet qubit for two electrons in a double quantum dot, we show that preparation of the qubit in its non-interacting ground state can actually be the worst choice to maximize purity. We further give analytical results for spin-echo envelope modulations of arbitrary spin components of a hole spin in a quantum dot, going beyond a standard secular approximation. We account for general dynamics in the presence of a pure-dephasing process and identify a crossover timescale at which it is again advantageous to initialize the qubit in the non-interacting ground state. Finally, we consider a general two-axis dynamical decoupling sequence and determine initial conditions that maximize purity, minimizing leakage to the environment.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
