论文标题

成对测量诱导量子相干性的合成

Pairwise Measurement Induced Synthesis of Quantum Coherence

论文作者

Gumberidze, Mariia, Kolář, Michal, Filip, Radim

论文摘要

具有不同能量的状态的量子相干叠加,即相对于能量基础相干的状态,是现代量子技术的重要资源。由于弱相干驱动的效果,或者由于环境的存在,可以自主获得具有较小连贯性的状态。在本文中,我们提出了一种基于测量的协议,用于从单个系统(低初始相干性)中构成量子相干性的合成,以进入关节系统的全局(且较高)的连贯性。作为输入,它使用$ N $非相互作用的两级系统(TLS)的非相互作用副本,初始能量和连贯性低。这些可以由弱的外部驱动器提供,也可以由与浴室的互动产生。该协议有条件地综合具有比初始状态更高的能量和连贯性的输出状态,代表了一个通用过程,该过程尚未对规则进行很好的研究。除了能量和连贯性外,我们还研究了称为相互连贯性的数量,也显示了协议应用后的增加。这种方法基于在TLS对(有条件地删除其基态)上的顺序成对投影测量值,这些测量在TLS能量基础上是对角线的。相干合成的功能相对于TLS环境对系统的脱去作用是可靠的。我们的方法可能显示出其在量子传感,量子电池充电或其他应用程序中的好处,在这些应用中,从较小(较弱)的资源合成较大的相干系统很有用。

Quantum coherent superpositions of states with different energies, i.e., states with coherence with respect to energy basis, are important resource for modern quantum technologies. States with small coherence can be obtained either autonomously, due to the effect of a weak coherent drive or, potentially, due to the presence of an environment. In this paper, we propose a measurement-based protocol for quantum coherence synthesis from individual systems (with low initial coherence) into a global (and higher) coherence of the joint system. As an input, it uses $N$ non-interacting copies of two-level systems (TLS), with low initial energy and coherence. These can be supplied by, e.g., a weak external drive or can result from an interaction with a bath. This protocol conditionally synthesizes an output state with higher energy and coherence than the initial state had, representing an universal process whose rules have not been well studied, yet. In addition to energy and coherence, we study the quantity called mutual coherence, showing increase after the protocol application, as well. This approach is based on application of sequential pairwise projective measurements on TLS pairs (conditionally removing their ground states), that are diagonal in the TLS energy basis. The functionality of the coherence synthesis is robust with respect to dephasing effects of the TLS environment on the system. Our approach may show its benefits in quantum sensing, quantum batteries charging, or other applications where synthesis of a larger coherent system from smaller (weaker) resources is useful.

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