Quantum superposition of energy eigenstates can appear autonomously in a single quantum two-level system coupled to a low-temperature thermal bath, if such coupling has a proper composite nature. We propose here a principally different and more feasible approach employing engineered interactions between two-level systems being thermalized into a global Gibbs state by weakly coupled thermal bath at temperature T. Therefore, in such case quantum coherence appears by a different mechanism, whereas the system-bath coupling does not have to be engineered. We demonstrate such autonomous coherence generation reaching maximum values of coherence. Moreover, it can be alternatively built up by using weaker but collective interaction with several two-level systems. This approach surpasses the coherence generated by the engineered system-bath coupling for comparable interaction strengths and directly reduces phase estimation error in quantum sensing. This represents a necessary step towards the autonomous quantum sensing.

中文翻译：

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通过热系统内耦合实现局部相干


如果这种耦合具有适当的复合性质，则能量本征态的量子叠加可以在耦合到低温热浴的单量子两能级系统中自主出现。我们在这里提出了一种主要不同且更可行的方法，利用两能级系统之间的工程相互作用，通过温度为 T 的弱耦合热浴将其热化为全局吉布斯态。因此，在这种情况下，量子相干性通过不同的机制出现，而系统- 无需设计浴槽耦合器。我们证明了这种自主相干生成达到了相干性的最大值。此外，它还可以通过与多个两能级系统使用较弱但集体的相互作用来构建。这种方法超越了工程系统-浴耦合产生的相干性，以达到可比较的相互作用强度，并直接减少了量子传感中的相位估计误差。这是迈向自主量子传感的必要一步。