We present a quantum thermometry scheme based on a cavity-QED setup, which attains a sensitivity with Heisenberg scaling. A stream of identical two-level systems passes through a thermal bath to be tested. Each system partially thermalizes, carrying information on the temperature of the thermal bath, and it then interacts with a dissipative single-mode cavity. The Heisenberg scaling is attained from the initial coherence of each system. The systems cannot be fully thermalized by the thermal bath. The optimal interaction time between the system and the thermal bath is derived. Direct photon detection is proved to be an optimal measurement when there is no extra thermal bath in the cavity. In the case where there is an extra thermal bath in the cavity independent of the thermal bath to be tested, homodyne detection is the optimal measurement. Moreover, we show that direct photon detection obtains less information in the case where the extra thermal bath in the cavity is in thermal equilibrium with the thermal bath. However, the optimal measurement can utilize the information from the extra thermal bath to improve the estimation precision of the temperature.

中文翻译：

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基于腔QED设置的量子测温

我们提出一种基于腔QED设置的量子测温方案，该方案可通过Heisenberg缩放获得灵敏度。相同的两级系统流通过热浴进行测试。每个系统进行部分热化处理，并携带有关热浴温度的信息，然后与耗散的单模腔相互作用。海森堡定标是通过每个系统的初始相干来实现的。系统无法通过热水浴完全加热。得出系统与热浴之间的最佳相互作用时间。当腔中没有额外的热浴时，直接光子检测被证明是最佳测量。在型腔中有一个独立于要测试的热浴池的额外热浴池，零差检测是最佳的测量方法。此外，我们表明在腔中额外的热浴与热浴处于热平衡的情况下，直接光子检测获得的信息较少。然而，最佳测量可以利用来自额外热浴的信息来提高温度的估计精度。