Single-photon terahertz (THz) detection is one of the most demanding technologies for a variety of fields and could lead to many breakthroughs. Although significant progress has been made in the past two decades, operating it at room temperature still remains a great challenge. Here, we demonstrate, for the first time, a room temperature THz detector at single-photon levels based on nonlinear wave mixing in thermal Rydberg atomic vapor. The low-energy THz photons are coherently upconverted to high-energy optical photons via a nondegenerate Rydberg state involved in a six-wave mixing process, and therefore, single-photon THz detection is achieved by a conventional optical single-photon counting module. The noise equivalent power of such a detector reaches 9.5 × 10−19 W/Hz1/2, which is more than four orders of magnitude lower than the state-of-the-art room temperature THz detectors. The optimum quantum efficiency of the whole-wave mixing process is about 4.3%, with 40.6 dB dynamic range, and the maximum conversion bandwidth is 172 MHz, which is all-optically controllable. The developed fast and continuous-wave single-photon THz detector at room temperature operation has a great potential for portability and chip-scale integration, and could be revolutionary for a wide range of applications in remote sensing, wireless communication, biomedical diagnostics, and quantum optics.

中文翻译：

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使用热里德堡原子进行室温单光子太赫兹探测


单光子太赫兹 （THz） 检测是各个领域要求最苛刻的技术之一，可能会带来许多突破。尽管在过去二十年中取得了重大进展，但在室温下运行仍然是一项巨大的挑战。在这里，我们首次展示了基于热里德堡原子蒸气中非线性波混合的单光子水平室温太赫兹探测器。低能太赫兹光子通过参与六波混频过程的非简并里德伯状态相干地上转换为高能光学光子，因此，单光子太赫兹检测是通过传统的光学单光子计数模块实现的。这种探测器的噪声等效功率达到 9.5 × 10−19 W/Hz1/2，比最先进的室温太赫兹探测器低四个数量级以上。全波混频过程的最佳量子效率约为 4.3%，动态范围为 40.6 dB，最大转换带宽为 172 MHz，全光可控。开发的室温操作快速连续波单光子太赫兹探测器具有巨大的便携性和芯片级集成潜力，对于遥感、无线通信、生物医学诊断和量子光学等广泛应用来说，可能具有革命性意义。