Ultrahigh-vacuum cryostat für hybrid quantum experiments with ultracold Rydberg atoms

提出了一种用于实现和研究由超冷里德堡原子耦合到固态机电系统的量子杂化系统的装置。该装置将用于研究量子力学中的基本问题，如退相干和经典物理与量子物理之间的转换。同时，还将研究和开发在基于微波的固态量子计算机和单光子编码的飞行量子比特之间操作和传输量子信息的新方法。整个装置以超高真空低温恒温器为中心，一方面可以产生和处理磁和光捕获的超冷原子，另一方面可以操作机电谐振器和超导电路。整个装置的其他部件包括用于Rb原子的光学冷却和捕获以及里德堡激发的激光器，微波信号发生器，用于在GHz频率范围内激励和读出机电系统的网络分析器，以及用于测量光光子与固体系统中的单微波光子或声子之间的光子-光子关联和纠缠的8通道单光子探测器。建议的组件将与在室温真空室中研究里德堡激发的前一种设置相结合。计划在低温环境中进行的实验是利用里德堡-里德堡相互作用和里德堡阻塞机制的一种全新的方法。几年来，我们的团队已经成功地使用这一机制在单光子水平上产生了光学非线性，并由此产生了单光子之间的有效相互作用。这允许实现量子光学开关元件，如晶体管和单光子逻辑门，它们是量子信息设置的中心组件。在这个新的装置中，我们正在推进的方法将被应用于一个全新的量子系统--微机械振荡器(MEMS)。例如，光学非线性将被用来产生和读出MEMS的非经典振荡态。除了有关“大”物体的量子力学的基本问题外，量子领域的MEMS作为超导量子计算机的量子传感器和量子信息存储设备也引起了人们的极大兴趣。特别是，我们的研究项目旨在实现微波量子计算机的光学接口，使这些机器能够远距离联网。

An apparatus for the realization and investigation of quantum hybrid systems consisting of ultracold Rydberg atoms coupled to solid-state electromechanical systems is proposed. The apparatus will be used to investigate fundamental issues in quantum mechanics such as decoherence and transition between classical and quantum physics. At the same time, novel methods for manipulating and transferring quantum information between microwave-based solid-state quantum computers and "flying" qubits encoded in single optical photons will be investigated and developed. The overall apparatus consists centrally of an ultra-high vacuum cryostat in which, on the one hand, magnetically and optically trapped ultracold atoms can be generated and processed and, on the other hand, electromechanical resonators and superconducting circuits can be operated. Other components of the overall apparatus include lasers for optical cooling and trapping and for Rydberg excitation of rubidium atoms, a microwave signal generator, a network analyzer for excitation and readout of the electromechanical systems in the GHz frequency range, and an 8-channel single photon detector for measuring photon-photon correlations and entanglement between optical photons and single microwave photons or phonons in the solid-state system. The proposed components will be combined with a predecessor setup in which Rydberg excitations were studied in a room temperature vacuum chamber. The planned experiments in a cryogenic environment are a fundamentally new approach to exploiting Rydberg-Rydberg interactions and the Rydberg blockade mechanism. Our group has been successfully using this mechanism for several years to generate optical nonlinearities at the single photon level and resulting effective interactions between single photons. This allows the realization of quantum optical switching elements such as transistors and single photon logic gates, which are a central component of quantum information setups. In this new apparatus, the approach we are advancing will be applied to an entirely new quantum system, a micro-mechanical oscillator (MEMS). For example, optical nonlinearity will be used to generate and read out non-classical oscillatory states of the MEMS. In addition to fundamental questions about the quantum mechanics of "large" objects, MEMS in the quantum regime are of great interest as quantum sensors and quantum information storage devices for superconducting quantum computers. In particular, our research project aims at the realization of an optical interface for microwave quantum computers, which enables the networking of these machines over long distances.