Cryogenic microwave measurement setup

目标是研究低温下的超导量子电路。虽然近年来的进展已经导致了高质量的量子系统，并且基于超导量子比特的第一个量子计算机原型已经实现，但为了能够实现实际效益，仍然需要进行大量的研究。然而，毫无疑问，对这种复杂量子系统的控制开辟了广泛的研究领域，从多体量子态的产生和研究到相关自旋系统的模拟，最终到有用量子算法的实现。具体的研究项目包括开发和表征几个量子比特之间的耦合元素，以便更有效地实现量子算法。另一个主题是通过最优控制和绝热协议的研究来改进量子比特操作，以研究量子状态神经网络的应用。为了实现这些研究目标，需要一个低温微波测量系统，该系统由一个基温为10mK的低温恒温器和适当的屏蔽组成。混合低温恒温器必须具有足够的冷却能力，样品量和电缆管道，以允许控制和测量多个量子位（计划多达15个量子位和耦合器）。量子比特的时间分辨控制需要快速任意波发生器（awg）和微波信号源。该测量基于一种纯差技术，其中量子系统的信息被编码在微波信号的边带中，经过数字化和集成后确定量子比特的状态。这需要在低温下使用AWG/数字化仪测量单元和微波组件（低噪声放大器，环行器和隔离器）。该测量系统将安装在瓦尔特-梅ß纳研究所（WMI），并将由Stefan Filipp团队运营，他将于2020年5月作为WMI主任和慕尼黑工业大学技术物理学正教授（W3）成立他的团队。该研究所的其他小组以及更广泛的研究网络（卓越集群，TUM研究所）中的小组将可以访问该系统。

The goal is to investigate superconducting quantum circuits at low temperatures. While the progress in recent years has led to high-quality quantum systems and the first quantum computer prototypes based on superconducting qubits have already been realized, there is still an immense need for research in order to be able to achieve a practical benefit. There is no doubt, however, that the control of such complex quantum systems opens up a broad spectrum of research, from the generation and investigation of many-body quantum states to the simulation of correlated spin systems and eventually to the implementation of useful quantum algorithms. Concrete research projects include the development and characterization of coupling elements between several qubits in order to implement quantum algorithms more efficiently. Another topic is the improvement of qubit operations through optimal control and the study of adiabatic protocols to investigate applications of quantum-regime neuronal networks.To achieve these research goals, a cryogenic microwave measurement system consisting of a cryostat with base temperature of 10mK and appropriate shielding is required. The mixing cryostat must have adequate cooling capacity, sample volume and cable ducts to allow for the control and measurement of multiple qubits (up to 15 qubits and couplers are planned). The time-resolved control of qubits requires fast arbitrary wave generators (AWGs) and microwave signal sources. The measurement is based on a homodyne technique, in which the information about the quantum system is encoded in the sidebands of a microwave signal and after digitization and integration the qubit state is determined. This requires a AWG/digitizer measuring unit and microwave components (low-noise amplifiers, circulators and isolators) at low temperatures.The measurement system will be installed at the Walther-Meißner-Institute (WMI) and will be operated by the group of Stefan Filipp, who will start his group in May 2020 as Director of the WMI and full professor (W3) for Technical Physics at the TU Munich. Other groups from the institute and as well as groups in the wider research network (Cluster of Excellence, TUM institutes) will have access to the system.