Cryogenic microwave measurement setup

• Subject Area: Condensed Matter Physics
• Term: Funded in 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 444750395

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.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Tieftemperatur Mikrowellenmesseinheit
• Instrumentation Group: 8550 Spezielle Kryostaten (für tiefste Temperaturen)
• Applicant Institution: Technische Universität München (TUM)
• Leader: Professor Dr. Stefan Filipp