Acquisition of a MEB 550S HV e-beam deposition system

The contracting institution is the Niels Bohr Institute at University of Copenhagen. The tool will become part of the low-temperature fabrication and cleanroom infrastructure facilities already available at Center for Quantum Devices.

We intend to procure a low-pressure, high-purity evaporation chamber specifically suited for high-coherence, highly reproducible Aluminum-based Josephson junction. The tool will be used for superconducting qubit and quantum photonics research at the Niels Bohr Institute and will be a part of the general infrastructure available to the low-temperature physics experiment.

This specific evaporation tool we require for our research is focused solely on high yield, high reproducibility, high-coherence compatible Aluminum-based Josephson junctions for superconducting qubits. Specifically, we require sub 5% variation in critical currents of Josephson junctions across waferscale (>5cm^2) fabrication. This was demonstrated by Kreikebaum et al, Supercond. Sci. and Technol., 33, 6 (2020) using the Plassys MEB 550s. Crucial is the high coherence of the resulting qubits as well. While the qubit coherence is dependent on many optimization parameters on top of the evaporation tool, proven demonstration of >100 microsecond T1 times is also necessary for our research, which has also been achieved using the MEB 550s (e.g. by Place et al, Nat. Comm., 1779, 12 (2021). Together, the proven stability, reproducibility and high-coherence compatiblity enabled by using the Plassys MEB550s is unparalleled and represents a central feature of our planned research.

Our resesarch is focused on high-coherence superconducting qubits for which the Plassys evaporator is an industry standard. The proven demonstrations of high-fidelity and reproducibility with a Plassys evaporator is integral to the future research of our group towards multi-qubit systems. Because of our specific research aims, the reproducibility is a fundamental aspect of the planned projects thus enhancing the central importance acquisition of an evaporator with proven performance.