Fluxonium Quantum Qubits Fabricated with 100 kV EBL System

In quantum computing, there is a need to scale up the number of qubits. However, their performance can be compromised by signal crosstalk between qubits and their connection to lossy control and readout circuitry. Recent work has been reported that seeks to address this problem by placing the fluxonium quantum qubits circuitry and control circuitry on separate chips, and connecting them in a bump bonded flip-chip package. This approach can improve qubit performance by not exposing the qubits to additional fabrication steps. Also, interconnects can be made more directly to the qubits rather than routing signals from the perimeter of the chip which helps reduce overlap between circuit elements.

This work was reported by Aaron Somoroff, Patrick Truitt, Adam Weis, Jacob Bernhardt, Daniel Yohannes, Jason Walter, Konstantin Kalashnikov, Mario Renzullo, Raymond Mencia, Maxim Vavilov, Vladmir E. Manucharyan, Igor Vernik, and Oleg Mukhanov in a collaborative effort from SEEQC, University of Maryland, University of Wisconsin-Madison, and École polytechnique fédérale de Lausanne, EPFL.

The quantum qubit chip patterning was accomplished with an STS-Elionix ELS-G100 100 kV electron beam lithography system.

Quantum chip with 4 fluxonium qubit superconducting circuits fabricated with an STS-Elionix 100kV EBL system.

For more information please see https://lnkd.in/gHM6-SRy.

Image (with permission from by the American Physical Society): (a) Quantum chip with 4 fluxonium qubit superconducting circuits comprised of Josephson junctions. (b) Carrier chip with control circuitry. (c) Quantum chip highlighted in red outline to be bump bonded in a flip-chip configuration with underlying carrier chip. (d) Simulation of total fluxonium shunt capacitance Csigma, fluxonium-resonator coupling capacitance Cqr, and fluxonium-drive line coupling capacitance Cdrive versus MCM gap distance d.