D-Wave has announced some early results from a test chip it has developed to characterize the fluxonium superconducting qubits it plans on using. D-Wave has taken a different path from some of the other superconducting processor manufacturers including IBM, Google, Rigetti, and others who are using what are called transmon qubits. The fluxonium approach is more recent and it combines features of both flux and charge qubit circuits.
D-Wave believes that the fluxonium approach may prove superior to transmons because they can potentially offer better relaxation (T1) coherence times, provide a larger separation between low and high energy states resulting in lower state leakage, and operate at considerably lower frequencies which simplifies the control complexity. D-Wave is currently characterizing the chip and have reported early measures of T1 (relaxation) times in the 100 microsecond range, T2R (Ramsey dephasing times) in the 10 microsecond range, and an effective fluxonium temperature of 18 millikelvin.
D-Wave indicates they are quite pleased with this progress as these early results are already comparable to other fluxonium circuits that have been reported in the literature. The company has issued a press release to announce these early results available here and has also posted a technical paper with additional data on their website which can be seen here.
September 13, 2023