Berlin 2024 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 41: Superconducting Qubits (joint session QI/TT)
TT 41.9: Talk
Wednesday, March 20, 2024, 11:45–12:00, HFT-FT 131
High-Fidelity Readout of Fluxonium Qubits — •Florian Wallner1,2, Johannes Schirk1,2, Niklas Bruckmoser1,2, Leon Koch1,2, Ivan Tsitsilin1,2, Niklas Glaser1,2, Vincent Koch1,2, Longxiang Huang1,2, Klaus Liegener1,2, Max Werninghaus1,2, Christian Schneider1,2, and Stefan Filipp1,2 — 1Technical University of Munich, TUM School of Natural Sciences, Physics Department, Garching, Germany — 2Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany
Fast and high-fidelity qubit readout is one of the fundamental operations for quantum computation. A higher readout fidelity significantly reduces the number of experiments needed to reach the specified accuracy. Recently, the use of measurements in a mid-circuit fashion with classical feedback became an important resource for efficient quantum circuits. Here the performance of the readout is even more critical for the resulting circuit fidelity. In this talk we report on our recent advances to improve the readout of superconducting Fluxonium qubits. We demonstrate dispersive readout within 1.2 µs with assiment fidelities higher than 98.3 % and a QNDness of up to 98.0 %. These high numbers enable us to use an active feedback based reset that outperforms passive methods to initialize the qubit. Due to our high readout photon number of n>50 we can mitigate the use of a parametric amplifier. Moreover, through dedicated flux pulses we can utilize the dispersive shift landscape of the qubits. With this, we can protect the qubit during idling times and significantly enhance the resonator shift during readout improving the readout fidelity even further.
Keywords: Superconducting Qubits; Qubit Readout