Frequency-resolved decoherence spectroscopy of a semiconductor charge qubit coupled to a high-impedance resonator
Abstract
Superconducting resonators coupled to semiconductor quantum dots provide a powerful platform to investigate light-matter interaction and decoherence mechanisms in solid-state quantum systems. Here we study a hybrid circuit quantum electrodynamics architecture consisting of a GaAs double-quantum-dot charge qubit capacitively coupled to a high-impedance, frequency-tunable SQUID-array resonator. By tuning the qubit transition frequency over the range $ω_\mathrm{q}/2π\sim 3$-$6$ GHz, we perform frequency-resolved decoherence spectroscopy of the charge qubit across a broad energy window. Time-resolved measurements enable us to disentangle relaxation and pure dephasing processes and to identify distinct decoherence regimes as a function of qubit frequency. We find that at lower frequencies ($\leq 4.5$ GHz) dephasing dominates the qubit linewidth, whereas at higher frequencies energy relaxation becomes the leading contribution. The measured frequency dependence of the relaxation rate exhibits a cubic scaling, consistent with charge-qubit decay dominated by coupling to a piezoelectric phonon bath and providing frequency-resolved access to the corresponding phonon-induced spectral density. Our results show that hybrid semiconductor--superconducting circuits can serve as sensitive spectroscopic tools to probe microscopic decoherence mechanisms relevant for a wide range of hybrid quantum devices.
Authors 13
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Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
Quantum Center , ETH Zürich , CH-8093 Zürich , Switzerland
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École Polytechnique Fédérale de Lausanne
Affiliation as printed
Center for Quantum Science and Engineering , Institute of Physics , École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne , Switzerland
Hybrid Quantum Circuits Laboratory (HQC) , Institute of Physics , École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne , Switzerland
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Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
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Affiliation as printed
NanoLund and Solid State Physics , Lund University , Box 118 , 22100 Lund , Sweden
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QuTech · Delft University of Technology
Affiliation as printed
QuTech and Kavli Institute of Nanoscience , Delft University of Technology , Lorentzweg 1 , 2628 CJ Delft , The Netherlands
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Affiliation as printed
Lorentz Institute and Leiden
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Norwegian University of Science and Technology
Affiliation as printed
Department of Physics , Norwegian University of Science and Technology , NO-7491 , Trondheim , Norway
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Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
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ETH Zurich · Delft University of Technology
Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
Microsoft Quantum Lab Delft , Lorentzweg 1 , 2628 CJ Delft , The Netherlands
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Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
Quantum Center , ETH Zürich , CH-8093 Zürich , Switzerland
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Affiliation as printed
Department of Physics , ETH Zurich , CH-8093 Zurich , Switzerland
Quantum Center , ETH Zürich , CH-8093 Zürich , Switzerland
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École Polytechnique Fédérale de Lausanne
Affiliation as printed
Center for Quantum Science and Engineering , Institute of Physics , École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne , Switzerland
Hybrid Quantum Circuits Laboratory (HQC) , Institute of Physics , École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne , Switzerland
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