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Scalable and Site-Specific Frequency Tuning of Two-Level System Defects in Superconducting Qubit Arrays

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arxiv 2503.04702 v1 pith:B3KDNCZW submitted 2025-03-06 quant-ph

classification quant-ph
keywords qubitquantumqubitssinglecontroldefectssuperconductingaverage
verification ladder T0 review T1 audit T2 compute T3 formal
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abstract

State-of-the-art superconducting quantum processors containing tens to hundreds of qubits have demonstrated the building blocks for realizing fault-tolerant quantum computation. Nonetheless, a fundamental barrier to scaling further is the prevalence of fluctuating quantum two-level system (TLS) defects that can couple resonantly to qubits, causing excess decoherence and enhanced gate errors. Here we introduce a scalable architecture for site-specific and in-situ manipulation of TLS frequencies out of the spectral vicinity of our qubits. Our method is resource efficient, combining TLS frequency tuning and universal single qubit control into a single on-chip control line per qubit. We independently control each qubit's dissipative environment to dynamically improve both qubit coherence times and single qubit gate fidelities -- with a constant time overhead that does not scale with the device size. Over a period of 40 hours across 6 qubits, we demonstrate a $36\%$ improvement in average single qubit error rates and a $17\%$ improvement in average energy relaxation times. Critically, we realize a 4-fold suppression in the occurrence of TLS-induced performance outliers, and a complete reduction of simultaneous outlier events. These results mark a significant step toward overcoming the challenges that TLS defects pose to scaling superconducting quantum processors.

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Cited by 5 Pith papers

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  4. Non-equilibrium Dynamics of Two-level Systems directly after Cryogenic Alternating Bias

    quant-ph 2025-09 conditional novelty 6.0 of 10

    Cryogenic alternating voltage bias scrambles the frequencies of strongly coupled two-level systems in amorphous alumina, an effect reversed by thermal cycling above 10 K.

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