Kavli Affiliate: Irfan Siddiqi
| First 5 Authors: Larry Chen, Kan-Heng Lee, Chuan-Hong Liu, Brian Marinelli, Ravi K. Naik
| Summary:
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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