Phonon-Protected Superconducting Qubits


The overhead to construct a logical qubit from physical qubits rapidly increases with the de- coherence rate. Current superconducting qubits reduce dissipation due to two-level systems (TLSs) by using large device footprints. However, this approach provides partial protection, and results in a trade-off between qubit footprint and dissipation. This work introduces a new platform using phononics to engineer superconducting qubit-TLS interactions. We realize a superconducting qubit on a phononic bandgap metamaterial that suppresses TLS- mediated phonon emission. We use the qubit to probe its thermalization dynamics with the phonon-engineered TLS bath. Inside the phononic bandgap, we observe the emergence of non-Markovian qubit dynamics due to the Purcell-engineered TLS lifetime of 34 μs. We discuss the implications of these observations for extending qubit relaxation times through simultaneous phonon protection and miniaturization.

Publication date: 
December 14, 2023
Publication type: 
Ph.D. Dissertation
Mutasem Odeh EECS Department University of California, Berkeley Technical Report No. UCB/EECS-2023-269 December 14, 2023

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