Non-Markovian dynamics of a superconducting qubit in a phononic bandgap

TL;DR

This paper demonstrates a novel phononic bandgap platform that suppresses TLS-mediated phonon emission, leading to non-Markovian dynamics and extended qubit relaxation times in superconducting qubits.

Contribution

It introduces a phononic bandgap metamaterial to engineer qubit-TLS interactions, achieving non-Markovian dynamics and longer qubit lifetimes.

Findings

Observation of non-Markovian qubit dynamics within the phononic bandgap

Qubit lifetime extended to 34 microseconds due to phonon engineering

Suppression of TLS-mediated phonon emission in superconducting qubits

Abstract

The overhead to construct a logical qubit from physical qubits rapidly increases with the decoherence 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 $\mu s$. We discuss the implications of these observations for extending qubit relaxation times through simultaneous phonon protection and miniaturization.