Giant-atom quantum acoustodynamics in hybrid superconducting-phononic integrated circuits

TL;DR

This paper demonstrates a giant atom in a hybrid superconducting-phononic circuit, revealing non-Markovian dynamics and enabling high-purity quantum state preparation, advancing quantum information processing capabilities.

Contribution

It introduces a novel giant-atom system in phononic circuits with tunable dissipation and non-Markovian effects, expanding quantum acoustodynamics research.

Findings

Observed non-Markovian relaxation dynamics with phonon backflow.

Achieved a frequency-dependent decay rate with a four-fold variation.

Prepared high-purity quantum superposition states.

Abstract

We demonstrate a giant atom by coupling a superconducting transmon qubit to a lithium niobate phononic waveguide at two points separated by about 600 acoustic wavelengths, with a propagation delay of 125 ns. The giant atom yields non-Markovian relaxation dynamics characterized by phonon backflow and a frequency-dependent effective decay rate varying four-fold over merely 4 MHz, corresponding to a Purcell factor exceeding 40. Exploiting this frequency-dependent dissipation, we prepare quantum superposition states with high purity. Our results establish phononic integrated circuits as a versatile platform for giant-atom physics, providing highly tunable quantum devices for advanced quantum information processing.