Observation and manipulation of quantum interference in a superconducting Kerr parametric oscillator

TL;DR

This paper reports the direct observation of quantum interference in a superconducting Kerr parametric oscillator, demonstrating key quantum properties and manipulation techniques crucial for quantum information processing.

Contribution

It provides the first direct visualization of quantum interference in a superconducting Kerr oscillator using Wigner tomography, advancing quantum control methods.

Findings

Observation of quantum interference via Wigner tomography

Mapping between Fock states and cat states

Demonstration of quantum gate operations

Abstract

Quantum tunneling is the phenomenon that makes superconducting circuits "quantum". Recently, there has been a renewed interest in using quantum tunneling in phase space of a Kerr parametric oscillator as a resource for quantum information processing. Here, we report a direct observation of quantum interference induced by such tunneling in a planar superconducting circuit through Wigner tomography. We experimentally elucidate all essential properties of this quantum interference, such as mapping from Fock states to cat states, a temporal oscillation due to the pump detuning, as well as its characteristic Rabi oscillations and Ramsey fringes. Finally, we perform gate operations as manipulations of the observed quantum interference. Our findings lay the groundwork for further studies on quantum properties of superconducting Kerr parametric oscillators and their use in quantum information technologies.