Cavity-Mediated Entanglement Generation Via Landau-Zener Interferometry

TL;DR

This paper demonstrates quantum control and entanglement generation between two transmon qubits mediated by a cavity, using Landau-Zener interferometry to produce Bell states with high fidelity.

Contribution

It introduces a novel method of entanglement generation via cavity-mediated Landau-Zener transitions and interference, with experimental validation and control over the process.

Findings

Single passage through the avoided crossing tests Landau-Zener formula

Interference patterns show tunable visibility via level velocity

Bell state generated with 78% fidelity limited by qubit relaxation

Abstract

We demonstrate quantum control and entanglement generation using a Landau-Zener beam splitter formed by coupling two transmon qubits to a superconducting cavity. Single passage through the cavity-mediated qubit-qubit avoided crossing provides a direct test of the Landau-Zener transition formula. Consecutive sweeps result in Landau-Zener-Stuckelberg interference patterns, with a visibility that can be sensitively tuned by adjusting the level velocity through both the non-adiabatic and adiabatic regimes. Two-qubit state tomography indicates that a Bell state can be generated via a single passage, with a fidelity of 78% limited by qubit relaxation.