Landau-Zener Transitions in an Adiabatic Quantum Computer

TL;DR

This paper experimentally investigates Landau-Zener transitions in a single flux qubit within a multi-qubit superconducting chip, confirming theoretical predictions under specific noise and temperature conditions.

Contribution

It demonstrates a method to isolate and measure Landau-Zener transitions in a flux qubit, validating theoretical models in a realistic quantum computing environment.

Findings

High agreement with theoretical Landau-Zener transition probabilities

Effective isolation of a single qubit in a multi-qubit chip

Confirmation of 1/f magnetic flux noise impact on transition behavior

Abstract

We report an experimental measurement of Landau-Zener transitions on an individual flux qubit within a multi-qubit superconducting chip designed for adiabatic quantum computation. The method used isolates a single qubit, tunes its tunneling amplitude Delta into the limit where Delta is much less than both the temperature T and the decoherence-induced energy level broadening, and forces it to undergo a Landau-Zener transition. We find that the behavior of the qubit agrees to a high degree of accuracy with theoretical predictions for Landau-Zener transition probabilities for a double-well quantum system coupled to 1/f magnetic flux noise.