Numerical simulation of leakage effect for quantum NOT operation on three-Josephson-junction flux qubit

TL;DR

This paper uses numerical simulations to analyze the leakage effect during quantum NOT operations on three-Josephson-junction flux qubits, finding it to be manageable with proper pulse shaping.

Contribution

It applies the imaginary time evolution method to accurately model flux qubits and investigates the leakage effect under different pulse shapes during quantum operations.

Findings

Leakage effect is not a serious problem for flux qubits.

Gaussian-shaped pulses reduce leakage compared to hard-shaped pulses.

Accurate wave functions and eigenenergies are obtained through the simulation.

Abstract

Superconducting flux qubits with three Josephson junctions are promising candidates for the building blocks of a quantum computer. We have applied the imaginary time evolution method to study the model of this qubit accurately by calculating its wave functions and eigenenergies. Because such qubits are manipulated with magnetic flux microwave pulses they might be irradiated into non-computational states which is called the leakage effect. Through the evolution of the density matrix of the qubit under either hard-shaped pulse or Gaussian-shaped pulse to carry out quantum NOT operation, we show that the leakage effect is not a serious problem for a flux qubit.