Leakage suppression by ultrafast pulse shaping

TL;DR

This paper presents a method using ultrafast pulse shaping to suppress leakage in a three-level quantum system, enabling high-fidelity qubit control with minimal additional resources, validated by experiments with atomic rubidium.

Contribution

It introduces a pulse shaping technique that suppresses leakage to the third level without extra pulse-area cost, advancing quantum control methods.

Findings

Leakage suppressed up to first order of perturbation.

Experimental validation with shaped femtosecond pulses and rubidium atoms.

Good agreement between theory and experiment.

Abstract

We consider the leakage suppression problem of a three-level system in which the first two levels are the qubit system and the third, weakly-coupled to the second, is the leakage state. We show that phase- and amplitude-controlled two (three) pulses are sufficient for arbitrary qubit controls from the ground (an arbitrary) initial state, with leakage suppressed up to the first order of perturbation without additional pulse-area cost. A proof-of-principle experiment was performed with shaped femtosecond optical pulses and atomic rubidium showing a good agreement with the theory.