Far-off resonance conditional phase-shifter using the ac-Stark shift

TL;DR

This paper introduces a technique using ac Stark shifts in a V-system to achieve a pi phase shift between weak lasers at the 1000-photon level, enabling precise quantum control.

Contribution

It presents a novel method for conditional phase shifting using far-off resonant lasers and ac Stark effects in a V-system, which is simpler and effective.

Findings

Achieves pi phase shift with lasers at 1000-photon level

Uses ac Stark shift in a V-system for phase control

Provides a feasible approach for quantum information processing

Abstract

We propose a simple technique that achieves a conditional phase shift of pi radians between two weak lasers with energies at the 1000-photon level. The key idea is to set up a V-system with two far-off resonant lasers by coupling the ground state to two excited electronic states. The lasers interact through the ac Stark shift of the ground state and thereby acquire a large conditional phase shift.