Parametric interaction induced avoided dressed state crossings in cavity QED:generation of quantum coherence and equally weighted superposition of Fock states

TL;DR

This paper introduces a novel cavity QED approach using parametric couplings to induce avoided crossings in dressed states, enabling high-fidelity superpositions of Fock states and strong entanglement.

Contribution

It demonstrates how parametric interactions can convert dressed state crossings into avoided crossings, facilitating quantum coherence, superposition, and entanglement generation in cavity QED.

Findings

Quantum beats with improved quality via adiabatic switching

Superpositions of Fock states with over 95% fidelity

Cavity-qubit entanglement with concurrence exceeding 90%

Abstract

We present a new paradigm in the field of cavity QED by bringing out remarkable features associated with the avoided crossing of the dressed state levels of the Jaynes Cummings model. We demonstrate how the parametric couplings, realized by a second order nonlinearity in the cavity, can turn the crossing of dressed states into avoided crossings. We show how one can generate coherence between the avoided crossing of dressed states. Such coherences result, for example, in quantum beats in the excitation probability of the qubit. The quality of quantum beats can be considerably improved by adiabatically turning on the parametric interaction. We show how these avoided crossings can be used to generate superpositions of even or odd Fock states with the remarkable property of equal weights for the states in superposition. The fidelity of generation is more than 95\%. In addition, we show strong entanglement between the cavity field and the qubit with the concurrence parameter exceeding 90\%.