Dipole blockade without dipole-dipole interaction

TL;DR

This paper introduces a new mechanism for achieving dipole blockade in quantum systems without relying on dipole-dipole interactions, using cavity-coupled qubits driven by a coherent field, which could enhance quantum information processing.

Contribution

It proposes a novel physical mechanism for dipole blockade without dipole-dipole interaction, involving cavity-coupled qubits and tailored decay rates.

Findings

Successful suppression of unwanted excitation pathways.

Strong entanglement between qubits over a broad parameter range.

Photon bunching as a signature of dipole blockade.

Abstract

The dipole blockade phenomenon is a direct consequence of strong dipole-dipole interaction, where only single atom can be excited because the doubly excited state is shifted out of resonance. The corresponding two-body entanglement with non-zero concurrence induced by the dipole blockade effect is an important resource for quantum information processing. Here, we propose a novel physical mechanism for realizing dipole blockade without the dipole-dipole interaction, where two qubits coupled to a cavity, are driven by a coherent field. By suitably chosen placements of the qubits in the cavity and by adjusting the relative decay strengths of the qubits and cavity field, we kill many unwanted excitation pathways. This leads to dipole blockade. In addition, we show that these two qubits are strongly entangled over a broad regime of the system parameters. We show that a strong signature of this dipole blockade is the bunching property of the cavity photons which thus provides a possible measurement of the dipole blockade. We present dynamical features of the dipole blockade without dipole-dipole interaction. The proposal presented in this work can be realized not only in traditional cavity QED, but also in non-cavity topological photonics involving edge modes.