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arXiv:2203.13810 · Optics Letters

Fano effect induced giant and robust enhancement of photon correlations in cavity QED systems

Yuwei Lu, Jing-Feng Liu, Runhua Li, Haishu Tan, Yongyao Li

Published Jun 16, 2022• 3 citations
arXivHTMLPDF

Abstract

The Fano effect arising from the interference between two dissipation channels of the radiation continuum enables tuning of the photon statistics. Understanding the role of the Fano effect and exploiting it to achieve strong photon correlations are of both fundamental and applied significance. We present an analytical description of Fano-enhanced photon correlations based on cavity quantum electrodynamics to show that the Fano effect in atom-cavity systems can improve the degree of antibunching by over four orders of magnitude. The enhancement factors and the optimal conditions are explicitly given, and found to relate to the Fano parameter q. Remarkably, the Fano enhancement manifests robustness against the decoherence processes and can survive in the weak coupling regime. We expect our work to provide insight to tuning the photon statistics through the Fano effect, which offers a new, to the best of our knowledge, route to enhance the photon correlations, as well as the possibility of generating nonclassical light in a wider diversity of systems without the need of a strong light-matter interaction.

DOI
10.1364/ol.459643

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The Fano effect arising from the interference between two dissipation channels of the radiation continuum enables tuning of the photon statistics. Understanding the role of the Fano effect and exploiting it to achieve strong photon correlations are of both fundamental and applied significance. We present an analytical description of Fano-enhanced photon correlations based on cavity quantum electrodynamics to show that the Fano effect in atom-cavity systems can improve the degree of antibunching by over four orders of magnitude. The enhancement factors and the optimal conditions are explicitly given, and found to relate to the Fano parameter q. Remarkably, the Fano enhancement manifests robustness against the decoherence processes and can survive in the weak coupling regime. We expect our work to provide insight to tuning the photon statistics through the Fano effect, which offers a new, to the best of our knowledge, route to enhance the photon correlations, as well as the possibility of generating nonclassical light in a wider diversity of systems without the need of a strong light-matter interaction.
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We propose a Markovian quantum master equation that can describe the Fano effect directly, by assuming a standard cavity quantum electrodynamics system.The framework allows us to generalize the Fano formula, applicable over the weak-and strong-coupling regimes with pure dephasing.A formulation of its emission spectrum is also given in a consistent manner.We then find that the interference responsible for the Fano effect is robust against pure dephasing.This is counterintuitive because the impact of interference is, in general, severely reduced by decoherence processes.Our approach thus provides a basis for theoretical treatments of the Fano effect and insights into the quantum interference in open quantum systems.
A strong optical nonlinearity arises when coherent light is scattered by a semiconductor quantum dot coupled to a nanophotonic waveguide. We exploit the Fano effect in such a waveguide to control the phase of the quantum interference underpinning the nonlinearity, experimentally demonstrating a tunable quantum optical filter which converts a coherent input state into either a bunched or an antibunched nonclassical output state. We show theoretically that the generation of nonclassical light is predicated on the formation of a two-photon bound state due to the interaction of the input coherent state with the quantum dot. Our model demonstrates that the tunable photon statistics arise from the dependence of the sign of two-photon interference (either constructive or destructive) on the detuning of the input relative to the Fano resonance.
Interference-induced photon antibunching is investigated for a three-level system coupled to a cavity mode, in which the level scheme is of a lambda type. One of the transitions is weakly coupled to the cavity mode while the other is driven by a control field. Without the control field, i.e. , in the conventional cavity quantum electrodynamics (QED) scheme in the weak coupling regime, photon antibunching can be achieved by carefully choosing the coupling strength and the detuning. This condition can be alleviated by tuning the strength and the frequency of the control field. The condition for the optimal control field that yields photon blockade is derived, and the effects of changing various parameters are investigated. For a given a set of dissipation rates, the atom-cavity coupling strength g needs to be higher than a certain threshold value, although the whole system still remains in the weak coupling regime. A numerical method for finding the optimal parameter regime is proposed.