Quantum Limits to Linewidth Narrowing in Single- and Few-Atom Cavity Electromagnetically Induced Transparency

Abstract

Electromagnetically induced transparency (EIT) in cavities can narrow the transmission resonance below the empty-cavity linewidth. We investigate the limits of this narrowing from a single emitter to the few-atom regime. Using a Lindblad master equation for $N_{at}$ identical three-level atoms coupled to a cavity mode, driven by coherent probe and control fields, we compute the full width at half maximum (FWHM) of the transparency feature. In the strictly low-excitation limit, we derive an analytical cubic polynomial that captures the narrowing and recovers the known linear-response scaling. For finite probe powers, the achievable linewidth faces a quantum bound on the minimum achievable linewidth. Contrasting our model with a semiclassical approximation, we show this limitation arises from the unavoidable excitation of higher-order multiphoton states. Their intrinsically larger decay rates destroy the ideal single-excitation EIT dark state. Increasing $N_{at}$ enhances collective cooperativity, creating a multiphoton blockade that suppresses these detrimental excitations and yields a stepwise reduction of the minimum FWHM. Our results provide analytical boundaries for cavity-EIT linewidth control, guiding the optimization of narrowband filters and highly coherent light-matter interfaces.

arXiv comment13 pages, 7 figures

References in corpus (17)

• QuTiP: An open-source Python framework for the dynamics of open quantum systems
• Storage of light in atomic vapor
• Cavity-based quantum networks with single atoms and optical photons
• A Single-Atom Quantum Memory
• Electromagnetically induced transparency on a single artificial atom
• Electromagnetically induced transparency with single atoms in a cavity
• Ground state laser cooling using electromagnetically induced transparency
• Experimental demonstration of ground state laser cooling with electromagnetically induced transparency
• Photon-photon interactions in cavity electromagnetically induced transparency
• EIT ground-state cooling of long ion strings
• Optical control of the refractive index of a single atom
• Electromagnetically Induced Transparency from a Single Atom in Free Space
• High-performance cavity-enhanced quantum memory with warm atomic cell
• Many-body cavity quantum electrodynamics with driven inhomogeneous emitters
• Realization of cavity linewidth narrowing via interacting dark resonances in a tripod-type electromagnetically induced transparency system
• Tweezer-assisted subwavelength positioning of atomic arrays in an optical cavity
• Sensitivity of electromagnetically induced transparency to light-mediated interactions