Spontaneous formation of a macroscopically extended coherent state

Abstract

It is a straightforward result of electromagnetism that dipole oscillators radiate more strongly when they are synchronized, and that if there are $N$ dipoles, the overall emitted intensity scales with $N^2$. In atomic physics, such an enhanced radiative property appears when coherence among two-level identical atoms is established, and is well-known as "superradiance" \cite{Dicke:1954aa}. In superfluorescence (SF), atomic coherence develops via a self-organisation process stemming from the common radiated field, starting from a incoherently prepared population inversion \cite{Bonifacio:1975aa}. First demonstrated in a gas \cite{Skribanowitz:1973} and later in condensed matter systems \cite{Florian:1984}, its potential is currently being investigated in the fields of ultranarrow linewidth laser development for fundamental tests in physics \cite{Meiser:2009,Meiser:2010,Bohnet:2012aa,Norcia:2016, Norcia:2018}, and for the development of devices enabling entangled multi-photon quantum light sources \cite{Raino:2018aa,Angerer:2018aa}. A barely developed aspect in superradiance is related to the properties of the dipole array that generates the pulsed radiation field. In this work we establish the experimental conditions for formation of a macroscopic dipole via superfluorescence, involving the remarkable number of $4\times 10^{12}$ atoms. Even though rapidly evolving in time, it represents a flexible test-bed in quantum optics. Self-driven atom dynamics, without the mediation of cavity QED nor quantum dots or quantum well structures, is observed in a cryogenically-cooled rare-earth doped material. We present clear evidence of a decay rate that is enhanced by more than 1-million times compared to that of independently emitting atoms. We thoroughly resolve the dynamics by directly measuring the intensity of the emitted radiation as a function of time.

References in corpus (16)

• Superfluorescence from Lead Halide Perovskite Quantum Dot Superlattices
• Prospects for a mHz-linewidth laser
• Coherence time of over a second in a telecom-compatible quantum memory storage material
• Steady-state superradiance with alkaline earth atoms
• Dicke Superradiance in Solids
• Superradiant Hybrid Quantum Devices
• Superabsorption of light via quantum engineering
• Giant Superfluorescent Bursts from a Semiconductor Magnetoplasma
• Coherent frequency up-conversion of microwaves to the optical telecommunications band in an Er:YSO crystal
• Axion Dark Matter Detection using Atomic Transitions
• Frequency measurements of superradiance from the strontium clock transition
• Microwave multimode memory with an Er${}^{3+}$:Y${}_2$SiO${}_5$ spin ensemble
• Cooperative Recombination of a Quantized High-Density Electron-Hole Plasma
• 3D Cavity quantum electrodynamics with a rare-earth spin ensemble
• Laser induced fluorescence for axion dark matter detection: a feasibility study in YLiF${}_4$:Er${}^{3+}$
• Light-harvesting with guide-slide superabsorbing condensed-matter nanostructures

Cited by in corpus (6)

• Cascade Superfluorescence in Er:YLF
• Intensity-correlated spiking infrared and ultraviolet emission from sodium vapors
• A Cascade Superradiance Model
• Collective spontaneous emission of two entangled atoms near an oscillating mirror
• Coherent response of inhomogeneously broadened and spatially localized emitter ensembles in waveguide QED
• Analytical and numerical studies of periodic superradiance