Details

Autor(en) / Beteiligte

• Ferioli, Giovanni
• Glicenstein, Antoine
• Ferrier-Barbut, Igor
• Browaeys, Antoine

Titel

A non-equilibrium superradiant phase transition in free space

Ist Teil von

• Nature physics, 2023-09, Vol.19 (9), p.1345-1349

Ort / Verlag

London: Nature Publishing Group

Erscheinungsjahr

2023

Link zum Volltext

Quelle

Nature Journals Online

Beschreibungen/Notizen

• A class of systems exists in which dissipation, external drive and interactions compete and give rise to non-equilibrium phases that would not exist without the drive. There, phase transitions could occur without the breaking of any symmetry, yet with a local order parameter—in contrast to the Landau theory of phase transitions at equilibrium. One of the simplest driven–dissipative quantum systems consists of two-level atoms enclosed in a volume smaller than the wavelength of the atomic transition cubed, driven by a light field. The competition between collective coupling of the atoms to the driving field and their cooperative decay should lead to a transition between a phase where all the atomic dipoles are phase-locked and a phase governed by superradiant spontaneous emission. Here, we realize this model using a pencil-shaped cloud of laser-cooled atoms in free space, optically excited along its main axis, and observe the predicted phases. Our demonstration is promising in view of obtaining free-space superradiant lasers or observing new types of time crystal.Some driven systems sustain non-equilibrium phases in which phase transitions occur without symmetry breaking. The use of a laser-cooled atomic cloud confined in a pencil beam now allows the demonstration of such a system.