Long-Range Interactions and Symmetry Breaking in Quantum Gases through Optical Feedback

Area of Science:

• Atomic physics
• Quantum optics
• Condensed matter physics

Background:

• Bose-Einstein condensates (BECs) are quantum states of matter formed by cooling atoms to near absolute zero.
• Interactions between atoms in BECs can be manipulated using external fields, like lasers.
• Optical feedback systems, involving mirrors, can alter the behavior of light-matter interactions.

Purpose of the Study:

• To investigate the effects of single-mirror optical feedback on a quasi-two-dimensional atomic Bose-Einstein condensate.
• To explore the emergence of novel effective interactions and ground states in such a system.
• To determine the feasibility of observing these predicted phenomena in current experimental settings.

Main Methods:

• Theoretical modeling of a quasi-two-dimensional Bose-Einstein condensate.
• Inclusion of a near-resonant laser field with optical feedback from a planar mirror.
• Analysis of the resulting ground states and atomic configurations.

Main Results:

• The single-mirror optical feedback induces unusual effective interactions between ultracold atoms.
• A rich spectrum of ground states arises due to this induced interaction.
• The condensate can spontaneously contract into a one-dimensional chain of mesoscopic quantum droplets.

Conclusions:

• Single-mirror optical feedback offers a novel pathway to engineer interactions in atomic Bose-Einstein condensates.
• The formation of self-bound quantum droplets represents an exotic emergent phenomenon.
• Experimental observation of these quantum droplets is feasible with existing technology.