Physics

Mathematics

Quantum phase transition

Biology

Statistics

Ultracold atom

Magnet

Quantum fluctuation

Paleontology

Atomic physics

Superfluidity

Condensed matter physics

Context (archaeology)

Quantum mechanics

Realization (probability)

Levitation

Quantum phases

Excitation

Quantum

Physical Review Letters

Self-bound quantum droplets are a newly discovered phase in the context of ultracold atoms. In this Letter, we report their experimental realization following the original proposal by Petrov [Phys. Rev. Lett. 115, 155302 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.155302], using an attractive bosonic mixture. In this system, spherical droplets form due to the balance of competing attractive and repulsive forces, provided by the mean-field energy close to the collapse threshold and the first-order correction due to quantum fluctuations. Thanks to an optical levitating potential with negligible residual confinement, we observe self-bound droplets in free space, and we characterize the conditions for their formation as well as their size and composition. This work sets the stage for future studies on quantum droplets, from the measurement of their peculiar excitation spectrum to the exploration of their superfluid nature.

Self-Bound Quantum Droplets of Atomic Mixtures in Free Space