Quantum fluids and solids articles from across Nature Portfolio

Understanding phase transitions in open quantum systems is challenging. This work explores a driven-dissipative exciton polariton system undergoing an interaction-driven phase transition and reveals a relationship between the power-law decay of spatial coherence, the effective temperature of the system, and its coherent fraction, in surprising analogy to the conservative case.

Competition between different possible ground states of strongly correlated electron systems can lead to the emergence of mixed states called microemulsions. Now this phenomenon is reported at the melting transition of a Wigner crystal.

In classical hydrodynamics, Kelvin waves refer to helically vibrating normal modes. Experiments now show that quantum analogues of Kelvin waves can be excited in superfluid helium-4.

Counterflow superfluidity is a quantum phase in which two fluid components flow in opposite directions without resistance, cancelling out their overall combined motion. This phase has now been observed in an optical lattice system hosting Bose mixtures.

Electrons at extremely low density and temperature can crystallize into a solid known as a Wigner crystal. Optical spectroscopy now reveals how these crystals melt at higher densities via an intermediate phase, where crystalline and liquid regions coexist.

The collective behaviour of quantum gases strongly depends on the confining dimensionality. Its role in the emergence of a phase transition in a quantum gas of photons has now been explored using a new trapping technique, transitioning from 2D to 1D.

A superfluid is a macroscopic system with zero viscosity through which entropy is reversibly transported by waves. An unexpected transport phenomenon has now been observed between two superfluids, where irreversible entropy transport is enhanced by superfluidity.

90 years after Eugene Wigner predicted the formation of an ordered electron state, direct observations of a lattice of electrons in bilayer graphene not only verify the existence of a Wigner crystal but find unexpected physics.

Phonons do not carry spin or charge, but they can couple to an external magnetic field and cause a sizable transverse thermal gradient. Experiments suggest that phonon handedness is a widespread effect in magnetic insulators with impurities.

Graphene multistacks with four or five layers show the signature of correlated electronic states both in and out of a magnetic field.