First ever realization of Laughlin’s state

The ultracold atoms manipulated by the laser realized a Laughlin state, a strange quantum fluid in which each atom dances around its congeners. Credit: Nathan Goldman

The discovery of quantum hall effects during the 1980s revealed new forms of matter called “Laughlin states,” named after the American Nobel laureate who successfully distinguished them theoretically.

These strange states appear uniquely in 2D materials, under extremely cold conditions, and when subjected to an extremely strong magnetic field. In Laughlin’s case, the electrons form an unusual liquid, in which each electron dances around its congeners while avoiding them as much as possible.

Excitation of such a quantum fluid generates collective states that physicists associate with phantom particles, whose properties are fundamentally different from electrons: these “ions” carry a fractional charge (part of the elementary charge) and surprisingly defy the standard classification of particles in terms of bosons or fermions.

For many years, physicists have explored the possibility of realizing Laughlin states in other types of systems than those provided by solid-state materials, in light of further analysis of their special properties. However, the required components (the two-dimensional nature of the system, intense magnetic field, and strong inter-particle correlations) have proven to be very challenging.

Writing natureAn international team gathered around the experimental group of Marcus Grenier at Harvard reported the first realization of the Laughlin state using very cold neutral atoms manipulated by lasers.

The experiment consists of trapping a few atoms in an optical box, and in implementing the ingredients required to create this strange state: a strong synthetic magnetic field and strong, repulsive interactions between the atoms.

In their article, the authors reveal the defining properties of the Laughlin state by imaging atoms one by one through a powerful quantum gas microscope. They show the strange “dance” of particles, which orbit each other, as well as the partial nature of the realized atomic Laughlin state.

This milestone opens the door to a vast new field for exploring Laughlin states and their cousins ​​(for example, the so-called Moore-Read state) in quantum simulations. The possibility of creating, imaging and manipulating any gems under a quantum gas microscope is particularly attractive, in light of the exploitation of their unique properties in the laboratory.

Reference: “Achieving the Fractional Quantum Hall State with Extremely Cold Atoms” By Julian Leonard, Suchin Kim, Joyce Cowan, Perrin Segura, Fabian Grosdt, Cecil Replin, Nathan Goldman and Marcus Grenier, June 21, 2023, Available Here. nature.
DOI: 10.1038/s41586-023-06122-4