Scientists at Harvard have achieved a major breakthrough in the study of quantum matter by successfully realizing a Laughlin state using ultracold atoms manipulated by lasers. Laughlin states are exotic forms of matter that were first theorized during the 1980s and are characterized by their appearance in two-dimensional materials under extremely cold conditions and strong magnetic fields.
In a Laughlin state, electrons form a peculiar quantum liquid, where each electron dances around its fellow electrons while avoiding them as much as possible. This creates a unique behavior that researchers have been keen to explore further. Exciting this quantum liquid generates collective states that are associated with fictitious particles known as “anyons.” Anyons carry a fractional charge, which is a fraction of the elementary charge, and they defy the traditional classification of particles as bosons or fermions.
The challenge for physicists has been to find a way to realize Laughlin states in systems other than solid-state materials. The necessary ingredients, such as the 2D nature of the system, the intense magnetic field, and strong particle correlations, have proven very challenging to reproduce.
However, an international team of researchers led by Markus Greiner at Harvard has managed to achieve this feat using ultracold neutral atoms manipulated by lasers. The experiment involved trapping a few atoms in an optical box and implementing the required ingredients for the creation of the exotic Laughlin state, including a strong synthetic magnetic field and strong repulsive interactions among the atoms.
To study the properties of the Laughlin state, the researchers utilized a powerful quantum-gas microscope to image the atoms individually. Through this imaging technique, they were able to observe the unique “dance” of the particles as they orbited around each other, confirming the fractional nature of the atomic Laughlin state.
This groundbreaking achievement opens up new opportunities for further exploration of Laughlin states and related states, such as the Moore-Read state, in quantum simulators. The ability to create, image, and manipulate anyons under a quantum-gas microscope offers exciting possibilities for harnessing their unique properties in laboratory settings.
The study, titled “Realization of a fractional quantum Hall state with ultracold atoms,” was published in the journal Nature and was conducted by Julian Léonard, Sooshin Kim, Joyce Kwan, Perrin Segura, Fabian Grusdt, Cécile Repellin, Nathan Goldman, and Markus Greiner. This milestone achievement marks a significant advancement in our understanding and manipulation of quantum matter.