Correlated and Topological Matter with Cold Atoms
cold_atoms_smallExpected momentum distribution in the expansion of a spin-orbit coupled Bose-Einstein condensate.
In this MA, we will investigate and create topological and other novel forms of quantum correlated matter in cold atomic and molecular systems. Using probes of single particle measurement and measures of quantum entanglement, this activity may provide insight in the emergence and dynamics of exotic phases in real or artificial condensed-matter systems, some of which could lead to robust quantum information processing.

Condensed matter is replete with many-body effects, where interactions between innumerable particles determine the basic physics of the system. The discovery of a macroscopic phenomenon typically precedes its microscopic understanding, with prominent examples being the quantum Hall effect, high-temperature superconductivity and colossal magnetoresistance.

PFC researchers will attempt to turn this process around by using ultracold atomic systems to precisely engineer exotic classes of matter normally associated with condensed matter, from the bottom up. We are particularly interested in systems that acquire a novel kind of coherent quantum order that cannot be characterized by a local order parameter. This “topological order," epitomized by the fractional quantum Hall effect and certain kinds of frustrated magnetic ordering, can only be characterized by non-local topological properties and is related to highly entangled quantum many-body states that cannot be expressed as product states defined by local order parameters.

Topological phases are not apparent from microscopic condensed matter Hamiltonians, so the necessary conditions for the existence of topological order can only be determined through experiment.

Cold atoms offer new tools such as the control of interactions, the straightforward extraction of momentum distributions and correlations, and the near-perfect measurement of individual atomic spins and measures of entanglement, making them an ideal platform for the investigation of topological matter.

Apart from the fundamental aspects of topological emergence in nature, research in this area is of great interest to quantum information science (QIS) – an underlying theme for both JQI and the PFC. It is known that certain topological phases with non-Abelian quasiparticle statistics enable fault-tolerant quantum computation due to the protection guaranteed by the non-local nature of the underlying topological state, ensuring that no local environmental perturbation can lead to decoherence.