“The whole is greater than the sum of its parts.” Aristotle’s saying also holds true in many systems studied in quantum physics. Mikhail Lemeshko investigates how macroscopic quantum phenomena emerge in ensembles of atoms and molecules.

Most polyatomic systems in physics, chemistry, and biology are strongly correlated: their complex behavior cannot be deduced from the properties of their individual components. Despite considerable effort, understanding strongly correlated, many-body systems still present a formidable challenge. For instance, given a single atom of a certain kind, it is hard to predict whether the resulting bulk material will be solid, gaseous, or liquid, crystalline or amorphous, magnetic or non-magnetic, conductive or insulating. The Lemeshko group studies how many-particle quantum phenomena emerge in ensembles of atoms and molecules, and in so doing, answers questions such as: How many particles are sufficient for a given property to emerge? How does an external environment modify the properties of quantum systems? Their theoretical efforts aim to explain experiments on cold molecules and ultra-cold quantum gases, as well as predict novel, previously unobserved phenomena.