A joint theoretical study by the University of Innsbruck and Zhejiang University has uncovered the microscopic origin of a striking quantum phenomenon: a periodically driven gas of ultracold atoms that simply refuses to heat up, defying classical expectations.

Push a swing repeatedly in rhythm, and it swings higher and higher, absorbing more and more energy. A quantum gas, however, can behave very differently. Under periodic kicks, quantum interference can freeze energy absorption entirely, a phenomenon known as dynamical localization. Whether this survives when particles interact with each other has been a long-standing open question. A 2025 experiment by the research group of Hanns-Christoph Nägerl at the Department of Experimental Physics confirmed that it can. But the microscopic reasons remained until now unclear.

A new theoretical study by Prof. Lei Ying’s team at Zhejiang University, in collaboration with Prof. Hanns-Christoph Nägerl’s group at the University of Innsbruck, published in Physical Review Letters, provides the missing explanation. The team developed a mathematical framework that transforms the complex-driven many-body problem into a tractable lattice model. This reveals that interactions introduce a universal power-law structure that reshapes localization—and ultimately drives its breakdown at intermediate interaction strengths.