Quantum density anomaly in optically trapped ultracold gases

Abstract

Water, the substance of life, is known for its myriad of anomalous properties, whose origins are still the subject of intense debates. In order to provide a different insight into this problem, we show how its density anomaly can be reproduced using a quantum simulator. In particular, we demonstrate that the Bose-Hubbard model, a paradigm system in quantum mechanics, exhibits an increase in density with temperature at fixed pressure in the regular fluid regime and in the superfluid phase. We propose that the mechanism underlying the anomalies is related to zero-point entropies and ground-state phase transitions. A connection with the typical experimental scales and setups including confinement effects is also addressed. In this scenario, such finding opens a pathway for theoretical and experimental studies of waterlike anomalies in the area of ultracold quantum gases.