In the realm of energy research, understanding the behavior of quantum systems can open doors to innovative technologies. Two researchers, M. Rodríguez Martín and T. A. Zaleski, from the University of Massachusetts Boston, have made strides in this area with their work on ultracold bosons in optical lattices.
Optical lattices are essentially crystal-like structures created by intersecting laser beams. They provide a pristine environment to study the quantum phases of matter. However, achieving the ultra-low entropy required for these studies is challenging. Current experiments operate at temperature-interaction ratios where zero-temperature theories may not be fully applicable.
The researchers have developed a finite-temperature extension of the quantum-rotor approach (QRA), a method used to study these quantum phases. The QRA is known for its analytical power and flexibility, but it has limitations at higher temperatures. To address this, the researchers first performed a resummation of winding-number contributions for temperatures up to about 0.2 in units of the interaction energy. Then, they developed an auxiliary-variable expansion that remains accurate even as temperatures increase further.
The result is a closed expression for the phase correlator, which describes how the quantum phases are related, that can be inserted into the standard QRA. This new approach maintains the method’s flexibility regarding lattice geometry and dimensionality. The researchers demonstrated that their finite-temperature QRA accurately reproduces the shrinkage of Mott lobes—regions of the phase diagram where particles are localized—as temperatures increase from zero to about 0.2 in units of the interaction energy. This is in agreement with both theoretical predictions and experimental data obtained from in-situ imaging.
The practical applications of this research for the energy sector are not immediate, but understanding and controlling quantum phases of matter could lead to advancements in quantum computing, sensing, and communication, which are increasingly relevant to energy systems. The researchers’ work provides a computationally light, analytical tool for studying strongly correlated lattice bosons, setting the stage for further upgrades required at higher temperatures. This research was published in the journal Physical Review A.
This article is based on research available at arXiv.