In a recent study, researchers from the University of Waterloo and the University of Tennessee have explored the phenomenon of superfluidity in a specific quantum model, with potential implications for understanding and advancing quantum technologies in the energy sector. The team, comprising Muhammad Shaeer Moeed, Costanza Pennaforti, Adrian Del Maestro, and Roger G. Melko, has delved into the behavior of a one-dimensional spin-1/2 XY model with power-law interactions, a topic published in the prestigious journal Physical Review Letters.
The researchers focused on a quantum simulator using trapped ions, where effective spin-1/2 XY interactions can be engineered via laser-induced coupling between internal atomic states and collective phonon modes. In simple one-dimensional traps, these interactions decay as a power-law with distance, with a tunable exponent. The study examines the model near the phase transition at a critical value of the exponent, using the spin stiffness, or superfluid density, as a lens.
The team developed a stochastic series expansion quantum Monte Carlo simulation and a generalized winding number estimator to measure the superfluid density in the presence of power-law interactions. They tested these methods against exact diagonalization for small lattice sizes. The results show that conventional superfluidity in the one-dimensional XY model is enhanced in the long-range interacting regime. This enhancement is observed as a diverging superfluid density as the exponent approaches zero in the thermodynamic limit, consistent with linear spin-wave theory.
The researchers also defined a normalized superfluid density estimator that clearly distinguishes between short, medium, and long-range interacting regimes. This provides a novel quantum Monte Carlo probe of the critical value of the exponent. While the study is primarily theoretical, it offers insights into the behavior of quantum systems with long-range interactions, which could be relevant for developing advanced quantum technologies in the energy sector, such as quantum sensors and quantum communication devices.
This article is based on research available at arXiv.