Unmasking the microscopic fingerprint in finite-temperature features of a one-dimensional Bose gas
A team of researchers from the UPC in Barcelona and the EPFL in Lausanne have built a new theory to explain finite-temperature properties in terms of microscopic excitations of bosons in one dimension.
Jan 19, 2023
An ensemble of particles moving along one spatial dimension looks deceivingly straightforward, but it is actually an extremely complex system due to the intricate interplay of quantum effects, interparticle collisions and thermal motion.
Understanding the thermal properties of a set of bosonic particles with pairwise repulsive contact interactions is fundamental to basic research and the development of emerging quantum technologies, quantum computers and innovative engineering materials including high-critical-temperature superconductors. One-dimensional Bose systems have been experimentally realised since 2004 with ultracold atomic gases.
A problem that remained unsolved until now was a global understanding of the effects of microscopic excitations on the temperature dependence of thermodynamic properties for any interaction.
In a study published in SciPost Physics, researchers Giulia De Rosi, Grigori Astrakharchik and Jordi Boronat at the Universitat Politècnica de Catalunya - BarcelonaTech (UPC) and Riccardo Rota at the École Polytechnique Fédérale de Lausanne (EPFL) demonstrated that the novel hole anomaly (i.e. the peak in the temperature dependence of the specific heat) is due to the thermal occupation of states located below the hole branch in the excitation spectrum. At the anomaly temperature, there is the breakdown of the quasiparticle description of excitations holding at lower temperatures. These features of the hole anomaly around the critical temperature are also shared by certain phase transitions and crossovers in one dimension.
The study will foster further investigations aimed at characterising collisions in one-dimensional Bose gases and providing new methods for the measurement of temperature in ultracold atom experiments. The new hole anomaly may be used as a quantum simulator of other anomalies in atomic, solid-state, electronic and spin systems.
