Temperature-driven false-vacuum decay in coherently coupled Bose superfluids

Year: 2026

Authors: Sivasankar P.M., Dalfovo F., Recati A., Roy A.

Autors Affiliation: Indian Inst Technol Mandi, Sch Phys Sci, Mandi 175075, Himachal Prades, India; Univ Trento, Pitaevskii BEC Ctr, CNR INO, I-38123 Trento, Italy; Univ Trento, Dipartimento Fis, I-38123 Trento, Italy; INFN, Trento Inst Fundamental Phys & Applicat, I-38123 Trento, Italy.

Abstract: The relaxation of a quantum field from a metastable state (false vacuum) to a stable one (true vacuum), also known as false-vacuum decay, is a fundamental problem in quantum field theory and cosmology. We study this phenomenon using a two-dimensional interacting and coherently coupled Bose-Bose mixture, a platform that has already been employed experimentally to investigate false-vacuum decay in one dimension. In such a mixture, it is possible to define an effective magnetization that acts as a quantum field variable. Using the stochastic projected Gross-Pitaevskii equation (SPGPE), we prepare thermal equilibrium states in the false vacuum and extract decay rates from the magnetization dynamics. The decay rates show an exponential dependence on temperature, in line with the thermal theory of instantons. Since the SPGPE is based on complex scalar fields, it also allows us to explore the behavior of the phase, which turns out to become dynamic during decay. Our results confirm the SPGPE as an effective tool for studying coupled magnetization and phase dynamics and the associated instanton physics in ultracold quantum gases.

Journal/Review: PHYSICAL REVIEW A

Volume: 113 (6)      Pages from: 63323-1  to: 63323-9

More Information: We thank Subhadeep Patra and Sunilkumar Venkateshappa for several insightful discussions. P.M.S. gratefully acknowledges M. Obasho for constructive discussions of GPU-based implementation. A. Roy acknowledges support from the Science and Engineering Research Board, Department of Science and Technology, Government of India, under Project No. SRG/2022/000057 and IIT Mandi seed-grant funds under Project No. IITM/SG/AR/87. A. Roy acknowledges the National Supercomputing Mission for providing computing resources of PARAM Hima laya at IIT Mandi, which is implemented by C-DAC and supported by the Ministry of Electronics and Information Technology and Department of Science and Technology, Government of India. F.D. and A. Recati thank the Provincia autonoma di Trento for support. A. Recati acknowledges the Italian National Institute for Nuclear Physics for support through the RELAQS project. This work was funded by the European Union under Grant No. 101199451-QFIELBS. Views and opinions expressed are those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the European Research Council Executive Agency can be held responsible for them.
KeyWords: Quantum; Dynamics; Fate
DOI: 10.1103/w5sj-lrsx