Quantum Action of the Josephson Dynamics

Year: 2025

Authors: Vianello C., Salvatore S., Salasnich L.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; INFN Sez Padova, Via Marzolo 8, I-35131 Padua, Italy; Univ Padua, Padua QTech Ctr, Via Gradenigo 6-A, I-35131 Padua, Italy; CNR INO, Via Carrara 1, I-50019 Sesto Fiorentino, Italy.

Abstract: We study the beyond-mean-field Josephson dynamics of the relative phase between two coupled macroscopic quantum systems. Using a covariant background field method, we derive the one-loop only-phase quantum effective action and the corresponding equation of motion for the quantum average of the phase. These analytical results are benchmarked against the exact quantum dynamics of the two-site Bose-Hubbard model, demonstrating a relevant improvement over the standard mean-field predictions across a wide range of interaction strengths.

Journal/Review: INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS

Volume: 64 (11)      Pages from: 315-1  to: 315-16

More Information: C.V. and L.S. are supported by Iniziativa Specifica Quantum of INFN and by the Project Frontiere Quantistiche (Dipartimenti di Eccellenza) of the Italian Ministry of University and Research (MUR). L.S. is partially supported by funds of the European Union-Next Generation EU: European Quantum Flagship Project PASQuanS2, National Center for HPC, Big Data and Quantum Computing [Spoke 10: Quantum Computing]. L.S. also acknowledges the PRIN Project Quantum Atomic Mixtures: Droplets, Topological Structures, and Vortices of MUR.
KeyWords: Josephson oscillations; Quantum effective action; Bosonic Josephson junctions
DOI: 10.1007/s10773-025-06186-0