Speaker
Description
We study the physics of an impurity confined in a lattice coupled to a Bose-Hubbard bath at zero temperature. Within the Quantum Gutzwiller formalism [1], we develop a beyond-Fröhlich model of the bath-impurity interaction. Results for the properties of the polaronic quasiparticle due to the dressing of the impurity by quantum fluctuations of the bath are presented throughout the entire phase diagram, focusing on the effect of the Mott-insulator to superfluid quantum phase transition [2]. In the case of strong bath-impurity interaction we develop a new diagrammatic approach based on the quantum Gutzwiller Hamiltonian and the results for the ground state energy is benchmarked via Quantum Monte-Carlo (QMC) calculations [3]. We characterise the modification of the impurity properties due to the presence of the Mott-Superfluid phase transition, and show that the polaron energy shows finite scaling behaviour [4]. Eventually we mention how to realise the dephasing model by coupling a fixed impurity to a Bose-Hubbard model and emphisize the role of an impurity as an unambiguous probe of the quantum criticality of the manybody environment [5].
[1] F. Caleffi, M. Capone, C. Menotti, I. Carusotto, A. Recati, Phys. Rev. Research 2, 033276 (2020).
[2] V. Colussi, F. Caleffi, C. Menotti, A. Recati, Phys. Rev. Lett. 130, 173002 (2023).
[3] R. Alhyder, V. E. Colussi, M. Čufar, J. Brand, A. Recati, G. M. Bruun, SciPost Phys. 19, 002 (2025).
[4] M. Čufar, R. Alhyder, C. J. Bradly, V. E. Colussi, G. M. Bruun, J. Brand, A. Recati, to be submitted.
[5] F. Caleffi, M. Capone, I. de Vega and A. Recati, New J. Phys. 23 033018 (2021)