Many-body bound states and induced interactions of charged impurities in a bosonic bath

• Published in: Nature communications Vol. 14; no. 1; pp. 1647 - 11
• Main Authors: Astrakharchik, Grigory E., Ardila, Luis A. Peña, Jachymski, Krzysztof, Negretti, Antonio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.03.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/36/1125; 639/766/483/3926; Current carriers; Elementary excitations; Gases; Humanities and Social Sciences; Impurities; Investigations; Mathematical models; Monte Carlo simulation; multidisciplinary; Polarons; Quantum transport; Science; Science (multidisciplinary); Ultracold atoms
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-37153-0

Induced interactions and bound states of charge carriers immersed in a quantum medium are crucial for the investigation of quantum transport. Ultracold atom-ion systems can provide a convenient platform for studying this problem. Here, we investigate the static properties of one and two ionic impurities in a bosonic bath using quantum Monte Carlo methods. We identify three bipolaronic regimes depending on the strength of the atom-ion potential and the number of its two-body bound states: a perturbative regime resembling the situation of a pair of neutral impurities, a non-perturbative regime that loses the quasi-particle character of the former, and a many-body bound state regime that can arise only in the presence of a bound state in the two-body potential. We further reveal strong bath-induced interactions between the two ionic polarons. Our findings show that numerical simulations are indispensable for describing highly correlated impurity models. Polarons are quasi-particles that emerge when impurity particle is mixed with the low-energy excitations of a medium. Here the authors study the case of atom-ion quantum mixtures and identify three separate bipolaronic regimes which can arise depending on the interaction range and strength.