We study the nonequilibrium steady-state of a fully-coupled network of $N$ quantum harmonic oscillators, interacting with two thermal reservoirs. Given the long-range nature of the couplings, we consider two setups: one in which the number of particles coupled to the baths is fixed (intensive coupling) and one in which it is proportional to the size $N$ (extensive coupling). In both cases, we compute analytically the heat fluxes and the kinetic temperature distributions using the nonequilibrium Green's function approach, both in the classical and quantum regimes. In the large $N$ limit, we derive the asymptotic expressions of both quantities as a function of $N$ and the temperature difference between the baths. We discuss a peculiar feature of the model, namely that the bulk temperature vanishes in the thermodynamic limit, due to a decoupling of the dynamics of the inner part of the system from the baths. At variance with usual cases, this implies that the steady state depends on the initial state of the particles in the bulk. We also show that quantum effects are relevant only below a characteristic temperature that vanishes as $1/N$. In the quantum low-temperature regime the energy flux is proportional to the universal quantum of thermal conductance.
Cited by 2
Authors / Affiliations: mappings to Contributors and OrganizationsSee all Organizations.
- 1 Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies [SISSA]
- 2 INFN Sezione di Trieste / INFN Trieste
- 3 Istituto Nazionale di Fisica Nucleare / National Institute for Nuclear Physics [INFN]
- 4 Istituto dei sistemi complessi / Institute for Complex Systems [ISC]
- 5 Università degli Studi di Trieste / University of Trieste [UNITS]
- 6 Istituto di Struttura della Materia / Institute of Structure of Matter [CNR-ISM]
- Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR) (through Organization: Ministero dell'Istruzione, dell'Università e della Ricerca / Ministry of Education, Universities and Research [MIUR])