By using worldline and diagrammatic quantum Monte Carlo techniques, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of a quantum system of N spins antiferromagnetically interacting with each other, with strength J, and coupled to a common bath of bosonic oscillators, with strength α. We show that, in the Ohmic regime, a Beretzinski-Thouless-Kosterlitz quantum phase transition occurs. While for J=0 the critical value of α decreases asymptotically with 1/N by increasing N, for nonvanishing J it turns out to be practically independent on N, allowing to identify a finite range of values of α where spin phase coherence is preserved also for large N. Then, by using matrix product state simulations, and the Mori formalism and the variational approach à la Feynman jointly, we unveil the features of the relaxation, that, in particular, exhibits a nonmonotonic dependence on the temperature reminiscent of the Kondo effect. For the observed quantum phase transition we also establish a criterion analogous to that of the metal-insulator transition in solids.

Quantum phase transition of many interacting spins coupled to a bosonic bath: Static and dynamical properties / De Filippis, G.; De Candia, A.; Mishchenko, A. S.; Cangemi, L. M.; Nocera, A.; Mishchenko, P. A.; Sassetti, M.; Fazio, R.; Nagaosa, N.; Cataudella, V.. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 104:6(2021). [10.1103/PhysRevB.104.L060410]

Quantum phase transition of many interacting spins coupled to a bosonic bath: Static and dynamical properties

De Filippis G.;De Candia A.;Cangemi L. M.;Sassetti M.;Fazio R.;Cataudella V.
2021

Abstract

By using worldline and diagrammatic quantum Monte Carlo techniques, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of a quantum system of N spins antiferromagnetically interacting with each other, with strength J, and coupled to a common bath of bosonic oscillators, with strength α. We show that, in the Ohmic regime, a Beretzinski-Thouless-Kosterlitz quantum phase transition occurs. While for J=0 the critical value of α decreases asymptotically with 1/N by increasing N, for nonvanishing J it turns out to be practically independent on N, allowing to identify a finite range of values of α where spin phase coherence is preserved also for large N. Then, by using matrix product state simulations, and the Mori formalism and the variational approach à la Feynman jointly, we unveil the features of the relaxation, that, in particular, exhibits a nonmonotonic dependence on the temperature reminiscent of the Kondo effect. For the observed quantum phase transition we also establish a criterion analogous to that of the metal-insulator transition in solids.
2021
Quantum phase transition of many interacting spins coupled to a bosonic bath: Static and dynamical properties / De Filippis, G.; De Candia, A.; Mishchenko, A. S.; Cangemi, L. M.; Nocera, A.; Mishchenko, P. A.; Sassetti, M.; Fazio, R.; Nagaosa, N.; Cataudella, V.. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 104:6(2021). [10.1103/PhysRevB.104.L060410]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/882340
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