Theory Seminar: Dissipation-induced Bipolaron Localization
Mattia Moroder, LMU
Theory Seminar at MPQ, lecture hall
Wednesday, November 9th, 2022, 11:00am (MEZ)
Recent advances in numerical methods significantly pushed forward the understanding of electrons coupled to quantized lattice vibrations. At this stage,it becomes increasingly important to also account for effects of physically inevitable environments.
In this article , we study the transport properties of the Hubbard-Holstein Hamiltonian that models a large class of materials characterized by strong electron-phonon coupling, in contact to a dissipative environment. Even in the one-dimensional and isolated case, simulating the quantum dynamics of such a system with high accuracy is very challenging due to the infinite-dimensionality of the phononic Hilbert spaces. For this reason, the effects of dissipation on the conductance properties of such systems have not been investigated systematically so far. We close this gap by combining the non-Markovian (HOPS)  method and the Markovian (QJ)  method with the newly introduced (PP-DMRG) , creating powerful tensor network methods for dissipative quantum many-body systems. Investigating their numerical properties, we find a significant speedup up to a factor ∼ 30 compared to conventional tensor-network techniques. We apply these methods to study dissipative quenches, aiming for an indepth understanding of the formation, stability, and quasi-particle properties of bipolarons. Surprisingly, our results show that in the metallic phase, dissipation localizes the bipolarons, which we interpret as an instance of the indirect quantum Zeno effect. However, the bipolaronic binding energy remains mainly unaffected, even in the presence of strong dissipation, exhibiting remarkable bipolaron stability. These findings shed new light on the problem of designing real materials exhibiting phonon-mediated high-TC superconductivity.
 Mattia Moroder et al. Metallicity in the Dissipative Hubbard-Holstein Model:Markovian and Non-Markovian Tensor-Network Methods for Open Quantum Many-Body Systems. 2022. doi: 10.48550/ARXIV.2207.08243. url:https://arxiv.org/abs/2207.08243.
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