scholarly journals Improved Dyson series expansion for steady-state quantum transport beyond the weak coupling limit: Divergences and resolution

2014 ◽  
Vol 141 (19) ◽  
pp. 194101 ◽  
Author(s):  
Juzar Thingna ◽  
Hangbo Zhou ◽  
Jian-Sheng Wang
Keyword(s):  
Steady State ◽  
Series Expansion ◽  
Quantum Transport ◽  
Weak Coupling ◽  
Weak Coupling Limit ◽  
Dyson Series

scholarly journals Stationary states of weak coupling limit-type Markov generators and quantum transport models

2020 ◽  
Vol 23 (01) ◽  
pp. 2050003
Author(s):  
A. Hernández-Cervantes ◽  
R. Quezada
Keyword(s):  
Quantum Transport ◽  
Weak Coupling ◽  
Energy Transport ◽  
Transport Model ◽  
Weak Coupling Limit ◽  
Stationary States ◽  
Transport Models ◽  
Markov Generator ◽  
Kraus Operators ◽  
Creation Operators

We prove that every stationary state in the annihilator of all Kraus operators of a weak coupling limit-type Markov generator consists of two pieces, one of them supported on the interaction-free subspace and the second one on its orthogonal complement. In particular, we apply the previous result to describe in detail the structure of a slightly modified quantum transport model due to Arefeva et al. (modified AKV’s model) studied first in [J. C. García et al., Entangled and dark stationary states of excitation energy transport models in many-particles systems and photosynthesis, Infin. Dimens. Anal. Quantum Probab. Relat. Top. 21(3) (2018), Article ID: 1850018, p. 21, doi:10.1142/S0219025718500182], in terms of generalized annihilation and creation operators.

scholarly journals On the Lyapunov–Perron reducible Markovian Master Equation

2021 ◽  
Author(s):  
Krzysztof Szczygielski
Keyword(s):  
Steady State ◽  
Master Equation ◽  
Quantum System ◽  
Projection Operator ◽  
Weak Coupling ◽  
Open Quantum System ◽  
Weak Coupling Limit ◽  
Periodic Case ◽  
Stability Of Solutions ◽  
Projection Operator Techniques

We consider an open quantum system in [Formula: see text] governed by quasiperiodic Hamiltonian with rationally independent frequencies and under the assumption of Lyapunov–Perron reducibility of the associated Schrödinger equation. We construct the Markovian Master Equation and the resulting CP-divisible evolution in the weak coupling limit regime, generalizing our previous results from the periodic case. The analysis is conducted with the application of projection operator techniques and concluded with some results regarding stability of solutions and existence of quasiperiodic global steady state.

scholarly journals An obstacle to sub-AdS holography for SYK-like models

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang ◽  
Yingfei Gu ◽  
Alexei Kitaev
Keyword(s):  
Lyapunov Exponent ◽  
Weak Coupling ◽  
Kinetic Coefficient ◽  
Weak Coupling Limit ◽  
Branching Time ◽  
Quasiparticle Lifetime

Abstract We argue that “stringy” effects in a putative gravity-dual picture for SYK-like models are related to the branching time, a kinetic coefficient defined in terms of the retarded kernel. A bound on the branching time is established assuming that the leading diagrams are ladders with thin rungs. Thus, such models are unlikely candidates for sub-AdS holography. In the weak coupling limit, we derive a relation between the branching time, the Lyapunov exponent, and the quasiparticle lifetime using two different approximations.

ENERGY BAND OVERLAPPING IN HIGH-Tc SUPERCONDUCTORS

1996 ◽  
Vol 10 (30) ◽  
pp. 1483-1490 ◽  
Author(s):  
M. MORENO ◽  
R. M. MÉNDEZ-MORENO ◽  
M. A. ORTIZ ◽  
S. OROZCO
Keyword(s):  
Weak Coupling ◽  
Cuprate Superconductors ◽  
Weak Coupling Limit ◽  
Band Model ◽  
Coupling Constant ◽  
High Tc Superconductors ◽  
Energy Bands ◽  
Effective Coupling ◽  
High Tc ◽  
Two Band Model

Multi-band superconductors are analyzed and the relevance of overlapping energy bands to the high-T c of these materials is studied. Within the BCS framework, a two band model with generalized Fermi surface topologies is developed. Values of the overlapped occupancy parameters for typical cuprate superconductors are obtained as a function of the ratio R and the effective coupling constant, λ, in the weak-coupling limit. The overlap scale is of the order or lower than the cutoff (Debye) energy. The typical behavior of the isotope effect is obtained. As these superconductors have transition temperatures above the phonon barrier, the results of this approach are important to the generic understanding of the high-T c superconducting mechanism.

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