Near-adiabatic parameter changes in correlated systems: Influence of the ramp protocol on the excitation energy - Condensed Matter > Strongly Correlated ElectronsReport as inadecuate




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Abstract: We study the excitation energy for slow changes of the hopping parameter inthe Falicov-Kimball model with nonequilibrium dynamical mean-field theory. Theexcitation energy vanishes algebraically for long ramp times with an exponentthat depends on whether the ramp takes place within the metallic phase, withinthe insulating phase, or across the Mott transition line. For ramps withinmetallic or insulating phase the exponents are in agreement with a perturbativeanalysis for small ramps. The perturbative expression quite generally showsthat the exponent depends explicitly on the spectrum of the system in theinitial state and on the smoothness of the ramp protocol. This explains thequalitatively different behavior of gapless e.g., metallic and gapped e.g.,Mott insulating systems. For gapped systems the asymptotic behavior of theexcitation energy depends only on the ramp protocol and its decay becomesfaster for smoother ramps. For gapless systems and sufficiently smooth rampsthe asymptotics are ramp-independent and depend only on the intrinsic spectrumof the system. However, the intrinsic behavior is unobservable if the ramp isnot smooth enough. This is relevant for ramps to small interaction in thefermionic Hubbard model, where the intrinsic cubic fall-off of the excitationenergy cannot be observed for a linear ramp due to its kinks at the beginningand the end.



Author: Martin Eckstein, Marcus Kollar

Source: https://arxiv.org/







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