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Transition behavior in extended two-level systems with a band-touching point.
Amirreza Hemmatzade1, Davoud Nasr Esfahani2,3, Mohammad Sadegh Vaezi4,5
1Pasargad Institute for Advanced Innovative Solutions (PIAIS), Tehran, 19395-5531, Iran.
Scientific Reports
|October 9, 2025
Summary
Researchers analyzed transition dynamics in gapless systems using fidelity susceptibility. They found conditions for adiabatic evolution, challenging the notion that these systems are always nonadiabatic.
Area of Science:
- Condensed Matter Physics
- Quantum Dynamics
Background:
- Quadratic terms in energy dispersion influence transition dynamics in graphene-like models.
- Fidelity susceptibility reveals dominant contributions to nonadiabatic transitions near band-touching points.
Purpose of the Study:
- Extend transition dynamics analysis to general gapless systems.
- Identify key Hamiltonian terms driving transitions near band-touching points.
- Investigate conditions for adiabatic evolution in gapless systems.
Main Methods:
- Analysis of fidelity susceptibility in gapless systems.
- Derivation of upper bounds for adiabaticity.
- Establishment of conditions for adiabatic evolution in effective two-level systems.
Main Results:
- Identified key Hamiltonian terms driving transitions near band-touching points.
- Derived upper bounds for adiabaticity in certain gapless systems.
- Found that transition probabilities reflect an exponential form related to adiabaticity bounds.
Conclusions:
- Gapless systems can exhibit adiabatic evolution under specific conditions.
- The study provides a framework for understanding and realizing gapless Hamiltonians.
- Findings challenge the common belief of inherent nonadiabaticity in gapless systems.
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