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Dynamical preparation of Floquet Chern insulators
Luca D'Alessio1,2, Marcos Rigol1
1Department of Physics, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.
Nature Communications
|October 2, 2015
Summary
Researchers explored driving topological insulators using electric fields. They found topological invariants can change in systems with boundaries, enabling experimental preparation of topological states and control of edge currents.
Area of Science:
- Condensed matter physics
- Quantum mechanics
- Materials science
Background:
- Topological insulators possess unique properties with potential applications.
- Periodic driving offers a route to engineer non-trivial topological states from trivial ones.
Purpose of the Study:
- Investigate the dynamics of topological states under periodic driving.
- Examine the conservation and change of topological invariants in driven systems.
Main Methods:
- Exact analytical study of time evolution.
- Analysis of a graphene-like system under circularly polarized electric fields.
- Investigation of both infinite and finite (boundary) systems.
Main Results:
- The Chern number is conserved under unitary evolution in infinite systems.
- A defined topological invariant (Bott index) can change in systems with boundaries.
- Chirality of edge currents is controllable by adjusting system filling.
Conclusions:
- It is experimentally feasible to prepare topological states from non-topological ones.
- Periodic driving provides a mechanism to control topological properties and edge currents.
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