Physics:Quantum Berry phase
Quantum Berry phase is a geometric phase acquired by a quantum state when the parameters of a system are changed slowly around a closed path. Unlike an ordinary dynamical phase, which depends on energy and elapsed time, the Berry phase depends on the geometry of the path traced in parameter space.[1]
The idea was introduced by Michael Berry in 1984 and quickly became a unifying concept across quantum mechanics, condensed matter physics, optics, molecular physics, and quantum information. It shows that the history of a quantum state can leave a measurable phase imprint even when the system returns to its original physical configuration.
Geometric phase
In an adiabatic cycle, a quantum system remains in an instantaneous eigenstate while its Hamiltonian changes slowly. When the parameters return to their starting values, the state may acquire a phase determined by the curvature of the path in parameter space.
This phase can affect interference experiments and observable quantities. It is therefore not merely a mathematical convention, but part of the measurable structure of quantum evolution.
Uses
Berry phase appears in the Aharonov-Bohm effect, molecular conical intersections, polarization optics, topological phases of matter, and the quantum Hall effect. In modern materials it helps describe band topology and robust edge behavior.
The concept is closely related to gauge structure, parallel transport, and the topology of quantum states.
See also
- Physics:Quantum Time evolution
- Physics:Quantum Adiabatic theorem
- Physics:Quantum Aharonov-Bohm effect
- Physics:Quantum Topological phases of matter
References
- ↑ "Berry phase". Wikipedia. https://en.wikipedia.org/wiki/Berry_phase.
Source attribution: Physics:Quantum Berry phase