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Geometric quantum noise of spin.
Alexander Shnirman1,2, Yuval Gefen3,4, Arijit Saha5
1Institut für Theorie der Kondensierten Materie and DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany.
Physical Review Letters
|May 16, 2015
Summary
Geometric phases influence quantum system dynamics, entering stochastic noise terms in dissipative environments. This study predicts and proposes observing quantum diffusion of magnetization on the Bloch sphere, governed by geometric phases.
Area of Science:
- Quantum mechanics
- Condensed matter physics
- Statistical mechanics
Background:
- Geometric phases impact system dynamics.
- Quantum systems in dissipative environments exhibit complex behavior.
- Understanding magnetization dynamics is crucial for nanomagnet and quantum dot applications.
Purpose of the Study:
- To investigate the influence of geometric phases on quantum systems in dissipative environments.
- To generalize effective action and equations of motion for SU(2) magnetization dynamics.
- To predict and propose experimental observation of geometric phase-governed quantum diffusion.
Main Methods:
- Utilizing Langevin equations with quantum noise to describe system dynamics.
- Generalizing the Ambegaokar-Eckern-Schön effective action for SU(2) symmetry.
- Analyzing the influence of geometric phases on Langevin forces (torques).
Main Results:
- Geometric phases are shown to enter the stochastic noise terms of the Langevin equation.
- The generalized semiclassical equations of motion reveal strong influence of geometric phase on Langevin forces.
- Low-temperature quantum diffusion of magnetization on the Bloch sphere is predicted.
Conclusions:
- Geometric phases play a significant role in the dynamics of quantum degrees of freedom in dissipative environments.
- The study provides a theoretical framework for understanding magnetization dynamics influenced by geometric phases.
- A protocol for experimental observation of geometric phase-governed quantum diffusion is proposed.
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