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Published on: January 19, 2018
Logarithmic current fluctuations in nonequilibrium quantum spin chains
T Antal1, P L Krapivsky, A Rákos
1Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts 02138, USA.
Summary
Researchers studied quantum spin chains at zero temperature, finding anomalous logarithmic growth in spin current variance for the XX model. This finding extends to the critical region of the XXZ model, offering insights into quantum transport phenomena.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Statistical Mechanics
Background:
- Quantum spin chains are fundamental models in condensed matter physics.
- Understanding transport properties, like spin current, is crucial for quantum systems.
- Zero-temperature studies reveal intrinsic quantum behaviors.
Purpose of the Study:
- To investigate the spin current variance in quantum spin chains at zero temperature.
- To derive an exact expression for the spin current variance in the XX model.
- To analyze the asymptotic behavior of the variance and its implications for related models.
Main Methods:
- Exact derivation of the spin current variance for the XX model.
- Analysis of the asymptotic behavior of the derived expression.
- Extrapolation of findings to the XXZ model in its critical region.
Main Results:
- An exact expression for the total spin current variance was derived for the XX model.
- The study revealed an anomalously slow logarithmic growth in the variance at asymptotic times.
- A subleading constant term in the variance was successfully extracted.
Conclusions:
- The logarithmic growth of spin current variance is a key characteristic of the XX model.
- This behavior is expected to persist in the XXZ model within its critical regime.
- The findings contribute to the understanding of quantum transport and critical phenomena in spin chains.
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