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Enhanced decoherence in the vicinity of a phase transition
1Laboratoire de Physique Théorique de la Matière Condensée, UMR 7600, Université Pierre et Marie Curie, Jussieu, Paris-75005, France.
Physical Review Letters
|February 1, 2008
Summary
Quantum spin decoherence accelerates near critical environments. Approaching a phase transition, critical fluctuations in spin baths enhance central spin decoherence, peaking at zero temperature.
Area of Science:
- Quantum physics
- Condensed matter physics
Background:
- Decoherence is a key process in quantum systems, leading to loss of quantum properties.
- Phase transitions in magnetic systems, like the Heisenberg model, are crucial for understanding collective spin behavior.
Purpose of the Study:
- To investigate the decoherence of a spin-1/2 system coupled to an environment near a continuous phase transition.
- To analyze the impact of critical fluctuations on quantum decoherence rates.
Main Methods:
- Studying spin environments modeled by ferromagnetic and antiferromagnetic Heisenberg models on a square lattice.
- Analyzing the weak coupling regime between a central spin and the spin bath.
- Examining the behavior of decoherence rates as the system approaches the transition temperature and zero temperature.
Main Results:
- Critical fluctuations near the phase transition temperature enhance the decoherence rate of the central spin.
- Decoherence is found to be maximal at zero temperature.
- The Markovian decoherence rate diverges at zero temperature, indicating a significant increase in decoherence.
Conclusions:
- Environmental critical fluctuations play a significant role in accelerating quantum decoherence.
- The zero-temperature phase transition point represents a regime of maximal decoherence for the studied spin system.
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