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Symmetry restoration and quantumness reestablishment
Guo-Mo Zeng1, Lian-Ao Wu2, Hai-Jun Xing1
1College of Physics, Jilin University, Changchun 130012, China.
Scientific Reports
|September 19, 2014
Summary
Projected BCS theory restores particle number conservation and quantumness in many-body systems. Quantum discord, a key quantum feature, is reestablished and shows unique system-size scaling, offering new quantum technology applications.
Area of Science:
- Quantum many-body physics
- Quantum information theory
- Condensed matter theory
Background:
- Realistic quantum systems require approximation methods like mean-field theories.
- Conventional methods, such as BCS theory, often violate system symmetries and erase quantum information.
- Particle number non-conservation and loss of quantum correlations are significant limitations.
Purpose of the Study:
- To restore broken symmetries in mean-field approaches for quantum many-body systems.
- To reestablish lost quantum correlations, specifically quantum discord and entanglement.
- To investigate the behavior of quantum discord with system size and interaction strength.
Main Methods:
- Utilizing projected BCS theory to enforce particle number conservation.
- Employing exact numerical solutions for validation.
- Analyzing quantum correlations, including concurrence and quantum discord.
Main Results:
- Symmetry restoration in projected BCS theory reestablishes lost quantumness.
- Entanglement is invariant to particle number changes.
- Quantum discord exhibits extensive scaling with system size and minimal dependence on interaction strength.
Conclusions:
- Projected BCS theory successfully restores symmetry and quantum information in many-body systems.
- Quantum discord's unique properties present opportunities for quantum technologies.
- The findings highlight the importance of symmetry in preserving quantum correlations.
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