Symmetry restoration and quantumness reestablishment
arXiv:1407.0646 · doi:10.1038/srep06377
Abstract
A realistic quantum many-body system, characterized by a generic microscopic Hamiltonian, is accessible only through approximation methods. The mean field theories, as the simplest practices of approximation methods, commonly serve as a powerful tool, but unfortunately often violate the symmetry of the Hamiltonian. The conventional BCS theory, as an excellent mean field approach, violates the particle number conservation and completely erases quantumness characterized by concurrence and quantum discord between different modes. We restore the symmetry by using the projected BCS theory and the exact numerical solution and find that the lost quantumness is synchronously reestablished. We show that while entanglement remains unchanged with the particle numbers, quantum discord behaves as an extensive quantity with respect to the system size. Surprisingly, discord is hardly dependent on the interaction strengths. The new feature of discord offers promising applications in modern quantum technologies.
arXiv comment17 pages and 3 figures
References in corpus (23)
- Entanglement of Formation of an Arbitrary State of Two Qubits
- Introducing Quantum Discord
- Classical, quantum and total correlations
- Quantum discord and the power of one qubit
- Quantum discord for two-qubit X-states
- On the quantum, classical and total amount of correlations in a quantum state
- Classical Correlation and Quantum Discord in Critical Systems
- Sudden transition between classical and quantum decoherence
- Classical and quantum correlations under decoherence
- Almost all quantum states have non-classical correlations
- Local versus non-local information in quantum information theory: formalism and phenomena
- Quantum discord of two-qubit X-states
- Classical Correlations and Entanglement in Quantum Measurements
- Quantum discord and geometry for a class of two-qubit states
- A small superconducting grain in the canonical ensemble
- Polynomial-Time Simulation of Pairing Models on a Quantum Computer
- Upper bound and shareability of quantum discord based on entropic uncertainty relations
- Long-range quantum discord in critical spin systems
- Dressed Qubits
- Finite-size scaling exponents and entanglement in the two-level BCS model
- SO(5) as a Critical Dynamical Symmetry in the SU(4) Model of High-Temperature Superconductivity
- The Dual Roles of Quantum Discord in a Non-demolition Probing Task
- Entanglement and Concurrence in the BCS State