Pairing in fermionic systems: A quantum information perspective

Abstract

The notion of "paired" fermions is central to important condensed matter phenomena such as superconductivity and superfluidity. While the concept is widely used and its physical meaning is clear there exists no systematic and mathematical theory of pairing which would allow to unambiguously characterize and systematically detect paired states. We propose a definition of pairing and develop methods for its detection and quantification applicable to current experimental setups. Pairing is shown to be a quantum correlation different from entanglement, giving further understanding in the structure of highly correlated quantum systems. In addition, we will show the resource character of paired states for precision metrology, proving that the BCS states allow phase measurements at the Heisenberg limit.

23 pages, 4 figures

References in corpus (7)

• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Observation of Bose-Einstein Condensation of Molecules
• Entanglement entropy of fermions in any dimension and the Widom conjecture
• Molecular Probe of Pairing in the BEC-BCS Crossover
• Entanglement in fermionic systems
• Collective oscillations of a Fermi gas in the unitarity limit: Temperature effects and the role of pair correlations
• Structure of quantum correlations in momentum space and off diagonal long range order in eta pairing and BCS states