Mesoscopic pairing without superconductivity

Abstract

We discuss pairing signatures in mesoscopic nanowires with variable attractive pairing interaction. Depending on wire length, density, and interaction strength, these systems realize a simultaneous bulk-to-mesoscopic and BCS-BEC crossover, which we describe in terms of the parity parameter that quantifies the odd-even energy difference and generalizes the bulk Cooper pair binding energy to mesoscopic systems. We show that the parity parameter can be extracted from recent measurements of conductance oscillations in SrTiO${}_3$ nanowires by G. Cheng et al. [Nature 521, 196 (2015)], where it marks the critical magnetic field that separates pair and single-particle currents. Our results place the experiment in the fluctuation-dominated mesoscopic regime on the BCS side of the crossover.

6 pages, 4 figures

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• Theory of ultracold Fermi gases
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• The Crossover from the Bulk to the Few-Electron limit in Ultrasmall Metallic Grains
• Tunable electron-electron interactions in LaAlO3/SrTiO3 nanostructures
• Finite Size Corrections for the Pairing Hamiltonian
• Spectral convexity for attractive SU(2N) fermions
• Strongly Interacting Fermi Gases
• Evidence for Superconducting Phase Coherence in the Metallic/Insulating Regime of the LaAlO3-SrTiO3 Interface Electron System
• Parity effect in a mesoscopic Fermi gas

Cited by in corpus (6)

• Superconductivity in dilute SrTiO${}_3$: a review
• Analytic approach to transport in superconducting junctions with arbitrary carrier density
• Nonrelativistic Conformal Invariance in Mesoscopic Two-Dimensional Fermi Gases
• Few-body perspective on fermionic pairing in one spatial dimension
• Few-to-many-particle crossover of pair excitations in a superfluid
• Stability conditions for a large anharmonic bipolaron