Combined effect of thermal and quantum fluctuations in superconducting nanostructures: a path integral approach

Abstract

We study the combined effect of thermal and quantum fluctuations in a zero dimensional superconductor. By using path integral techniques, we obtain novel expressions for the partition function and the superconducting order parameter which include both types of fluctuations. Our results are valid for any temperature and to leading order in δ/Δ_{0} where δis the mean level spacing and Δ_{0} is the bulk energy gap. We avoid divergences at low temperatures, previously reported in the literature, by identifying and treating non-perturbatively a low-energy collective mode. In the low and high temperature limit our results agrees with those from the random phase (RPA) and the static path approximation (SPA) respectively.

4 pages, 2 figures

References in corpus (8)

• Pairing in nuclear systems: from neutron stars to finite nuclei
• Spectroscopy of discrete energy levels in ultrasmall metallic grains
• Quantum Tunneling of the Order Parameter in Superconducting Nanowires
• Observation of shell effects in superconducting nanoparticles of Sn
• Finite Size Corrections for the Pairing Hamiltonian
• Pairing of fermions in atomic traps and nuclei
• Shell structure and pairing for interacting fermions in a trap
• Description of thermal entanglement with the static path plus random-phase approximation

Cited by in corpus (4)

• Pairing of few Fermi atoms in one dimension
• Thermodynamics of ultrasmall metallic grains in the presence of pairing and exchange correlations: Mesoscopic fluctuations
• The coexistence of superconductivity and ferromagnetism in nano-scale metallic grains
• Interplay of classical and "quantum" capacitance in a one dimensional array of Josephson junctions