Communal pairing in Fermi gases with attractive interactions

Weak attractive interactions in a spin-balanced fermion gas are known to induce a Cooper pairing instability where the fermion pairs have zero net momentum, leading to BCS superconductivity. Extensions for spin-imbalanced systems include breached superfluids, Fulde–Ferrell–Larkin–Ovchinnikov theory, and pair density wave theory. We propose a further extension of a superconducting state, dubbed a communal pairing state, whose underlying components are superpositions of Cooper pairs that share minority-spin fermions. This state includes correlations between all available fermions on both Fermi surfaces and is shown to be energetically favourable to the Fulde-Ferrell-Larkin-Ovchinnikov state. Our numerical quantum Monte Carlo study of finite spin-imbalanced systems provides clear evidence of the existence of such exotic pairing states. In spin-balanced systems, temporal fluctuations of the order parameter promote communal pairing, leading to a widening in momentum space of the superconducting gap and a decrease of the chemical potential.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2020

Author dc:creator

• Foo, Darryl

Advisor dc:contributor.advisor

• Conduit, Gareth

• Superconductors
• Fermi gases
• Computational physics

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/35a6a96e-4563-41cb-b1db-267c3c851657/download
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

eng

Author Identifier

0000-0001-7565-1383
0000-0003-3807-6361

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/319139