Superconductivity, Superfluidity and Holography

TL;DR

This review explores holographic models of superconductors and superfluids, emphasizing physical insights, predictions, and the effects of extra dimensions or dilatonic fields on phenomena like the Little-Parks effect and phase transitions.

Contribution

It provides a comprehensive overview of holographic superconductor and superfluid models, including novel insights into gapped systems and the role of extra dimensions in physical phenomena.

Findings

Holographic models predict universal properties like Little-Parks periodicity.

Large R suppresses non-local operators, revealing local behavior.

Phase transitions correspond to Hawking-Page transitions in gravity.

Abstract

This is a concise review of holographic superconductors and superfluids. We highlight some predictions of the holographic models and the emphasis is given to physical aspects rather than to the technical details, although some references to understand the latter are systematically provided. We include gapped systems in the discussion, motivated by the physics of high-temperature superconductivity. In order to do so we consider a compactified extra dimension (with radius R), or, alternatively, a dilatonic field. The first setup can also be used to model cylindrical superconductors; when these are probed by an axial magnetic field a universal property of holography emerges: while for large R (compared to the other scales in the problem) non-local operators are suppressed, leading to the so called Little-Parks periodicity, the opposite limit shows non-local effects, e.g. the uplifting of the Little-Parks periodicity. This difference corresponds in the gravity side to a Hawking-Page phase transition.