Cavity engineered phonon-mediated superconductivity in MgB$_2$ from first principles quantum electrodynamics

TL;DR

This paper theoretically demonstrates that vacuum electromagnetic fields in a cavity can significantly influence and potentially enhance the superconducting transition temperature of MgB$_2$ by modifying its phonon-mediated pairing mechanism, suggesting a new avenue for light-controlled superconductivity.

Contribution

It introduces a first-principles quantum electrodynamical density-functional theory approach to study cavity effects on superconductivity, revealing substantial potential for T$_{ m{c}}$ enhancement in MgB$_2$ under strong light-matter coupling.

Findings

Superconducting T$_{ m{c}}$ can be increased by up to 73% in ideal cavity conditions.

Realistic cavities may increase T$_{ m{c}}$ by at most 5 K due to photon vacuum fluctuations.

Strong light-matter coupling can non-perturbatively alter electronic and phononic properties of materials.

Abstract

Strong laser pulses can control superconductivity, inducing non-equilibrium transient pairing by leveraging strong-light matter interaction. Here we demonstrate theoretically that equilibrium ground-state phonon-mediated superconductive pairing can be affected through the vacuum fluctuating electromagnetic field in a cavity. Using the recently developed ab initio quantum electrodynamical density-functional theory approximation, we specifically investigate the phonon-mediated superconductive behavior of MgB$_2$ under different cavity setups and find that in the strong light-matter coupling regime its superconducting transition temperature can be, in principles, enhanced by $\approx 73\%$ ($\approx 40\%$) in an in-plane (out-of-plane) polarized cavity. However, in a realistic cavity, we expect the T$_{\rm{c}}$ of MgB$_2$ can increase, at most, by $5$ K via photon vacuum fluctuations. The results highlight that strong light-matter coupling in extended systems can profoundly alter material properties in a non-perturbative way by modifying their electronic structure and phononic dispersion at the same time. Our findings indicate a pathway to the experimental realization of light-controlled superconductivity in solid-state materials at equilibrium via cavity-material engineering.