Probing BCS pairing and quasiparticle formation in ultracold gases by Rydberg atom spectroscopy

Fuente: arXiv
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Main Authors: Rodríguez, Emilio Ramos, Gievers, Marcel, Schmidt, Richard
Format: Preprint
Published: 2025
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author Rodríguez, Emilio Ramos
Gievers, Marcel
Schmidt, Richard
author_facet Rodríguez, Emilio Ramos
Gievers, Marcel
Schmidt, Richard
contents Locally probing pairing in fermionic superfluids, ranging from micro- to macroscopic scales, has been a long-standing challenge. Here, we investigate a new approach that uses Rydberg impurities as a spectroscopic sensor of the surrounding strongly correlated state of ultracold paired fermions. The extended wavefunction of the Rydberg electron induces a finite-range potential that can bind atoms from the BCS medium, forming molecular states. As a consequence, the optical absorption spectrum of the impurity encodes key many-body properties. Using the functional determinant approach, we provide a direct measure of the superfluid gap through frequency shifts of dimer and trimer peaks. The spectra also reveal whether the Cooper pairs are broken or trapped intact. For static Rydberg atoms, we relate this signature of pairing to the suppression of the orthogonality catastrophe due to the superconducting gap resulting in the formation of well-defined polaron quasiparticles. Our work establishes Rydberg atom spectroscopy as a powerful local probe of strongly correlated matter.
format Preprint
id arxiv_https___arxiv_org_abs_2511_19191
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Probing BCS pairing and quasiparticle formation in ultracold gases by Rydberg atom spectroscopy
Rodríguez, Emilio Ramos
Gievers, Marcel
Schmidt, Richard
Quantum Gases
Locally probing pairing in fermionic superfluids, ranging from micro- to macroscopic scales, has been a long-standing challenge. Here, we investigate a new approach that uses Rydberg impurities as a spectroscopic sensor of the surrounding strongly correlated state of ultracold paired fermions. The extended wavefunction of the Rydberg electron induces a finite-range potential that can bind atoms from the BCS medium, forming molecular states. As a consequence, the optical absorption spectrum of the impurity encodes key many-body properties. Using the functional determinant approach, we provide a direct measure of the superfluid gap through frequency shifts of dimer and trimer peaks. The spectra also reveal whether the Cooper pairs are broken or trapped intact. For static Rydberg atoms, we relate this signature of pairing to the suppression of the orthogonality catastrophe due to the superconducting gap resulting in the formation of well-defined polaron quasiparticles. Our work establishes Rydberg atom spectroscopy as a powerful local probe of strongly correlated matter.
title Probing BCS pairing and quasiparticle formation in ultracold gases by Rydberg atom spectroscopy
topic Quantum Gases
url https://arxiv.org/abs/2511.19191