Finite-temperature spectrum at the symmetry-breaking linear to zigzag transition

verfasst von
Jan Kiethe, Lars Timm, Haggai Landa, Dimitri Kalincev, Giovanna Morigi, Tanja E. Mehlstäubler
Abstract

We investigate the normal-mode spectrum of a trapped ion chain at the symmetry-breaking linear to zigzag transition and at finite temperatures. For this purpose, we modulate the amplitude of the Doppler cooling laser to excite and measure mode oscillations. The expected mode softening at the critical point, a signature of the second-order transition, is not observed. Numerical simulations show that this is mainly due to the finite temperature of the chain. Inspection of the trajectories suggest that the thermal shifts of the normal-mode spectrum can be understood by the ions collectively jumping between the two ground-state configurations of the symmetry-broken phase. We develop an effective analytical model, which allows us to reproduce the low-frequency spectrum as a function of the temperature and close to the transition point. In this model, the frequency shift of the soft mode is due to the anharmonic coupling with the high-frequency modes of the spectrum, acting as an averaged effective thermal environment. Our study could prove important for implementing ground-state laser cooling close to the critical point.

Organisationseinheit(en)
Institut für Theoretische Physik
Institut für Quantenoptik
QuantumFrontiers
SFB 1227: Designte Quantenzustände der Materie (DQ-mat)
Externe Organisation(en)
Physikalisch-Technische Bundesanstalt (PTB)
Universität Paris-Saclay
University of Haifa
Universität des Saarlandes
Typ
Artikel
Journal
Physical Review B
Band
103
ISSN
2469-9950
Publikationsdatum
19.03.2021
Publikationsstatus
Veröffentlicht
Peer-reviewed
Ja
ASJC Scopus Sachgebiete
Elektronische, optische und magnetische Materialien, Physik der kondensierten Materie
Elektronische Version(en)
https://doi.org/10.1103/PhysRevB.103.104106 (Zugang: Offen)