Orientational Melting in a Mesoscopic System of Charged Particles

Year: 2023

Authors: Duca L., Mizukami N., Perego E., Inguscio M., Sias C.

Autors Affiliation: Ist Nazl Ric Metrol INRiM, I-10135 Turin, Italy; European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; Politecn Torino, I-10129 Turin, Italy; Ist Nazl Ott Consiglio Nazl Ric CNR INO, I-50019 Sesto Fiorentino, Italy; Univ Rome, Dept Engn, Campus Biomedico, I-00128 Rome, Italy; Univ Calif Berkeley, Dept Phys, Berkeley, CA USA.

Abstract: A mesoscopic system of a few particles can undergo changes of configuration that resemble phase transitions but with a nonuniversal behavior. A notable example is orientational melting, in which localized particles with long-range repulsive interactions forming a two-dimensional crystal become delocalized in common closed trajectories. Here we report the observation of orientational melting occurring in a two-dimensional crystal of up to 15 ions. We measure density-density correlations to quantitatively characterize the occurrence of melting, and use a Monte Carlo simulation to extract the angular kinetic energy of the ions. By adding a pinning impurity, we demonstrate the nonuniversality of orientational melting and create novel configurations in which localized and delocalized particles coexist. Our system realizes an experimental testbed for studying changes of configurations in two-dimensional mesoscopic systems, and our results pave the way for the study of quantum phenomena in ensembles of delocalized ions.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 131 (8)      Pages from: 83602-1  to: 83602-7

More Information: We gratefully thank Federico Berto, Roberto Concas, and Amelia Detti for their support in the realization of the experimental apparatus. We thank Guido Pupillo, Michael Drewsen, Chiara Menotti, Giovanna Morigi, and the Quantum Gases group at LENS for fruitful discussions. Moreover, we are grateful to Martina Knoop, Boris Blinov, and Guenter Werth for helpful discussions during the assembly of the experimental setup. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No. 639242). This work was financially supported by the FARE-MIUR grant UltraCrystals (Grant No. R165JHRWR3).
KeyWords: Phase-transitions; Coulomb Clusters; 2-ion Crystals; Crystallization; Prediction
DOI: 10.1103/PhysRevLett.131.083602

Citations: 3
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