Donelli, Beatrice (2024) Josephson currents in Superfluids and Supersolids. [Tesi di dottorato]
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| Tipologia del documento: | Tesi di dottorato |
|---|---|
| Lingua: | English |
| Titolo: | Josephson currents in Superfluids and Supersolids |
| Autori: | Autore Email Donelli, Beatrice beatrice.donelli@unina.it |
| Data: | 15 Gennaio 2024 |
| Numero di pagine: | 171 |
| Istituzione: | Università degli Studi di Napoli Federico II |
| Dipartimento: | Fisica |
| Dottorato: | Quantum Technologies (Tecnologie Quantistiche) |
| Ciclo di dottorato: | 36 |
| Coordinatore del Corso di dottorato: | nome email Tafuri, Francesco francesco.tafuri@unina.it |
| Tutor: | nome email Smerzi, Augusto [non definito] Pezzè, Luca [non definito] |
| Data: | 15 Gennaio 2024 |
| Numero di pagine: | 171 |
| Parole chiave: | quantum gases; ultracold atoms; josephson junction; superfluidity; supersolidity |
| Settori scientifico-disciplinari del MIUR: | Area 02 - Scienze fisiche > FIS/03 - Fisica della materia |
| Depositato il: | 17 Gen 2024 16:40 |
| Ultima modifica: | 16 Apr 2025 13:51 |
| URI: | http://www.fedoa.unina.it/id/eprint/15584 |
Abstract
This PhD thesis, structured into five chapters, delves into the theoretical exploration of Josephson currents in ultracold quantum gases, with a particular focus on superfluids and supersolids. The initial chapter introduces the foundational concepts of ultracold quantum gases, including superfluidity and the dipolar interaction, leading to the formation of dipolar supersolids. The second chapter provides a theoretical framework for Josephson junctions, keeping an eye on the bosonic case, setting the stage for the other chapters which describe the results of two main projects. The first project investigates self-induced Josephson junctions in a dipolar supersolid, employing a 3D numerical simulation based on the extended Gross-Pitaevskii equation (eGPE). This work predicts and observes Josephson oscillations and macroscopic quantum self-trapping (MQST) in the supersolid system. It also provides a theoretical 2M-mode model which generalizes the standard two-mode model for bosonic Josephson junctions whose results align well with numerical simulations. Collaboration with the experimental group in Pisa led by prof. Modugno validates the theory, revealing Josephson frequencies and superfluid fraction measurements. The findings, emphasizing a sub-unity superfluid fraction, offer insights into novel phenomena and potential applications of Josephson junctions. The second project, in collaboration with another experimental group in Florence led by prof. Roati, explores the stability of supercurrent states in a Lithium molecular Bose-Einstein condensate (BEC) within an atomtronic ring. Through analytical studies and 3D numerical simulations, this research demonstrates that the increase of the number of Josephson junctions enhances the stability of superfluid currents, opening avenues for precise control in atomtronic circuits.
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