Decay of Persistent Currents in Annular Atomic Superfluids
We investigate the role of vortices in the decay of persistent current states of annular atomic superfluids by solving numerically the Gross–Pitaevskii equation, and we directly compare our results with the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display=&...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-07-01
|
| Series: | Atoms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-2004/11/8/109 |
| _version_ | 1797585514456416256 |
|---|---|
| author | Klejdja Xhani Giulia Del Pace Francesco Scazza Giacomo Roati |
| author_facet | Klejdja Xhani Giulia Del Pace Francesco Scazza Giacomo Roati |
| author_sort | Klejdja Xhani |
| collection | DOAJ |
| description | We investigate the role of vortices in the decay of persistent current states of annular atomic superfluids by solving numerically the Gross–Pitaevskii equation, and we directly compare our results with the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>6</mn></msup></semantics></math></inline-formula>Li experiment at LENS data. We theoretically model the optical phase-imprinting technique employed to experimentally excite finite-circulation states in the Bose–Einstein condensation regime, accounting for imperfections of the optical gradient imprinting profile. By comparing simulations of this realistic protocol to an ideal imprinting, we show that the introduced density excitations arising from imperfect imprinting are mainly responsible for limiting the maximum reachable winding number <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>max</mi></msub></semantics></math></inline-formula> in the superfluid ring. We also investigate the effect of a point-like obstacle with variable potential height <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> on the decay of circulating supercurrents. For a given obstacle height, a critical circulation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula> exists, such that for an initial circulation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mn>0</mn></msub></semantics></math></inline-formula> larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula> the supercurrent decays through the emission of vortices, which cross the superflow and thus induce phase slippage. Higher values of the obstacle height <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> further favor the entrance of vortices, thus leading to lower values of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula>. Furthermore, the stronger vortex-defect interaction at higher <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> leads to vortices that propagate closer to the center of the ring condensate. The combination of both these effects leads to an increase in the supercurrent decay rate for increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mn>0</mn></msub></semantics></math></inline-formula>, in agreement with experimental observations. |
| first_indexed | 2024-03-11T00:07:10Z |
| format | Article |
| id | doaj.art-1e89867b690d422bbb1cc6e208cf66da |
| institution | Directory Open Access Journal |
| issn | 2218-2004 |
| language | English |
| last_indexed | 2024-03-11T00:07:10Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atoms |
| spelling | doaj.art-1e89867b690d422bbb1cc6e208cf66da2023-11-19T00:13:50ZengMDPI AGAtoms2218-20042023-07-0111810910.3390/atoms11080109Decay of Persistent Currents in Annular Atomic SuperfluidsKlejdja Xhani0Giulia Del Pace1Francesco Scazza2Giacomo Roati3Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO) c/o LENS, 50019 Sesto Fiorentino, ItalyDepartment of Physics, University of Florence, 50019 Sesto Fiorentino, ItalyIstituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO) c/o LENS, 50019 Sesto Fiorentino, ItalyIstituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO) c/o LENS, 50019 Sesto Fiorentino, ItalyWe investigate the role of vortices in the decay of persistent current states of annular atomic superfluids by solving numerically the Gross–Pitaevskii equation, and we directly compare our results with the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>6</mn></msup></semantics></math></inline-formula>Li experiment at LENS data. We theoretically model the optical phase-imprinting technique employed to experimentally excite finite-circulation states in the Bose–Einstein condensation regime, accounting for imperfections of the optical gradient imprinting profile. By comparing simulations of this realistic protocol to an ideal imprinting, we show that the introduced density excitations arising from imperfect imprinting are mainly responsible for limiting the maximum reachable winding number <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>max</mi></msub></semantics></math></inline-formula> in the superfluid ring. We also investigate the effect of a point-like obstacle with variable potential height <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> on the decay of circulating supercurrents. For a given obstacle height, a critical circulation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula> exists, such that for an initial circulation <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mn>0</mn></msub></semantics></math></inline-formula> larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula> the supercurrent decays through the emission of vortices, which cross the superflow and thus induce phase slippage. Higher values of the obstacle height <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> further favor the entrance of vortices, thus leading to lower values of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mi>c</mi></msub></semantics></math></inline-formula>. Furthermore, the stronger vortex-defect interaction at higher <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>V</mi><mn>0</mn></msub></semantics></math></inline-formula> leads to vortices that propagate closer to the center of the ring condensate. The combination of both these effects leads to an increase in the supercurrent decay rate for increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>w</mi><mn>0</mn></msub></semantics></math></inline-formula>, in agreement with experimental observations.https://www.mdpi.com/2218-2004/11/8/109Bose–Einstein condensatespersistent currentssuperfluidsvorticesphase-slippagesolitons |
| spellingShingle | Klejdja Xhani Giulia Del Pace Francesco Scazza Giacomo Roati Decay of Persistent Currents in Annular Atomic Superfluids Atoms Bose–Einstein condensates persistent currents superfluids vortices phase-slippage solitons |
| title | Decay of Persistent Currents in Annular Atomic Superfluids |
| title_full | Decay of Persistent Currents in Annular Atomic Superfluids |
| title_fullStr | Decay of Persistent Currents in Annular Atomic Superfluids |
| title_full_unstemmed | Decay of Persistent Currents in Annular Atomic Superfluids |
| title_short | Decay of Persistent Currents in Annular Atomic Superfluids |
| title_sort | decay of persistent currents in annular atomic superfluids |
| topic | Bose–Einstein condensates persistent currents superfluids vortices phase-slippage solitons |
| url | https://www.mdpi.com/2218-2004/11/8/109 |
| work_keys_str_mv | AT klejdjaxhani decayofpersistentcurrentsinannularatomicsuperfluids AT giuliadelpace decayofpersistentcurrentsinannularatomicsuperfluids AT francescoscazza decayofpersistentcurrentsinannularatomicsuperfluids AT giacomoroati decayofpersistentcurrentsinannularatomicsuperfluids |