2020 Fiscal Year Research-status Report
Quantum vortex dynamics in exotic superfluid systems
| Project/Area Number |
20K14376
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| Research Institution | Keio University |
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Principal Investigator |
エドモンズ マシュー 慶應義塾大学, 自然科学研究教育センター(日吉), 訪問研究員 (00865230)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | ultracold atoms / BEC / vortices / gauge fields |
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| Outline of Annual Research Achievements |
We have theoretically examined the vortex states of a gas of trapped quasi-two-dimensional ultracold bosons subject to a density-dependent gauge potential, realizing an effective nonlinear rotation of the atomic condensate, which we also have shown is within the reach of current experimental techniques with ultracold atom experiments. The nonlinear rotation has a twofold effect; as well as distorting the shape of the condensate it also leads to an inhomogeneous vorticity resulting in unique morphological and topological states, including ring vortex arrangements that do not follow the standard Abrikosov result. The dynamics of trapped vortices are also explored.
We have explored the effect of using two-dimensional matter-wave vortices to confine an ensemble of bosonic quantum impurities. This is modelled theoretically using a mass-imbalanced homogeneous two component Gross-Pitaevskii equation where each component has independent atom numbers and equal atomic masses. By changing the mass imbalance of our system we have found the shape of the vortices are deformed even at modest imbalances, leading to barrel shaped vortices; which we have quantified using a multi-component variational approach. The energy of impurity carrying vortex pairs have been computed, revealing a mass-dependent energy splitting. We then have computed the excited states of the impurity, which we in turn have used to construct `covalent bonds' for vortex pairs. Our work opens a new route to simulating synthetic chemical reactions with superfluid systems.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Progress so far has been smooth, since two publications have been written.
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| Strategy for Future Research Activity |
I will study vortices of the second component inside a large vortex of the first component in two-component Bose-Einstein condensates.
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| Causes of Carryover |
Because of the COVID-19 pandemic, I could not use the grant for traveling of myself, and honorarium and travel cost for invited speakers, both of which were supposed to be the main use of the grant.
In this academic year, I plan to use it for article costs, publication fee, honorarium for speakers of online seminars, and so on.
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