2013 Fiscal Year Final Research Report
Cooper pair liquid phase and pseudogap effect of attractive fermions in a honeycomb optical lattice
| Project/Area Number |
24740276
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Atomic/Molecular/Quantum electronics
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | 蜂の巣光格子 / 冷却フェルミ気体 / クーパー対液体 / 擬ギャップ / ヒッグスモード / ディラックフェルミオン / クーペロン |
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| Research Abstract |
We propose the emergence of the novel quantum phase so called "Cooper pair liquid" and investigate the possibility of pseudogap effect in the vicinity of the quantum critical point between the semimetal and superfluid phases of attractive fermions in optical lattices with the honeycomb geometry. For this purpose, we study elementary excitation in the vicinity of the quantum critical point applying the generalized random phase approximation to the attractive Hubbard model. We find sharp collective mode excitations that are stable against decay into quasiparticle pairs. In the semimetal phase, the collective modes have "Cooperon" and exciton character. These modes smoothly evolve across the quantum phase transition, and become Anderson mode and the Higgs mode that are associated with phase and amplitude fluctuation of the superfluid order parameter. The existence of these stable collective modes strongly implies the emergence of the Cooper pair liquid phase and the pseudogap effect.
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