Abstract
The possible phases and the nanoscale particle correlations of two-dimensional interacting dipolar particles is a long-sought problem in many-body physics. Here we observe a spontaneous condensation of trapped two-dimensional dipolar excitons with internal spin degrees of freedom from an interacting gas into a high density, closely packed liquid state made mostly of dark dipoles. Another phase transition, into a bright, highly repulsive plasma, is observed at even higher excitation powers. The dark liquid state is formed below a critical temperature Tc ≈ 4.8 K, and it is manifested by a clear spontaneous spatial condensation to a smaller and denser cloud, suggesting an attractive part to the interaction which goes beyond the purely repulsive dipole-dipole forces. Contributions from quantum mechanical fluctuations are expected to be significant in this strongly correlated, long living dark liquid. This is a new example of a two-dimensional atomic-like interacting dipolar liquid, but where the coupling of light to its internal spin degrees of freedom plays a crucial role in the dynamical formation and the nature of resulting condensed dark ground state.
Original language | English (US) |
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Pages (from-to) | 3726-3731 |
Number of pages | 6 |
Journal | Nano Letters |
Volume | 16 |
Issue number | 6 |
DOIs | |
State | Published - Jun 8 2016 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Bioengineering
- General Chemistry
- General Materials Science
- Condensed Matter Physics
- Mechanical Engineering
Keywords
- cold dipolar gas
- dark excitons
- dipolar excitons
- exciton condensation
- Indirect excitons
- quantum fluids