Do you want to publish a course? Click here

Bosonic Condensation and Disorder-Induced Localization in a Flat Band

125   0   0.0 ( 0 )
 Added by Florent Baboux
 Publication date 2015
  fields Physics
and research's language is English




Ask ChatGPT about the research

We report on the engineering of a non-dispersive (flat) energy band in a geometrically frustrated lattice of micro-pillar optical cavities. By taking advantage of the non-hermitian nature of our system, we achieve bosonic condensation of exciton-polaritons into the flat band. Due to the infinite effective mass in such band, the condensate is highly sensitive to disorder and fragments into localized modes reflecting the elementary eigenstates produced by geometric frustration. This realization offers a novel approach to studying coherent phases of light and matter under the controlled interplay of frustration, interactions and dissipation.



rate research

Read More

One of the recently established paradigms in the study of condensed matter physics is examining a systems behaviour in artificially constructed potentials. This allows one to obtain insight on a range of physical phenomena which may require non-feasible or hardly achievable experimental conditions. Here, we devise and implement an all-optical approach to a system of exciton-polaritons in semiconductor microcavities to load the particles into desired periodic potentials. We demonstrate a two-dimensional system of polariton condensates in two regimes - lattices of point scatterers, and confined states through non-resonant pumping with Gaussian beams arranged in a conventional, and an inverse Lieb configuration. We utilize energy tomography on the coherent polariton emission to reveal the intricate band structure of polaritonic Lieb lattices, and report on fully optically generated polariton condensation in S-, and dispersionless P-band states.
Modulational instabilities play a key role in a wide range of nonlinear optical phenomena, leading e.g. to the formation of spatial and temporal solitons, rogue waves and chaotic dynamics. Here we experimentally demonstrate the existence of a modulational instability in condensates of cavity polaritons, arising from the strong coupling of cavity photons with quantum well excitons. For this purpose we investigate the spatiotemporal coherence properties of polariton condensates in GaAs-based microcavities under continuous-wave pumping. The chaotic behavior of the instability results in a strongly reduced spatial and temporal coherence and a significantly inhomogeneous density. Additionally we show how the instability can be tamed by introducing a periodic potential so that condensation occurs into negative mass states, leading to largely improved coherence and homogeneity. These results pave the way to the exploration of long-range order in dissipative quantum fluids of light within a controlled platform.
195 - Yanyan He , Ruosong Mao , Han Cai 2020
Flat bands play an important role in diffraction-free photonics and attract fundamental interest in many-body physics. Here we report the engineering of flat-band localization of collective excited states of atoms in Creutz superradiance lattices with tunable synthetic gauge fields. Magnitudes and phases of the lattice hopping coefficients can be independently tuned to control the state components of the flat band and the Aharonov-Bohm phases. We can selectively excite the flat band and control the flat-band localization with the synthetic gauge field. Our study provides a room-temperature platform for flat bands of atoms and holds promising applications in exploring correlated topological materials.
Quantum walks are processes that model dynamics in coherent systems. Their experimental implementations proved key to unveil novel phenomena in Floquet topological insulators. Here we realize a photonic quantum walk in the presence of a synthetic gauge field, which mimics the action of an electric field on a charged particle. By tuning the energy gaps between the two quasi-energy bands, we investigate intriguing system dynamics characterized by the interplay between Bloch oscillations and Landau-Zener transitions. When both gaps at quasi-energy values 0 and $pi$ are vanishingly small, the Floquet dynamics follows a ballistic spreading.
Non-Hermitian systems can host topological states with novel topological invariants and bulk-edge correspondences that are distinct from conventional Hermitian systems. Here we show that two unique classes of non-Hermitian 2D topological phases, a 2$mathbb{Z}$ non-Hermitian Chern insulator and a $mathbb{Z}_{2}$ topological semimetal, can be realized by tuning staggered asymmetric hopping strengths in a 1D superlattice. These non-Hermitian topological phases support real edge modes due to robust $mathcal{PT}$-symmetric-like spectra and can coexist in certain parameter regime. The proposed phases can be experimentally realized in photonic or atomic systems and may open an avenue for exploring novel classes of non-Hermitian topological phases with 1D superlattices.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا