What is it about?
Quantum vortices are typical structure of superfluids, Bose Einstein condensates or optical beams. In them the field is rotating around the centre at the typical frequency of the wavefunction. We have put the centre to one of these vortices into an ultrafast rotation itself inside a microcavity device. It is resembling an ultrafast and tiny swirling tornado made of polaritons, the mixed waves of photons and electronic excitons.
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Why is it important?
The vortex motion is due to an interplay of the spatially varying phase and the Rabi frequency. The Rabi oscillations are typical in strongly coupled multicomponent condensates. In optical terms, it is equivalent to an effect of interference between the normal modes of the structure. The double spiraling motion of the vortex centre can achieve diverging velocities when far from the initial centre. The associated linear and angular momentum of the emitted light is oscillating too. The dynamics can be described in terms of a fundamental homeomorphism (bijection), the stereographic mapping between the Bloch sphere of the polariton state and the real space where the observation is made. These effects can shed light also to hidden levels of topology.
Perspectives
The investigation of such vector texture in 2D and 3D spaces allow to identify beautiful underlying links with topological concepts, such as the Berry curvature, and have new intuitions on already known structures and forces, or even to think about new interpretations.
Dr Lorenzo Dominici
CNR NANOTEC, Institute of Nanotechnology
Read the Original
This page is a summary of: Full-Bloch beams and ultrafast Rabi-rotating vortices, Physical Review Research, January 2021, American Physical Society (APS),
DOI: 10.1103/physrevresearch.3.013007.
You can read the full text:
Resources
Experimental Rabi vortex dynamics.
Photonic amplitude and phase in a 100×100μm area, with 20 fs time step. The Gaussian beam is arriving at around t= 1.6 ps. The vortex core position is marked with a yellow dot in the amplitude map.
Model Rabi vortex dynamics.
Maps and dynamics of four relevant quantities, namely the local imbalance s(r,t) and the relative phase φLU(r,t) on the top row (blue-green map and black and white map), and the photon and exciton densities|ψC,X(r,t)| (blue, red) in the second row. The fixed blue andg reen dots mark the fixed in space UP and LP cores, respectively. The drifting white and black circles overlapped tothe photon and exciton densities represent the s= 0 isocontent line and the φLU= 0 ∪ φLU=π isophase lines,respectively. Their crossing points mark the moving photon and exciton cores (dark spots in the respective fields).
Standard rartex 3D video
Video highlights the density field of the spiraling Rabi vortex in a time span of some picosecond. The density hole depicts the core to the vortex which is looping itself. Also at https://polaritonics.nanotec.cnr.it/videos/video_rartex_3d_new_cut.mp4
The rartex, or Rabi vortex. A quantum vortex where the core is spiraling itself.
Standard Rabi vortex, 3D video. Video highlights the density field of the spiraling Rabi vortex in a time span of some picoseconds. The density hole depicts the core to the vortex which is looping itself. From the model used in Full-Bloch beams and ultrafast Rabi-rotating vortices, Phys. Rev. Research 3, 013007 (2021)
Contributors
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