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Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Optical precursors with electromagnetically induced transparency in cold atoms
Dong Wei1, J F Chen, M M T Loy
1Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Physical Review Letters
|October 2, 2009
Summary
We observed optical precursors from laser pulses in atomic media. These precursors travel at light speed, showing unique behavior on rising and falling edges, especially in dense media.
Area of Science:
- Atomic physics
- Quantum optics
- Laser-matter interactions
Background:
- Electromagnetically induced transparency (EIT) enables control over light propagation in atomic media.
- Optical precursors are transient wave phenomena preceding a main pulse.
- Understanding light propagation in EIT media is crucial for quantum information and optical technologies.
Purpose of the Study:
- To investigate the generation and propagation of Sommerfeld-Brillouin optical precursors.
- To study the behavior of these precursors in a cold atomic ensemble with EIT.
- To analyze the influence of optical depth on precursor characteristics.
Main Methods:
- Generating optical precursors using a long square-modulated laser pulse.
- Propagating the pulse through a cold atomic ensemble exhibiting EIT.
- Varying the optical depth (alpha(0)L) of the atomic medium from 0 to 50.
Main Results:
- Observed optical precursors on both rising and falling edges of the laser pulse.
- Demonstrated that precursor edges propagate at the speed of light in vacuum, unaffected by slow light.
- Observed precursor separation from the main pulse at high optical depth and damped oscillations at the falling edge due to interference.
Conclusions:
- Sommerfeld-Brillouin precursors can propagate at the speed of light in EIT media.
- The optical depth significantly influences precursor behavior and its separation from the main pulse.
- Interference effects between precursors and the main pulse lead to observable phenomena at high optical depths.
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