We demonstrate an intricate combination of strong and weak interactions of a broadband half-cycle pulse with Rydberg atoms. A transition, which is resonant with a frequency that was taken out of the frequency spectrum, can be enhanced. In the experiment, the broadband ultrashort terahertz half-cycle pulse propagates through water vapor, which absorbs on discrete lines in the spectrum, thus removing frequencies from the spectrum. The resulting pulse interacts with a rubidium Rydberg atom, which has a resonant transition with one of the missing frequencies. Under certain conditions, the transition probability is enhanced although the associated frequency was missing in the spectrum.
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http://dx.doi.org/10.1103/PhysRevLett.93.153002 | DOI Listing |
Sci Rep
November 2024
Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA.
A laser pulse composed of a fundamental and an appropriately phased second harmonic can drive a time-dependent current of photoionized electrons that generates broadband THz radiation. Over the propagation distances relevant to many experiments, dispersion causes the relative phase between the harmonics to evolve. This "dephasing" slows the accumulation of THz energy and results in a multi-cycle THz pulse with significant angular dispersion.
View Article and Find Full Text PDFNano Lett
September 2024
Institut für Physik and Center for Nanoscale Dynamics (CeNaD), Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky Str. 9-11, 26129 Oldenburg, Germany.
Sci Rep
August 2024
Mechanical Engineering Department, Arak University of Technology, Arak, Iran.
Controlling wind flow on vertical axis wind turbine blades is an effective technique for enhancing their performance. Modern equipment such as plasma actuators have gained significant attention for their ability to control, and improve the flow behavior in wind turbines. Previous studies have primarily focused on investigating plasma actuators with constant force.
View Article and Find Full Text PDFWe theoretically demonstrate the possibility to tune the temporal waveform of unipolar pulses of femtosecond duration emitted from a multilevel resonant medium. This is achieved through the control of the medium response by a properly adjusted sequence of half-cycle unipolar or quasi-unipolar driving pulses and the spatial density profile of resonant centers along the medium layer. We show the production of unipolar optical pulses of varying profiles, like rectangular or triangular ones, from an extended layer of a multilevel medium.
View Article and Find Full Text PDFNat Commun
October 2023
Szentágothai Research Centre, University of Pécs, 7624, Pécs, Hungary.
The advent of intense terahertz (THz) sources opened a new era when the demonstration of the acceleration and manipulation of free electrons by THz pulses became within reach. THz-field-driven electron emission was predicted to be confined to a single burst due to the single-cycle waveform. Here we demonstrate the confinement of single-cycle THz-waveform-driven electron emission to one of the two half cycles from a solid surface emitter.
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