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A novel approach to implement and control electron injection into the accelerating phase of a laser wakefield accelerator (LWFA) is presented. It utilizes a wire, which is introduced into the flow of a supersonic gas jet creating shock…

We report on time-resolved mid-infrared-pump terahertz-transmission-probe studies of the topological-insulator materials $(Bi_{1-x}Sb_{x})_{2}Te_{3}$, in which by varying x charge carriers are chemically tuned to be of n-type or p-type.…

We study the entanglement between the internal electronic and the external vibrational degrees of freedom of a trapped atom which is driven by two lasers into electromagnetically-induced transparency. It is shown that basic features of the…

Quantum Physics · Physics 2011-01-31 Maryam Roghani , Hanspeter Helm , Heinz-Peter Breuer

The transition energy must be crossed in the CERN PS to accelerate proton and ion beams to flat-top energy. A phase jump of the accelerating RF voltage with respect to the phase of the bunches by about 180 degrees minus twice the…

Accelerator Physics · Physics 2019-10-16 Heiko Damerau

Surface acceleration of fast electrons in intense laser-plasma interaction is improved by using sub-wavelength grating targets. The fast electron beam emitted along the target surface was enhanced by more than three times relative to that…

We consider self-pulsing in lasers with a gain section and an absorber section via a mechanism known as Q-switching, as described mathematically by the Yamada ordinary differential equation model for the gain, the absorber and the laser…

Dynamical Systems · Mathematics 2020-12-30 Robert Otupiri , Bernd Krauskopf , Neil G. R. Broderick

Energy-transfer efficiency is an important quantity in plasma-wakefield acceleration, especially for applications that demand high average power. Conventionally, the efficiency is measured using an electron spectrometer; an invasive method…

Spatial distributions of electrons ionized and scattered from ultra-low pressure gases are proposed and experimentally demonstrated as a method to directly measure the intensity of an ultra-high intensity laser pulse. Analytic models…

Despite exhibiting novel radiation features, the operation of the proposed quantum free-electron laser would have the drawback that the number of emitted photons is limited by one per electron, significantly reducing the output power of…

Quantum Physics · Physics 2023-03-29 Peter Kling , Enno Giese

Dielectric laser acceleration (DLA) achieves remarkable gradients from the optical near fields of a grating structure. Tilting the dielectric grating with respect to the electron beam leads to deflection forces and the DLA structure can be…

Accelerator Physics · Physics 2022-09-21 Steffen A. Schmid , Uwe Niedermayer

Distribution of the entangled state of trapped atomic ions to long distance using quantum repeater protocol is considered. Indeed, the long distance is divided into short parts, and then using entanglement generation and entanglement…

Quantum Physics · Physics 2021-06-04 M Ghasemi , M K Tavassoly

We consider the phase stability of a local oscillator (or laser) locked to a cavity QED system comprised of atoms with an ultra-narrow optical transition. The atoms are cooled to millikelvin temperatures and then released into the optical…

Quantum Physics · Physics 2015-06-30 D. A. Tieri , J. Cooper , Bjarke T. R. Christensen , J. W. Thomsen , M. J. Holland

The ultrafast dynamic evolution of an atomic system under medium-strength laser fields is studied by performing transient absorption measurement. An analytical model developed from perturbation theory with a modified transition dipole…

Atomic Physics · Physics 2019-05-22 Zhenhao Wang , Yu He , Quanjun Wang , Jingjie Ding , Shaohua Sun , Zuoye Liu , Bitao Hu

We demonstrate the ability to excite atoms at well-defined, programmable locations in a magneto-optical trap, either to the continuum (ionisation), or to a Rydberg state. To this end, excitation laser light is shaped into arbitrary…

Both theoretical and numerical analyses are conducted to investigate terahertz (THz) radiation emission from free-electron lasers. The angular and spectral characteristics of radiation are analytically evaluated leveraging Linenard Wiechert…

Accelerator Physics · Physics 2026-04-28 A. A. Molavi Choobini , S. S. Ghaffari-Oskooei , F. Farahi , F. M. Aghamir

We present measurements of slice energy spread growth due to quantum fluctuations of the undulator radiation at the European X-Ray Free-Electron Laser. The method uses a recently installed diagnostic wakefield structure, which enables…

Accelerator Physics · Physics 2022-08-16 Sergey Tomin , Evgeny Schneidmiller , Winfried Decking

Terawatt x-ray free-electron lasers (XFELs) require high current densities with strong transverse focusing. The implications on harmonic generation are discussed using the MINERVA simulation code which self-consistently includes harmonic…

Accelerator Physics · Physics 2024-01-19 Henry P. Freund , Patrick G. O'Shea

Plasma-based accelerators are a promising approach for reducing the size and cost of future particle accelerators, making them a viable technology for constructing and upgrading X-ray free-electron lasers (FELs). Adding an energy booster…

Accelerator Physics · Physics 2024-07-23 Sarah Schroeder , Jens Osterhoff , Stephan Wesch , Carl Schroeder

We report the first experimental observation of carrier-envelope phase-driven energy bunching in laser wakefield acceleration. Using a few-cycle (~9 fs), multi-terawatt laser pulse and ionization injection in a helium-nitrogen gas mixture,…

Two beam broadening methods for active electronically scanned array (AESA) antennas with uniform amplitude excitation are proposed and compared: phase tapering optimization (PTO) and a novel time-varying phase tapering (TPT). The PTO is a…

Signal Processing · Electrical Eng. & Systems 2024-07-09 Lior Maman , Shlomo Zach , Amir Boag