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Plasmon resonances are known to amplify the electromagnetic fields near metallic nanostructures. Therefore, they are considered to provide a promising scheme to generate extreme-ultraviolet harmonics, using low power drivings. During…

We study high order harmonics generation (HHG) in crystalline silicon and diamond subjected to near and mid-infrared laser pulses. We employ time-dependent density functional theory and solve the time-dependent Kohn-Sham equation in the…

Materials Science · Physics 2022-08-31 David Freeman , Shunsuke Yamada , Atsushi Yamada , Kazuhiro Yabana , Anatoli Kheifets

High-harmonic generation (HHG) involves the up-conversion of a high-intensity driving field into its harmonic orders. This process is intrinsically non-classical, requiring from quantum mechanics for a complete explanation as, under…

Quantum Physics · Physics 2024-09-25 Javier Rivera-Dean

In this paper, we investigate the effects of full electronic correlation on the high harmonic generation in the helium atom subjected to laser pulses of extremely high intensity. To do this, we perform real-time propagations of the helium…

Chemical Physics · Physics 2022-05-18 Aleksander P. Woźniak , Michał Przybytek , Maciej Lewenstein , Robert Moszyński

We calculate high-harmonic generation (HHG) by intense infrared lasers in atoms and molecules with the inclusion of macroscopic propagation of the harmonics in the gas medium. We show that the observed experimental spectra can be accurately…

For decades, most research on high harmonic generation (HHG) considered matter as quantum but light as classical, leaving the quantum-optical nature of the harmonics an open question. Here we explore the quantum properties of high…

Quantum Physics · Physics 2023-11-21 Matan Even Tzur , Michael Birk , Alexey Gorlach , Ido Kaminer , Michael Krueger , Oren Cohen

Attosecond pulses produced by High-order Harmonic Generation (HHG) in gases driven by intense laser fields have become a cornerstone technique for probing ultrafast electronic motion in matter. These applications require a good knowledge of…

High harmonic generation (HHG) in solids could enable attosecond and ultraviolet light sources with high compactness, great controllability and rich functions. However, the HHG process is accompanied by a quite large wavevector mismatch…

We present a variational augmentation procedure to optimize the exponents of Gaussian continuum basis sets for simulating strong-field laser ionization phenomena such as higher harmonic generation (HHG) in atoms and ions using the…

Chemical Physics · Physics 2023-07-04 Sai Vijay Bhaskar Mocherla , Raghunathan Ramakrishnan

The combination of high-order harmonic generation (HHG) with resonant XUV excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process is investigated theoretically. In this setup, the…

Atomic Physics · Physics 2023-01-10 Christian Buth , Markus C. Kohler , Joachim Ullrich , Christoph H. Keitel

The high harmonic generation from atoms in the combination of chirped laser pulse and static field is theoretically investigated. For the first time, we explore a further physical mechanism of the significant extension of high harmonic…

Optics · Physics 2015-05-13 Yang Xiang , Yueping Niu , Shangqing Gong

We perform a detailed analysis of how high-order harmonic generation (HHG) and above-threshold ionization (ATI) can be controlled by a time-delayed attosecond-pulse train superposed to a strong, near-infrared laser field. In particular we…

Atomic Physics · Physics 2009-11-11 C. Figueira de Morisson Faria , P. Salieres , P. Villain , M. Lewenstein

We propose and analyze a scheme for "on demand" creation of coherent superposition of meta-stable states in a tripod-structured atom using frequency-chirped laser pulses. Negligible excitation of the atoms during the creation of the…

Quantum Physics · Physics 2015-05-28 N. Sandor , J. S. Bakos , Zs. Sörlei , G. P. Djotyan

We present a theoretical demonstration on the generation of entangled coherent states and of coherent state superpositions, with photon numbers and frequencies orders of magnitude higher than those provided by the current technology. This…

An analytic study is presented of the efficient multiphoton excitation and strong harmonic generation in three-level systems specified by a pair of nearly degenerate, strongly dipole-coupled excited states. Such systems are physically…

Quantum Physics · Physics 2015-05-19 Michal Berent , Ryszard Parzyński

High harmonic generation (HHG) in gaseous media provides a robust method for producing coherent extreme-ultraviolet (EUV) radiation and attosecond pulses. However, the spectral and temporal properties of these pulses -- such as bandwidth…

The mechanism of harmonic generation in both O and X-mode configurations for a magnetized plasma has been explored here in detail with the help of Particle-In-Cell (PIC) simulations. A detailed characterization of both the reflected and…

Plasma Physics · Physics 2021-10-27 Srimanta Maity , Devshree Mandal , Ayushi Vashistha , Laxman Prasad Goswami , Amita Das

We present theoretical studies of high-order harmonic generation (HHG) produced by non-homogeneous fields as resulting from the illumination of plasmonic nanostructures with a short laser pulse. We show that both the inhomogeneity of the…

Atomic Physics · Physics 2012-04-27 M. F. Ciappina , J. Biegert , R. Quidant , M. Lewenstein

In strong field laser physics it is a common practice to use the high-order harmonic cutoff to estimate the laser intensity of the pulse that generates the harmonic radiation. Based on the semiclassical arguments it is possible to find a…

Atomic Physics · Physics 2015-06-11 T. Shaaran , M. F. Ciappina , M. Lewenstein

We experimentally observe longer than long trajectory influence in high order harmonic generation (HHG) by varying the peak intensity of the driving laser field through either direct attenuation, or by chirping the laser pulse. Using a…