Related papers: Interrogating the temporal coherence of EUV freque…
We present the first unambiguous detection of quasi-periodic wave trains within the broad pulse of a global EUV wave (so-called "EIT wave") occurring on the limb. These wave trains, running ahead of the lateral CME front of 2-4 times…
We present a new method for generating a regular train of ultrashort optical pulses in a prepared two-level medium. The train develops from incident monochromatic probe radiation travelling in a medium of atoms, which are in a quantum…
A general mechanism for the generation of frequency combs referenced to atomic resonances is put forward. The mechanism is based on the periodic phase control of a quantum system's dipole response. We develop an analytic description of the…
A theoretical analysis is carried out for the recently developed three-pulse photon echo spectroscopy employing dual frequency combs (DFC) as the light sources. In this method, the molecular sample interacts with three pulse trains derived…
Controlling nonequilibrium dynamics in quantum materials requires ultrafast probes with spectral selectivity. We report femtosecond reflectivity measurements on the cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ using…
This work theoretically investigates high-order harmonic generation in rare gas atoms driven by two temporally delayed ultrashort laser pulses. Apart from their temporal delay, the two pulses are identical. Using a single-atom model of the…
Physical systems with co-existence and interplay of processes featuring distinct spatio-temporal scales are found in various research areas ranging from studies of brain activity to astrophysics. Complexity of such systems makes their…
The ongoing development of intense high-harmonic generation (HHG) sources has recently enabled highly nonlinear ionization of atoms by the absorption of at least 10 extreme-ultraviolet (XUV) photons within a single atom [Senfftleben…
Data obtained by the Extreme Ultraviolet Explorer satellite are used to determine the EUV spectrum of the quasi-coherent oscillations of the dwarf nova SS Cygni. It is found that the spectrum of the oscillations is neither blue nor red nor…
Nonstationary molecular states which contain electronic coherences can be impulsively created and manipulated by using recently-developed ultrashort optical and X-ray pulses via photoexcitation, photoionization and Auger processes. We…
The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences…
It has been found that noise-induced excitability in quantum well and quantum dot semiconductor laser systems usually produces spike patterns of non-uniform amplitude. In this letter, we experimentally record that an inter-subband quantum…
Optical frequency combs based on mode-locked lasers have revolutionized many areas of science and technology, such as precision metrology, optical frequency synthesis or telecommunications. In recent years, a particular kind of frequency…
We demonstrate the use of a femtosecond frequency comb to coherently drive stimulated Raman transitions between terahertz-spaced atomic energy levels. More specifically, we address the $3d~^2D_{3/2}$ and $3d~^2D_{5/2}$ fine structure levels…
We explore self-induced parametric coupling, also called internal resonances (IRs), in a membrane nanoelectromechanical system. Specifically, we focus on the formation of a limit cycle manifesting as a phononic frequency comb. Utilizing a…
Coherent supercontinuum radiation in the extreme-ultraviolet (XUV) range is indispensable for synthesizing attosecond light pulses and for exploring transient atomic structures. Here, we report the striking observations of coherent XUV…
We present spatial coherence measurements of extreme-ultraviolet light generated using the process of high-harmonic upconversion of a femtosecond laser. Using a phase-matched hollow-fiber geometry, the generated beam is found to exhibit…
Electro-optic frequency combs with tooth spacings as low as 100 Hz were employed to probe electromagnetically induced transparency (EIT) and hyperfine pumping in rubidium and potassium vapor cells. From the potassium EIT transition we were…
In this article, we derive analytically the complex optical spectrum of a pulsed laser source obtained when a frequency comb generated by phase modulation is input into a synchronized intensity modulator. We then show how this knowledge of…
We present a method to distinguish the high harmonics generated in individual half-cycle of the driving laser pulse by mixing a weak ultraviolet pulse, enabling one to observe the cutoff of each half-cycle harmonic. We show that the detail…