The nonlinearity inherent in the Traveling Wave Tube (TWT) amplifier distorts amplified signals and results in reduced efficiency and bandwidth, limiting its use in communication and electronic countermeasure applications. Signal predistortion is an effective technique for suppressing nonlinear distortion in TWTs that provides high suppression and requires simple circuits for implementation. Wh...

Using attosecond light pulses to doubly ionize a two-electron wave packet of helium, we showed that the time-resolved correlated motion of the two electrons can be probed by measuring their six-dimensional momentum distributions. For simple wave packets, we showed that the measured momenta, when analyzed in appropriate coordinates, can reveal the stretching, the rotational, and the bending vibr...

It is proposed that superoscillations play an important role in the interferences which give rise to superluminal effects. To exemplify that, we consider a toy model which allows for a wave packet to travel, in zero time and negligible distortion a distance arbitrarily larger than the width of the wave packet. The peak is shown to result from a superoscillatory superposition at the tail. Simila...

1 Optimality theorems for JL Yesterday we saw for MJL that we could achieve target dimension m = O(ε −2 log N), and for DJL we could achieve m = O(ε −2 log(1/δ)). The following theorems tell us that not much improvement is possible for MJL, and for DJL we have the optimal bound. Theorem 1 ([Alo03]). For any N > 1 and ε < 1/2, there exist N + 1 points in R N such that achieving the MJL guarantee...

It is proposed that superoscillations play an important role in the interferences that give rise to superluminal effects. To exemplify that, we consider a toy model that a wave packet to travel in zero time and negligible distortion, a distance arbitrarily larger than the width of the wave packet. The peak is shown to result from a superoscillatory superposition at the tail. Similar reasoning a...

Traditionally, static linearity and dynamic distortion tests are performed separately for ADCs. To this end, a low-frequency sinewave is histogrammed to measure static Integral Nonlinearity, and a high-frequency sine-wave is sampled for FFT processing to measure dynamic distortions and dynamic range. We propose to use a model-based technique to extract both static and dynamic nonlinearities fro...

We introduce a simple modification to the Z-scan technique that results in a sensitivity enhancement that permits measurement of nonlinearly induced wave-front distortion -of A/10 . This sensitivity was achieved with 10-Hz repetition-rate pulsed laser sources. Sensitivity to nonlinear absorption is also enhanced by a factor of -3. This method permits characterization of nonlinear thin films wit...

In "imaging the biomechanical properties of tissues," a number of approaches analyze shear wave propagation initiated by a short radiation force push. Unfortunately, it has been experimentally observed that the displacement-versus-time curves for lossy tissues are rapidly damped and distorted in ways that can confound simple tracking approaches. This article addresses the propagation, decay and...

In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been ...

In a two orbital double exchange model we formulate Jahn-Teller coupled charge density wave in half-filled limit. Softening of Jahn-Teller phonons corresponding to distortion modes Q2 or Q3 associated with perfect nesting of Fermi surface leads to this instability at low temperature. The gap equation for charge density wave state and its dependences on electron-lattice coupling are calculated e...