74 research outputs found
Experimental demonstration of a technique to generate arbitrary quantum superposition states
Using a single, harmonically trapped Be ion, we experimentally
demonstrate a technique for generation of arbitrary states of a two-level
particle confined by a harmonic potential. Rather than engineering a single
Hamiltonian that evolves the system to a desired final sate, we implement a
technique that applies a sequence of simple operations to synthesize the state
Inducing LIPSS by multi-pass and cross-directional scanning of femtosecond beam over surface of thin metal films
During interaction of femtosecond laser beam with metal surfaces, laser induced pe- riodic nanostructures, LIPSS can be formed, which may improve properties of materials. Having excellent mechanical properties, multilayer thin films, like 5x(Al/Ti)@Si, are con- venient for forming of high quality LIPSS [1] due to their multilayer structure. We have exposed the multilayer thin film metal systems 5x(Al/Ti)@Si with femtosecond beam from the laser system Coherent Mira 900 in NIR with various scanning configurations [2]. The irradiated samples have been analyzed by Tescan Mira3 SEM. The beam scanned over the surface of the samples with multi-pass and cross-directional scanning configurations with the change of polarization direction. The formation of LIPSS is most probably due to the occurence of surface plasmon polariton, which leads to the periodic distribution of energy on the sample surface. The orientation of the LIPSS is related to the direction of the beam polarization. During multi-pass scanning, LIPSS maintained its configuration. The preservation of structures occured to some extent. Depending on the accumulated energy, two forms of LIPSS were generated: “hills”, for less accumulation, and “trenches” for greater accumulation. “Hills” are non-ablative, probably are due to the build-up of the material and are parallel to the polarization direction. “Trenches” are formed by ablation and are perpendicular to the polarization direction. During cross-directional scanning, LIPSS of orthogonal directions have been generated. The value of the “hills” period was around 360 nm and the width was ∼285 nm. The values of “trenches” period fluctuated between 320 and 380 nm, while width was between 85 and 45 nm. Proposed mechanism is that, for less accumulated energy, “hills” formed, while more accumulated energy leads to the ablation and formation of “trenches”.UltrafastLight-2018 : International Conference on Ultrafast Optical Science : Book of Abstracts, October 1-5, 2018, Moscow, Russi
Trapped-Ion Quantum Simulator: Experimental Application to Nonlinear Interferometers
We show how an experimentally realized set of operations on a single trapped
ion is sufficient to simulate a wide class of Hamiltonians of a spin-1/2
particle in an external potential. This system is also able to simulate other
physical dynamics. As a demonstration, we simulate the action of an -th
order nonlinear optical beamsplitter. Two of these beamsplitters can be used to
construct an interferometer sensitive to phase shifts in one of the
interferometer beam paths. The sensitivity in determining these phase shifts
increases linearly with , and the simulation demonstrates that the use of
nonlinear beamsplitters (=2,3) enhances this sensitivity compared to the
standard quantum limit imposed by a linear beamsplitter (=1)
Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H
A model of the collisional kinetics of energetic hydrogen atoms, molecules,
and ions in pure H discharges is used to predict H emission
profiles and spatial distributions of emission from the cathode regions of
low-pressure, weakly-ionized discharges for comparison with a wide variety of
experiments. Positive and negative ion energy distributions are also predicted.
The model developed for spatially uniform electric fields and current densities
less than A/m is extended to non-uniform electric fields, current
densities of A/m, and electric field to gas density ratios MTd at 0.002 to 5 Torr pressure. (1 Td = V m and 1 Torr =
133 Pa) The observed far-wing Doppler broadening and spatial distribution of
the H emission is consistent with reactions among H, H,
H, and H ions, fast H atoms, and fast H molecules, and with
reflection, excitation, and attachment to fast H atoms at surfaces. The
H excitation and H formation occur principally by collisions of
fast H, fast H, and H with H. Simplifications include using a
one-dimensional geometry, a multi-beam transport model, and the average
cathode-fall electric field. The H emission is linear with current
density over eight orders of magnitude. The calculated ion energy distributions
agree satisfactorily with experiment for H and H, but are only in
qualitative agreement for H and H. The experiments successfully modeled
range from short-gap, parallel-plane glow discharges to beam-like,
electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201
Sympathetic cooling of and for quantum logic
We demonstrate the cooling of a two species ion crystal consisting of one
and one ion. Since the respective cooling transitions of
these two species are separated by more than 30 nm, laser manipulation of one
ion has negligible effect on the other even when the ions are not individually
addressed. As such this is a useful system for re-initializing the motional
state in an ion trap quantum computer without affecting the qubit information.
Additionally, we have found that the mass difference between ions enables a
novel method for detecting and subsequently eliminating the effects of radio
frequency (RF) micro-motion.Comment: Submitted to PR
Status and New Data of the Geochemical Determination of the pp-Neutrino Flux by LOREX
LOREX LORandite EXperiment addresses the determination of the solar pp neutrino flux during the last four million years by exploiting the reaction 205 Tl ν e → 205 Pb e − with an incomparably low-energy threshold of 50 keV for the capture of solar neutrinos. The ratio of 205 Pb/ 205 Tl atoms in the Tl-bearing mineral lorandite provides, if corrected for the cosmic-ray induced background, the product of the flux of solar neutrinos and their capture probability by 205 Tl, averaged over the age of lorandite. To get the mean solar neutrino flux itself, four problems have to be addressed: 1 the geological age of lorandite, 2 the amount of background cosmicray-induced 205 Pb atoms which strongly depends on the erosion rate of the lorandite-bearing rocks, 3 the capture probability of solar neutrinos by 205 Tl and 4 the extraction of lorandite and the appropriate technique to "count" the small number of 205 Pb atoms in relation to the number of 205 Tl atoms. This paper summarizes the status of items 1 age and 3 neutrino capture probability and presents in detail the progress achieved most recently concerning the items 2 background/erosion and 4 "counting" of 205 Pb atoms in lorandite
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