727 research outputs found
Information transfer by quantum matterwave modulation
Classical communication schemes that exploit wave modulation are the basis of
the information era. The transfer of information based on the quantum
properties of photons revolutionized these modern communication techniques.
Here we demonstrate that also matterwaves can be applied for information
transfer and that their quantum nature provides a high level of security. Our
technique allows transmitting a message by a non-trivial modulation of an
electron matterwave in a biprism interferometer. The data is encoded by a Wien
filter introducing a longitudinal shift between separated matterwave packets.
The transmission receiver is a delay line detector performing a dynamic
contrast analysis of the fringe pattern. Our method relies on the Aharonov-Bohm
effect and has no light optical analog since it does not shift the phase of the
electron interference. A passive eavesdropping attack will cause decoherence
and terminating the data transfer. This is demonstrated by introducing a
semiconducting surface that disturbs the quantum state by Coulomb interaction
and reduces the contrast. We also present a key distribution protocol based on
the quantum nature of the matterwaves that can reveal active eavesdropping
Progressive Replacement Grinding Technology
Import 05/08/2014Bakalářská práce se zabývá nahrazením broušení metodou přehlazování. V úvodu popisuji firmu V – NASS, a.s., odkud zadaný projekt vypracovávám. Dalším bodem je popis stávající technologie broušení. Cílem je teoretický rozbor a návrh nové technologie přehlazení.
Výsledkem této práce je ekonomické a technologické zhodnocení metody přehlazování i broušení. V závěru se obě metody porovnají a navrhne se řešení méně finančně nákladné.The bachelor thesis deals with the replacement of grinding method smoothing. The introduction describes the company V - NASS, and, where specified project compiled. Another point is the description of the existing grinding technology. The aim of the theoretical analysis and design of new technologies smoothing.
The result of this work is to evaluate the economic and technological methods smoothing and grinding. In conclusion, the two methods are compared and propose solutions less costly.346 - Katedra obrábění a montáževelmi dobř
A compact electron matter wave interferometer for sensor technology
Remarkable progress can be observed in recent years in the controlled
emission, guiding and detection of coherent, free electrons. Those methods were
applied in matter wave interferometers leading to high phase sensitivities and
novel sensor technologies for dephasing influences such as mechanical
vibrations or electromagnetic frequencies. However, the previous devices have
been large laboratory setups. For future sensor applications or tests of the
coherence properties of an electron source, small, portable interferometers are
required. Here, we demonstrate a compact biprism electron interferometer that
can be used for mobile applications. The design was optimized for small
dimensions by beam path simulations. The interferometer has a length between
the tip and the superposition plane before magnification of only 47 mm and
provides electron interference pattern with a contrast up to 42.7 %. The
detection of two dephasing frequencies at 50 and 150 Hz was demonstrated
applying second order correlation and Fourier analysis of the interference
data
Quantum interference with molecules: The role of internal states
Recent experiments have shown that fullerene and fluorofullerene molecules
can produce interference patterns. These molecules have both rotational and
vibrational degrees of freedom. This leads one to ask whether these internal
motions can play a role in degrading the interference pattern. We study this by
means of a simple model. Our molecule consists of two masses a fixed distance
apart. It scatters from a potential with two or several peaks, thereby
mimicking two or several slit interference. We find that in some parameter
regimes the entanglement between the internal states and the translational
degrees of freedom produced by the potential can decrease the visibility of the
interference pattern. In particular, different internal states correspond to
different outgoing wave vectors, so that if several internal states are
excited, the total interference pattern will be the sum of a number of
patterns, each with a different periodicity. The overall pattern is
consequently smeared out. In the case of two different peaks, the scattering
from the different peaks will excite different internal states so that the path
the molecule takes become entangled with its internal state. This will also
lead to degradation of the interference pattern. How these mechanisms might
lead to the emergence of classical behavior is discussed.Comment: 12 pages, 4 eps figures, quality of figures reduced because of size
restriction
A scalable optical detection scheme for matter wave interferometry
Imaging of surface adsorbed molecules is investigated as a novel detection
method for matter wave interferometry with fluorescent particles. Mechanically
magnified fluorescence imaging turns out to be an excellent tool for recording
quantum interference patterns. It has a good sensitivity and yields patterns of
high visibility. The spatial resolution of this technique is only determined by
the Talbot gratings and can exceed the optical resolution limit by an order of
magnitude. A unique advantage of this approach is its scalability: for certain
classes of nano-sized objects, the detection sensitivity will even increase
significantly with increasing size of the particle.Comment: 10 pages, 4 figure
- …