12,020 research outputs found
EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment
After a very brief review of the historical Einstein, Podolsky, and Rosen (EPR) experiments, a new two-photon interference type EPR experiment is reported. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First and second order interference effectors were studied. Different than other reports, we observed that the second order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences
Steady-state entanglement in a double-well Bose-Einstein condensate through coupling to a superconducting resonator
We consider a two-component Bose-Einstein condensate in a double-well
potential, where the atoms are magnetically coupled to a single-mode of the
microwave field inside a superconducting resonator. We find that the system has
the different dark-state subspaces in the strong- and weak-tunneling regimes,
respectively. In the limit of weak tunnel coupling, steady-state entanglement
between the two spatially separated condensates can be generated by evolving to
a mixture of dark states via the dissipation of the photon field. We show that
the entanglement can be faithfully indicated by an entanglement witness.
Long-lived entangled states are useful for quantum information processing with
atom-chip devices.Comment: 9 pages, 7 figures, minor revisio
Dispersion spreading of polarization-entangled states of light and two-photon interference
We study the interference structure of the second-order intensity correlation
function for polarization-entangled two-photon light obtained from type-II
collinear frequency-degenerate spontaneous parametric down-conversion (SPDC).
The structure is visualised due to the spreading of the two-photon amplitude as
two-photon light propagates through optical fibre with group-velocity
dispersion (GVD). Because of the spreading, polarization-entangled Bell states
can be obtained without any birefringence compensation at the output of the
nonlinear crystal; instead, proper time selection of the intensity correlation
function is required. A birefringent material inserted at the output of the
nonlinear crystal (either reducing the initial o-e delay between the oppositely
polarized twin photons or increasing this delay) leads to a more complicated
interference structure of the correlation function.Comment: Extended version of our recent PRL paper. Submitted to PR
Coherent control of atomic spin currents in a double well
We propose an experimental feasible method for controlling the atomic
currents of a two-component Bose-Einstein condensate in a double well by
applying an external field to the atoms in one of the potential wells. We study
the ground-state properties of the system and show that the directions of spin
currents and net-particle tunneling can be manipulated by adiabatically varying
the coupling strength between the atoms and the field. This system can be used
for studying spin and tunneling phenomena across a wide range of interaction
parameters. In addition, spin-squeezed states can be generated. It is useful
for quantum information processing and quantum metrology.Comment: 6 pages, 7 figures, minor revisio
Study of fatigue durability of advanced composite materials under conditions of accelerated loading
The effect of temperature on the tension-tension fatigue life of the T300/5208 graphite/epoxy angle-ply laminate system was investigated in an effort to develop an acceptable and reliable method of accelerated loading. Typical S log sub 10 N curves were determined experimentally at 25 C, 75 C, and 115 C. The time-temperature superposition principle was employed to find the shift factors of uniaxial fatigue strength, and a general linear equation of S log sub 10 N for shifting purpose was established. The combined techniques of cyclic creep measurements and optical microscopy upon fatigue failure allow some assessment of the possible physical basis of S log 10 N curve shifting. Before fatigue, the laminates at all test temperatures and stress levels undergo a unique damage mechanism during fatigue loading. It is concluded that an accelerated loading method is feasible
Two-photon interference with thermal light
The study of entangled states has greatly improved the basic understanding
about two-photon interferometry. Two-photon interference is not the
interference of two photons but the result of superposition among
indistinguishable two-photon amplitudes. The concept of two-photon amplitude,
however, has generally been restricted to the case of entangled photons. In
this letter we report an experimental study that may extend this concept to the
general case of independent photons. The experiment also shows interesting
practical applications regarding the possibility of obtaining high resolution
interference patterns with thermal sources.Comment: Added reference 1
GEMINI: A Generic Multi-Modal Natural Interface Framework for Videogames
In recent years videogame companies have recognized the role of player
engagement as a major factor in user experience and enjoyment. This encouraged
a greater investment in new types of game controllers such as the WiiMote, Rock
Band instruments and the Kinect. However, the native software of these
controllers was not originally designed to be used in other game applications.
This work addresses this issue by building a middleware framework, which maps
body poses or voice commands to actions in any game. This not only warrants a
more natural and customized user-experience but it also defines an
interoperable virtual controller. In this version of the framework, body poses
and voice commands are respectively recognized through the Kinect's built-in
cameras and microphones. The acquired data is then translated into the native
interaction scheme in real time using a lightweight method based on spatial
restrictions. The system is also prepared to use Nintendo's Wiimote as an
auxiliary and unobtrusive gamepad for physically or verbally impractical
commands. System validation was performed by analyzing the performance of
certain tasks and examining user reports. Both confirmed this approach as a
practical and alluring alternative to the game's native interaction scheme. In
sum, this framework provides a game-controlling tool that is totally
customizable and very flexible, thus expanding the market of game consumers.Comment: WorldCIST'13 Internacional Conferenc
Induced Coherence and Stable Soliton Spiraling
We develop a theory of soliton spiraling in a bulk nonlinear medium and
reveal a new physical mechanism: periodic power exchange via induced coherence,
which can lead to stable spiraling and the formation of dynamical two-soliton
states. Our theory not only explains earlier observations, but provides a
number of predictions which are also verified experimentally. Finally, we show
theoretically and experimentally that soliton spiraling can be controled by the
degree of mutual initial coherence.Comment: 4 pages, 5 figure
Comment on ``Dispersion-Independent High-Visibility Quantum Interference ... "
We show in this Comment that the interpretation of experimental data as well
as the theory presented in Atat\"ure et al. [Phys. Rev. Lett. 84, 618 (2000)]
are incorrect and discuss why such a scheme cannot be used to "recover"
high-visibility quantum interference.Comment: Comment on Atat\"ure et al. [Phys. Rev. Lett. 84, 618 (2000)], 2nd
revision, To appear in Phys. Rev. Lett. April, (2001
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