Group items tagged

Filter: All | Bookmarks | Topics Simple Middle

shared by Jac Londe on 25 Apr 11 - No Cached

Scientists have demonstrated for the first time that atoms can be guided in a laser beam and possess the same properties as light guided in an optical communications fiber.
...

Cancel
Abstract Speckle patterns produced by multiple independent light sources are a manifestation of the coherence of the light field. Second-order correlations exhibited in phenomena such as photon bunching, termed the Hanbury Brown–Twiss effect, are a measure of quantum coherence. Here we observe for the first time atomic speckle produced by atoms transmitted through an optical waveguide, and link this to second-order correlations of the atomic arrival times. We show that multimode matter-wave guiding, which is directly analogous to multimode light guiding in optical fibres, produces a speckled transverse intensity pattern and atom bunching, whereas single-mode guiding of atoms that are output-coupled from a Bose–Einstein condensate yields a smooth intensity profile and a second-order correlation value of unity. Both first- and second-order coherence are important for applications requiring a fully coherent atomic source, such as squeezed-atom interferometry.
...

Cancel
Australian National University
...

Cancel

shared by Jac Londe on 29 Nov 11 - No Cached

At a quantum scale, the motion of electrons and protons is completely and genuinely random, since it doesn’t follow a clear path of cause and effect. You basically have no idea what’s going to happen. If you can measure this somehow, than you’ve got yourself an absolutely random value.
...

Cancel
“If you want to defeat an adversary who is trying to hack into your system, basically you need large quantities of random numbers,”  Sussman said.
...

Cancel
“…a truly random number generator will provide impenetrable encryption for communications — be they military transmissions, secure banking, or online purchasing — that underpin the modern connected world.”
...

Cancel
...3 more annotations...
The researchers used pulses of laser light, which only last a trillionth of a second, that were directed through a diamond. The light comes and goes through the diamond, however when it exists it’s changed, since it has to pass through quantum vacuum fluctuations, the microscopic flickering of the amount of energy in a point in space. Scientists can measure these pulses of light that emerge from the experimental set-up, measurements which are the truly random.
...

Cancel
random numbers
...

Cancel
with quantum physics
...

Cancel

shared by Jac Londe on 25 Oct 10 - No Cached

first direct images of
...

Cancel
magnetic monopoles
...

Cancel
Image representing 12 micrometer x 12 micrometer of artificial magnetic metamaterial where monopoles can be seen at each end of the Dirac strings, visible as dark lines. The dark regions correspond to magnetic islands where the magnetization is reversed. (Image courtesy of Paul Scherrer Institute)
...

Cancel
...3 more annotations...
“A magnetic monopole is a ‘hypothetical’ particle that is a magnet with only one single magnetic pole,” says UCD Theoretical Physicist, Professor Hans-Benjamin Braun from the UCD School of Physics, who co-led the study with Dr Laura Heyderman from the Paul Scherrer Institute in Switzerland.
...

Cancel
“Some of the most important theories explaining how quantum matter behaves in the universe are based on their existence, but they have eluded direct imaging since they were first theoretically conceived in the 1930s.”
...

Cancel
Initially conceived by the British-Swiss theoretical physicist Dirac in 1931, monopoles were proposed to occur as emergent quasiparticles in so called pyrochlore spin-ice systems by Castelnovo, Moessner and Sondhi in 2008.
...

Cancel

shared by Jac Londe on 24 Mar 15 - No Cached

1 - 4 of 4

Showing 20▼ items per page