Skip navigation
Help

Quantum mechanics

warning: Creating default object from empty value in /var/www/vhosts/sayforward.com/subdomains/recorder/httpdocs/modules/taxonomy/taxonomy.pages.inc on line 33.
Original author: 
Soulskill

schirra writes "The MIT Game Lab has just released the graphics/physics engine from its popular game A Slower Speed of Light as an open-source project, allowing anyone to play around with the effects of special relativity using Unity3D. While the hope is that game developers and educators will use OpenRelativity to develop new kinds of relativistic games and simulations, that shouldn't stop those with a casual interest from playing around with these wicked cool effects. For the physics inclined, these effects include Lorentz contraction, time dilation, Doppler shift, and the searchlight effect--though a PhD in theoretical physics isn't required to enjoy or use the project."

Share on Google+

Read more of this story at Slashdot.

0
Your rating: None
Original author: 
John Timmer


The D-Wave Two.

D-Wave

D-Wave's quantum optimizer has found a new customer in the form of a partnership created by Google, NASA, and a consortium of research universities. The group is forming what it's calling the Quantum Artificial Intelligence Lab and will locate the computer at NASA's Ames Research Center. Academics will get involved via the Universities Space Research Association.

Although the D-Wave Two isn't a true quantum computer in the sense the term is typically used, D-Wave's system uses quantum effects to solve computational problems in a way that can be faster than traditional computers. How much faster? We just covered some results that indicated a certain class of problems may be sped up by as much as 10,000 times. Those algorithms are typically used in what's termed machine learning. And machine learning gets mentioned several times in Google's announcement of the new hardware.

Machine learning is typically used to allow computers to classify features, like whether or not an e-mail is spam (to use Google's example) or whether or not an image contains a specific feature, like a cat. You simply feed a machine learning system enough known images with and without cats and it will identify features that are shared among the cat set. When you feed it unknown images, it can determine whether enough of those features are present and make an accurate guess as to whether there's a cat in it. In more serious applications machine learning has been used to identify patterns of brain activity that are associated with different visual inputs, like viewing different letters.

Read 1 remaining paragraphs | Comments

0
Your rating: None
Original author: 
Carl Franzen

Quantum-smartcard-qkard-los-alamos_large

It's not quite a quantum internet — yet. But researchers at Los Alamos National Laboratory in New Mexico have developed a new, ultra-secure computer network that is capable of transmitting data that has been encrypted by quantum physics, including video files. The network, which currently consists of a main server and three client machines, has been running continuously in Los Alamos for the past two and a half years, the researchers reported in a paper released earlier this month. During that time, they have also successfully tested sending critical information used by power companies on the status of the electrical grid. Eventually they hope to use it to test offline quantum communication capabilities on smartphones and tablets.

Continue reading…

0
Your rating: None
Original author: 
Carl Franzen

Quantum-key-distribution-airplane_large

In a boost to future secret agents and a blow to their would-be eavesdroppers, German researchers report sending the first successful quantum communications from a moving source — an airplane traveling 180 miles-per-hour — to a stationary receiver on the ground. The study was first performed in 2012 but the results were just made public over the weekend in the journal Nature Photonics.

Continue reading…

0
Your rating: None

Physicist: The wave-like property of particles allows you to do a lot of cute things with particles that would otherwise seem impossible, but making a particle disappear isn’t one of them.  You can use destructive interference to make it very unlikely to find a particle in particular places, which is exactly what’s happening in the double slit experiment, and is also the basis behind how “diffraction gratings” work.

Lasers are one of the big reasons to go into physics.  Sure, there's the whole "understanding the nature of reality" thing, but it's mostly about lasers.

The wave nature of things (in this case light) can be used to get it to go places it normally wouldn’t (right), or not go places it normally would (left).  By using two slits you can interfere the light waves to cause the light to never show up in places where it would when passing through one slit (dark bands in in the lower left).

But in order to destroy a particle using destructive interference you’d need to ensure that there was nowhere left with any constructive interference.  In the pictures above there are dark regions, but also light regions.  Turns out there are some very solid mathematical principles and physical laws that don’t allow waves to behave that way (not just waves in particle physics, but waves in general), not the least of which is the conservation of energy.  So, say you’ve got some kind of waves bouncing around (light waves, sound waves, particle fields, whatever), and you want to make new waves to cancel them out.  You can certainly do that, but only in small regions.

If everyone on the air plane just turned off their noise-cancelling headphones, then the flight would be almost silent.

How noise canceling headphones work.  Rather than destroying sound around them, they cancel out the sound on one side that’s coming from the other.  But ultimately they’re just speakers that make the environment louder overall.

The new waves add energy to the overall system, so no matter how hard you try to cancel things out, you’ll always end up adding energy somewhere, it’s just a question of where.  Noise canceling headphones are a beautiful example.  They actively produce sound in such a way that they destructively interfere with sound waves coming from nearby, in the anti-headward direction.  Although they create quiet in the ears, they create noise everywhere else.  There’s no getting around it.

Yes; this is art.

Say you’ve got a bunch of noise bouncing about.  Noise canceling techniques can create a quite region, but end up generating more total noise outside of that region.

Similarly, you could try to kill off particles by creating new waves in the particles field (each kind of particle has a corresponding field, for example light particles are called “photons” and they have the electromagnetic field) that cancel out the particle.  You can totally create a particle “dead zone”, assuming you know exactly what the particle’s wave form is.  Headphones need this as well; you can’t just get rid of sound, you first need to know exactly what the sound is first.  However, anything you try will end up adding more particles , and won’t destroy the particle you’re worried about anyway, just redirect it.

There are a few ways to destroy a particle.  You can chuck it out (which is as good as destroying it, for most practical purposes), or you can annihilate it.  But annihilation is a bit of a cheat; you just put a particle in a chamber with its anti-particle and let nature take its course.  But that doesn’t use waves and interference (in the way we normally think of waves), they just combine, disappear, and leave behind a burst of energy.  But not in a cool, wavey interferey, kind of way.

The pictures at the top of this post are from here and here.

0
Your rating: None

The Shor algorithm works perfectly (gives you a useful value of k) more than 40% of the time.  That may not sound great.  But if it doesn’t work the first time, why not try it a few thousand more times?  On a quantum computer, this algorithm is effectively instantaneous.

I left a couple of details out of the math here because, frankly, this post is a little over the top.  If you read all the way to here, buy yourself a drink and take a nap.  However, if you’re interested in exactly why you need N>M2, how execute the quantum Fourier transform, and why the algorithm works better than 40% of the time, then there are some rough notes in this pdf: Shor.

A commenter pointed out that the equations in this post may not be showing up for everyone.  In partial remedy, here’s a pdf of the above post: quantum_RSA_Shor.

4
Your rating: None Average: 4 (1 vote)

MrSeb writes "Today's groundbreaking entry into the Uncanny Valley is a pair of mechanical, robot legs that are propelled entirely by their own weight: they can walk with a human-like gait without motors or external control. Produced by some researchers at Nagoya Institute of Technology in Japan, all the legs require for sustained motion (they walked 100,000 steps, 15km, over 13 hours last year) is a gentle push and a slight downwards slope. They then use same 'principle of falling' that governs human walking, with the transfer of weight (and the slight pull of gravity), pulling the robot into consecutive steps."

Read more of this story at Slashdot.

0
Your rating: None

Quantum GIS (QGIS) is a user friendly Open Source Geographic Information System (GIS) licensed under the GNU General Public License. QGIS is an official project of the Open Source Geospatial Foundation (OSGeo). It runs on Linux, Unix, Mac OSX, and Windows and supports numerous vector, raster, and database formats and functionalities.

Our latest release is QGIS 1.7.0 - you can read the release annoucement here.

0
Your rating: None

Enjoy a spectacular particle storm! In this experiment
we use a bitmap filled with Perlin noise to create
an acceleration field. The field controls the motion of thousands
of particles creating a turbulent, dramatic effect.
We use filters and color transforms to obtain the effect
of fading trails behind the churning particles.
Complete source code available for download.

0
Your rating: None