petehix

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Sat, 25 May 2013 12:44:26 +0100

astrodidact: Physicists Create Quantum Link Between Photons...

Sat, 25 May 2013 12:43:43 +0100

Physicists Create Quantum Link Between Photons That Don’t Exist at the Same Time

Now they’re just messing with us. Physicists have long known that quantum mechanics allows for a subtle connection between quantum particles called entanglement, in which measuring one particle can instantly set the otherwise uncertain condition, or “state,” of another particle—even if it’s light years away. Now, experimenters in Israel have shown that they can entangle two photons that don’t even exist at the same time.

“It’s really cool,” says Jeremy O’Brien, an experimenter at the University of Bristol in the United Kingdom, who was not involved in the work. Such time-separated entanglement is predicted by standard quantum theory, O’Brien says, “but it’s certainly not widely appreciated, and I don’t know if it’s been clearly articulated before.”

Entanglement is a kind of order that lurks within the uncertainty of quantum theory. Suppose you have a quantum particle of light, or photon. It can be polarized so that it wriggles either vertically or horizontally. The quantum realm is also hazed over with unavoidable uncertainty, and thanks to such quantum uncertainty, a photon can also be polarized vertically and horizontally at the same time. If you then measure the photon, however, you will find it either horizontally polarized or vertically polarized, as the two-ways-at-once state randomly “collapses” one way or the other.

Entanglement can come in if you have two photons. Each can be put into the uncertain vertical-and-horizontal state. However, the photons can be entangled so that their polarizations are correlated even while they remain undetermined. For example, if you measure the first photon and find it horizontally polarized, you’ll know that the other photon has instantaneously collapsed into the vertical state and vice versa—no matter how far away it is. Because the collapse happens instantly, Albert Einstein dubbed the effect “spooky action at a distance.” It doesn’t violate relativity, though: It’s impossible to control the outcome of the measurement of the first photon, so the quantum link can’t be used to send a message faster than light.

In standard entanglement swapping (top), entanglement (blue shading) is transferred to photons 1 and 4 by making a measurement on photons 2 and 3. The new experiment (bottom) shows that the scheme still works even if photon 1 is destroyed before photon 4 is created. Image: AAAS/Science

Now Eli Megidish, Hagai Eisenberg, and colleagues at the Hebrew University of Jerusalem have entangled two photons that don’t exist at the same time. They start with a scheme known as entanglement swapping. To begin, researchers zap a special crystal with laser light a couple of times to create two entangled pairs of photons, pair 1 and 2 and pair 3 and 4. At the start, photons 1 and 4 are not tangled. But they can be if physicists play the right trick with 2 and 3.

The key is that a measurement “projects” a particle into a definite state — just as the measurement of a photon collapses it into either vertical or horizontal polarization. So even though photons 2 and 3 start out unentangled, physicists can set up a “projective measurement” that asks, are the two in one of two distinct entangled states or the other? That measurement entangles the photons, even as it absorbs and destroys them. If the researchers select only the events in which photons 2 and 3 end up in, say, the first entangled state, then the measurement also entangles photons 1 and 4. (See diagram, top.) The effect is a bit like joining two pairs of gears to form a four-gear chain: Enmeshing two inner gears establishes a link between the outer two.

In recent years, physicists have played with the timing in the scheme. For example, last year a team showed that entanglement swapping still works even if they make the projective measurement after they’ve already measured the polarizations of photons 1 and 4. Now, Eisenberg and colleagues have shown that photons 1 and 4 don’t even have to exist at the same time, as they report in a paper in press at Physical Review Letters.

To do that, they first create entangled pair 1 and 2 and measure the polarization of 1 right away. Only after that do they create entangled pair 3 and 4 and perform the key projective measurement. Finally, they measure the polarization of photon 4. And even though photons 1 and 4 never coexist, the measurements show that their polarizations still end up entangled. Eisenberg emphasizes that even though in relativity, time measured differently by observers traveling at different speeds, no observer would ever see the two photons as coexisting.

The experiment shows that it’s not strictly logical to think of entanglement as a tangible physical property, Eisenberg says. “There is no moment in time in which the two photons coexist,” he says, “so you cannot say that the system is entangled at this or that moment.” Yet, the phenomenon definitely exists. Anton Zeilinger, a physicist at the University of Vienna, agrees that the experiment demonstrates just how slippery the concepts of quantum mechanics are. “It’s really neat because it shows more or less that quantum events are outside our everyday notions of space and time.”

So what’s the advance good for? Physicists hope to create quantum networks in which protocols like entanglement swapping are used to create quantum links among distant users and transmit uncrackable (but slower than light) secret communications. The new result suggests that when sharing entangled pairs of photons on such a network, a user wouldn’t have to wait to see what happens to the photons sent down the line before manipulating the ones kept behind, Eisenberg says. Zeilinger says the result might have other unexpected uses: “This sort of thing opens up people’s minds and suddenly somebody has an idea to use it in quantum computing or something.”

This story provided by ScienceNOW, the daily online news service of the journal Science.

http://www.wired.com/wiredscience/2013/05/quantum-linked-photons/

beesandbombs: orbiters

Sat, 25 May 2013 12:34:26 +0100

beesandbombs:

orbiters

fuckeverythingbecomeapirate: “Any ideas for the new park...

Sat, 25 May 2013 12:30:49 +0100

fuckeverythingbecomeapirate:

“Any ideas for the new park sculpture?”

“How about a giant, metallic octopus attacking a rook?”

“Perfect.”

Beautiful if you ask me

smashingdevotchka: saltineofswing: joonssound: the animator...

Fri, 24 May 2013 22:04:23 +0100

smashingdevotchka:

saltineofswing:

joonssound:

the animator probably requested that this be put in the script because they were so excited that the boulder came out as great as it did so he wanted a little reward for himself… at least, that’s what I would have done…

Maybe they had a ton of trouble rendering the boulder properly and so when it was done they were like ‘You know what? This shit deserves a line in the script.’

As the daughter of a renderer, I can confirm this is pretty likely. :P

Photo

Fri, 24 May 2013 22:03:35 +0100

erinisprettycool: i forgot how amazing it feels to just run around in the sunshine ^^ England,...

Fri, 24 May 2013 21:17:19 +0100

erinisprettycool:

i forgot how amazing it feels to just run around in the sunshine ^^

England, that one time it was sunny

thehealthylifeofme: gameplate: Minecraft comic series...

Fri, 24 May 2013 20:51:09 +0100

thehealthylifeofme:

gameplate:

Minecraft comic series by

Alexander Diochon

OMG! so cool!!

thenewenlightenmentage: The First Image Ever of a Hydrogen...

Fri, 24 May 2013 20:49:01 +0100

thenewenlightenmentage:

The First Image Ever of a Hydrogen Atom’s Orbital Structure

What you’re looking at is the first direct observation of an atom’s electron orbital — an atom’s actual wave function! To capture the image, researchers utilized a new quantum microscope — an incredible new device that literally allows scientists to gaze into the quantum realm.

An orbital structure is the space in an atom that’s occupied by an electron. But when describing these super-microscopic properties of matter, scientists have had to rely on wave functions — a mathematical way of describing the fuzzy quantum states of particles, namely how they behave in both space and time. Typically, quantum physicists use formulas like the Schrödinger equation to describe these states, often coming up with complex numbers and fancy graphs.

Continue Reading

tiredtalk: disgustinghuman: Scientist takes off clothes to go...

Fri, 24 May 2013 16:23:00 +0100

tiredtalk:

disgustinghuman:

Scientist takes off clothes to go swimming with belugas. In the wild they will not interact with people wearing clothes.

me either

“NEITHER DO I”

/pain

Why is there a police car? :c can’t a man play his drums...

Fri, 24 May 2013 15:27:07 +0100

Why is there a police car? :c can’t a man play his drums in peace?

Why is there a police car? :c can’t a man play his drums...

Fri, 24 May 2013 15:27:07 +0100

Why is there a police car? :c can’t a man play his drums in peace?

http://youtu.be/XsyLBxY-Sik

Fri, 24 May 2013 13:01:00 +0100

http://youtu.be/XsyLBxY-Sik

townsvillain: is pronounced gif or j- gunshots screaming junshots*

Fri, 24 May 2013 09:44:31 +0100

townsvillain:

is pronounced gif or j- *gunshots* *screaming*

junshots*

tinydragongina: Mam*

Fri, 24 May 2013 09:19:03 +0100

tinydragongina:

Mam*

SLEEPY BOYS ARE THE WORST AND BY WORST I MEAN ABSOLUTE BEST BECAUSE ADORABLE MESSY HAIR AND RASPY...

Thu, 23 May 2013 21:50:34 +0100

SLEEPY BOYS ARE THE WORST AND BY WORST I MEAN ABSOLUTE BEST BECAUSE ADORABLE MESSY HAIR AND RASPY VOICES AND POUTY LIPS I JUST CANT DEAL WITH THIS.

So THAT’S why Corrie always wakes me up in the morning, waits for me to fall asleep again anD THEN WAKES ME UP AGAIN, REPEATEDLY

n-a-s-a: Red Sprite Lightning with Aurora Image Credit &...

Thu, 23 May 2013 21:45:06 +0100

n-a-s-a:

Red Sprite Lightning with Aurora

Image Credit & Copyright: Walter Lyons (FMA Research)

So, I watched a film with this guy in it the other day. Let me...

Thu, 23 May 2013 21:44:58 +0100

So, I watched a film with this guy in it the other day.

Let me just tell you

I get it,

Photo

Thu, 23 May 2013 21:44:28 +0100

folie-a-tout: heyaeya: dameofspace: pandyssian: OH MY GOD APPARENTLY TAKING AN ARROW TO THE KNEE...

Thu, 23 May 2013 21:40:19 +0100

folie-a-tout:

heyaeya:

dameofspace:

pandyssian:

OH MY GOD APPARENTLY TAKING AN ARROW TO THE KNEE WAS AN OLD NORDIC SLANG FOR GETTING MARRIED

I THOUGHT THAT ALL THOSE GUYS IN SKYRIM HAD LITERALLY BEEN SHOT IN THEIR KNEES WITH ARROWS BUT I GUESS NOT

And at that moment, the foundation of that entire meme became something like this:

THAT EXPLAINS WHY MEN GO DOWN ON ONE KNEE WHEN THEY PROPOSE

OH MY GOD