The SCIENCE & TECHNOLOGY News Thread

[LoweGear]

Phys.org: Scientists create never-before seen matter

Originally Posted by Phys.org

Harvard and MIT scientists are challenging the conventional wisdom about light, and they didn't need to go to a galaxy far, far away to do it.

Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules – a state of matter that, until recently, had been purely theoretical. The work is described in a September 25 paper in Nature.

The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don't interact with each other – shine two laser beams at each other, he said, and they simply pass through one another.

"Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.

"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other," Lukin said. "What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn't been observed.

"It's not an in-apt analogy to compare this to light sabers," Lukin added. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."

To get the normally-massless photons to bind to each other, Lukin and colleagues, including Harvard post-doctoral fellow Ofer Fisterberg, former Harvard doctoral student Alexey Gorshkov and MIT graduate students Thibault

Peyronel and Qiu Liang couldn't rely on something like the Force – they instead turned to a set of more extreme conditions.


Researchers began by pumped rubidium atoms into a vacuum chamber, then used lasers to cool the cloud of atoms to just a few degrees above absolute zero. Using extremely weak laser pulses, they then fired single photons into the cloud of atoms.

As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.

"When the photon exits the medium, its identity is preserved," Lukin said. "It's the same effect we see with refraction of light in a water glass. The light enters the water, it hands off part of its energy to the medium, and inside it exists as light and matter coupled together, but when it exits, it's still light. The process that takes place is the same it's just a bit more extreme – the light is slowed considerably, and a lot more energy is given away than during refraction."

When Lukin and colleagues fired two photons into the cloud, they were surprised to see them exit together, as a single molecule.

The reason they form the never-before-seen molecules?

An effect called a Rydberg blockade, Lukin said, which states that when an atom is excited, nearby atoms cannot be excited to the same degree. In practice, the effect means that as two photons enter the atomic cloud, the first excites an atom, but must move forward before the second photon can excite nearby atoms.

The result, he said, is that the two photons push and pull each other through the cloud as their energy is handed off from one atom to the next.

"It's a photonic interaction that's mediated by the atomic interaction," Lukin said. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."

While the effect is unusual, it does have some practical applications as well.

"We do this for fun, and because we're pushing the frontiers of science," Lukin said. "But it feeds into the bigger picture of what we're doing because photons remain the best possible means to carry quantum information. The handicap, though, has been that photons don't interact with each other."

To build a quantum computer, he explained, researchers need to build a system that can preserve quantum information, and process it using quantum logic operations. The challenge, however, is that quantum logic requires interactions between individual quanta so that quantum systems can be switched to perform information processing.

"What we demonstrate with this process allows us to do that," Lukin said. "Before we make a useful, practical quantum switch or photonic logic gate we have to improve the performance, so it's still at the proof-of-concept level, but this is an important step. The physical principles we've established here are important."

The system could even be useful in classical computing, Lukin said, considering the power-dissipation challenges chip-makers now face. A number of companies – including IBM – have worked to develop systems that rely on optical routers that convert light signals into electrical signals, but those systems face their own hurdles.

Lukin also suggested that the system might one day even be used to create complex three-dimensional structures – such as crystals – wholly out of light.

"What it will be useful for we don't know yet, but it's a new state of matter, so we are hopeful that new applications may emerge as we continue to investigate these photonic molecules' properties," he said.

We're seeing the beginnings of Hard-Light here baby

[ganbaru]

Border's Mexicali tops Mexico City in pollution
http://hosted.ap.org/dynamic/stories...09-24-14-35-36

Amazon unveils Kindle Fire HDX with 24/7 live help
http://hosted.ap.org/dynamic/stories...09-25-16-28-10

[MrTerrorist]

A Sad Farewell To The Coolest Fighter Jet Of All Time

Looks like the USAF is finally retiring the A-10. That's sad.

Hopefully it will lead to this.

Empty F-16 jet tested by Boeing and US Air Force

[ganbaru]

Originally Posted by MrTerrorist

Empty F-16 jet tested by Boeing and US Air Force

I am surprised than they didn't do it before.

[Ithekro]

Originally Posted by ganbaru

I am surprised than they didn't do it before.

I'm pretty sure they did something like that with the F-4 Phanton II.

[AnimeFan188]

The First Carbon Nanotube Computer: The Hyper-Efficient Future Is Here:

"Coming just a year after the creation of the first carbon nanotube computer chip,
scientists have just built the very first actual computer with a central processor
centered entirely around carbon nanotubes. Which means the future of electronics just
got tinier, more efficient, and a whole lot faster."

See:

http://gizmodo.com/the-first-carbon-...ent-1387829179

[Jinto]

Sometimes I wonder if there is anything you cannot do with carbon nanotubes. It seems as if they are used almost everywhere to make things better, faster, more efficient.

[LoweGear]

Originally Posted by Jinto

Sometimes I wonder if there is anything you cannot do with carbon nanotubes. It seems as if they are used almost everywhere to make things better, faster, more efficient.

Carbon is magic. Nuff' said.

Also:

NBC News: First Mind-Controlled Bionic Leg a "Groundbreaking" Advance.

So first we had our bionic arms, and now bionic legs.... I totally asked for this

[ganbaru]

Originally Posted by Ithekro

I'm pretty sure they did something like that with the F-4 Phanton II.

Yes they did, but as the F16 have fly-by-wire flight control I thought than it would be easier to convert into a drone.

[Ithekro]

I would think remote drones would be fine for combat (as long as they aren't hacked or jammed). Entirely AI is something else for me.

[AnimeFan188]

Our Universe Might Just Be Fourth-Dimensional Black Hole Vomit:

"Scientists are proposing a radical new way of think about how the universe began. In
a new imagining of the Big Bang theory, they think it could have been the result of a
four-dimensional star collapsing in on itself to form a black hole, which then proceeded
to spew its guts out and, kindly, form our universe."

See:

http://gizmodo.com/our-universe-migh...hol-1410271260

[ganbaru]

France to sanction Google over privacy rules
http://hosted.ap.org/dynamic/stories...09-27-12-43-14

Climate panel forecast: Higher seas, temperatures
http://hosted.ap.org/dynamic/stories...09-27-18-29-52

[AnimeFan188]

Fusion, anyone?:

"The dream of igniting a self-sustained fusion reaction with high yields of energy, a
feat likened to creating a miniature star on Earth, is getting closer to becoming
reality, according the authors of a new review article in the journal Physics of
Plasmas.

Researchers at the National Ignition Facility (NIF) engaged in a collaborative project
led by the Department of Energy's Lawrence Livermore National Laboratory, report
that while there is at least one significant obstacle to overcome before achieving the
highly stable, precisely directed implosion required for ignition, they have met many
of the demanding challenges leading up to that goal since experiments began in
2010."

See:

http://www.spacedaily.com/reports/Fu...nyone_999.html


===================================

Thorium and inefficient solar power? That's good enough for me:

"The most cheering thing I've heard recently on this subject is that the price of
thorium is now positive. That might not mean much without explanation, so here
goes: There's thorium in all sorts of minerals from which we already extract
interesting metals. The tantalite and columbite that we make our capacitors from
for example: there's enough in the wastes from their processing that old factories
that used to do this are now Super Fund sites in the US."

"Lynas, which has built a new rare earths refinery in Malaysia, will have thorium
as a byproduct (there's always Th in your rare earth ores). They've announced
that they're getting offers to actually buy it from them: the price has turned
positive.

Now, OK, that's possibly only a matter of interest to metals geeks like myself: but
what it actually means is that someone, somewhere, is being serious about
starting up test runs of thorium reactors. It's the only possible use for the
material these days in any quantity."

See:

http://www.theregister.co.uk/2013/09...orium_reactor/

[Dr. Casey]

Originally Posted by Zakoo

It is above all a place to make children understand how society works that's why family teaching is always unadvised.

You mean homeschooling? By absolutely no means is homeschooling 'always unadvised.' There's plenty of ways for kids to receive their socialization and become perfectly well-adjusted individuals even if they're not sent to that damned hellhole for 13 years.

[Ithekro]

I remember going to Lawrance Livermore Labs back in I think 1990. There were just retirig their remaining Cray 2 supercomupters and working on laser indused Fusion with some results. They knew it worked, but could not get more power out of it than they put in, nor could they keep it going.

[Dr. Casey]

Yep, 1990 should be right. According to Wikipedia:

The Cray-2 was replaced as the world's fastest computer by the ETA-10G in 1990.

I should read up on Fusion more; it's touted as a miracle source of energy, but I know nothing about it besides the name.

[Ithekro]

Back then I thought those things were fast. Light speed computation that took a nano-second because that was how long the connector was from one part to another. At least that is how I remember them explaining it to us on their display model of the Cray-2 with its liquid cooled system.

[HasuMasu]

Originally Posted by Dr. Casey

Yep, 1990 should be right. According to Wikipedia:



I should read up on Fusion more; it's touted as a miracle source of energy, but I know nothing about it besides the name.

Stars are giant Nuclear Fusion Plants.

Nuclear Fusion on Earth would just that; an artificial star.

[Ithekro]

The question to me is, after you get a sustainable fusion...what forms do we use to access that energy to practical purposes? Solar cells around the new artificial star? boil water like we've been doing since the steam engine was invented? Or come up with something else? Something moe efficient? Something that will yield more power than at one instant than is currently possible with existing power generation plants (including fission reactor run safely)? Something to get that still unclaimed exotic matter to power up the Alcubierre drive (warp drive).

[HasuMasu]

Solar Cells would be alright; they're not cheap but once the star is born you have pseudo-free energy for a long time.