Single-atom Laser Built at Caltech

hweimer writes "A research group at Caltech has successfully constructed a laser consisting of only one caesium atom. The emitted light is very weak but highly ordered, so such a device may be used to control a quantum computer. More on this can be found at PhysicsWeb."

GoogleNews

[Leffe]

Here's a handy link with all the articles on GoogleNews:

http://news.google.com/news?q=single+atom+laser [google.com]

How does this fit with Quantum computing

[fruey]

(Blatantly stolen from link on the right of the article)

A system with one or more individual atoms at rest and strongly coupled to a single mode of the electromagnetic field is ideal for testing fundamental concepts of quantum computing and quantum information processing (see Physics World 1998 March). Indeed, Scott Parkins, now at the University of Auckland, and collaborators at the JILA Laboratory in Boulder, Colorado, and Caltech first proposed this system as a highly efficient quantum interface in 1993. Using the strong coupling of an atom to a single photon, it should be possible to map a quantum bit at rest from an atomic medium onto a propagating light field, and vice versa. In other words, this scheme could allow quantum information to be sent from one place to another. The first experimental results in this direction were obtained very recently by Markus Hennrich and co-workers at the MPQ. Moreover, two atoms in the cavity should make it possible to realize a "controlled NOT gate", the elementary building block of a quantum computer.

But it does answer the question I was asking myself...

Re:Begging the question:

[SheldonYoung]

It's a reference to the movie Austin Powers: Goldmember. Scottie gives his dad, Dr. Evil, "sharks with frickin' laser beams on their heads" in an attempt to win his affection.

Re:Begging the question:

[Anonymous Coward]

austin powers 1 was where that joke started, not austin powers 3.

Re:Not big enough.

[Thud457]

Here you go... [achilles.net]

Quantum computers exist already

[Hittite Creosote]

We already have quantum computers [ibm.com]. They've been used to factor the number 15! Woo!

Well, you've got to start from somewhere...

Re:Wow

[__aagmrb7289]

Since I've had two replies that basically say the same thing, I'll reply to myself to answer:

1. Of course it isn't easy; and
2. This is a tool that quantum computer researchers have pretty much been requesting - a laser to more easily manipulate the devices they currently are using.

Point is, this isn't some obscure, not so useful (yet) tool - it has immediate applications, and can be put to immediate use.

Re:construction

[mpe]

The cesium atom is just like the ruby from a ruby laser.

Except that active part of a ruby laser are chromium ions.

There are other components, including, according to the article, at least two OTHER laseres, presumably of the multi-atom variety. So that begs the question: Is it really an accomplishment when you use two lasers to make a WEAKER laser?

The monochromatic light from a laser is the result of an electron moving to a lower energy state. In order for this to happen it first needs to have been moved to a higher energy state. This is presumably what the other 2 lasers are doing.

usefulness in quantum computing?

[sluke]

Off the top of my head I can think of two areas where this could be useful for quantum computing. The first would be as a way to comvert flying qubits (photons) in to stationary qubits. If this could be done, than technology such as quantum repeaters would be possible, therefore allowing for long distance quantum cryptography. The second would be as a single photon source, which would have big applications in optical quantum computing.

The article, however, was very light on specifics. It says that the light exhibits antibunching, yet calls it a laser. My understanding of coherent states was that the probability of sending out two photons was high enough that it causes problems with quantum cryptography (Eve can simply observe one of the flying qubits and let the other one go). So do they envision using this as a single photon source? I haven't had a chance to read the journal article yet, so if someone who has a little more info could clarify I would be quite appreciative.

Re:Wow

[__aagmrb7289]

Okay, damn. Thought the average reader kept up with technology news. THEY ARE, AND HAVE, BUILT "QUANTUM COMPUTERS". They don't work well, and are very simplistic at this point, but they do seem to work, and they need something, like this laser, to bring them to the next level (like, for example, being useful). Here's a link: IBM's computer (one of many) [ibm.com]

Comment removed

[account_deleted]

Comment removed based on user account deletion