Where it's at in Quantum Gravity (TWF 235)

[Martin]

John Baez just came out with a new edition of This Week's Finds in Mathematical Physics

 

http://math.ucr.edu/home/baez/week235.html

 

If you want to print it out, it is 8 pages on my printer and the first 4 and half pages are about QUANTUM COMPUTING (where they are actually making computerlike things happen in a lab in Canada, which he visited, and they involve quantum effects rather than classical----it sound pretty far out) and

then the last 3 or 4 pages of printout are about some of the latest work in QUANTUM GRAVITY

 

I think Baez is one of the most creative people in the business and I think he and his co-workers are hitting top form now. He's a good communicator too. It is still hard to understand. All you get is a taste of the flavor, the real ice cream is out of reach. but it still can be worth a read.

[5614]

What sounds far out about quantum computers?

 

I haven't read the 8 pages... is it the actual content of that report you don't like (think is "far out") or the whole idea of quantum computers.

 

Because quantum computers are real. They have working prototypes. They're still quite slow running, but they are working research prototypes.

[Martin]

What sounds far out about quantum computers?

 

I haven't read the 8 pages... is it the actual content of that report you don't like (think is "far out") or the whole idea of quantum computers.

 

Because quantum computers are real. They have working prototypes. They're still quite slow running' date=' but they are working research prototypes.[/quote']

 

do us a favor 5614, tell us about it. Give some links-----photographs of working prototypes if you like.

Probably the customary thing is to start a fresh thread, but at the moment I feel easy about going off topic here. want to do some educational posts about current state of quantum computer research? go for it.

 

to me it is "far out" because although I have been hearing about it it still sounds, well "far out". cant think of a better term.

 

did you ever visit Scott Aaronson's blog? he is at that place in Canada---waterloo, associated with Perimeter inst. entertaining blog. he studies quantum computing

http://www.scottaaronson.com/blog/

[Locrian]

A working prototype of a quantum computer? Not that I've heard of, and not unless your definition of "computer" is pretty lenient. I've never heard of anyone stringing together more than a few qubits at a time, and those only operate under pretty severe restrictions, including being electromagnetically and thermally sealed.

 

There are still people who think a large-scale quantum computer isn't even possible due to issues with decoherence.

 

Maybe you've heard something new we haven't 5614?

 

PS: And thanks for another good link Martin

[5614]

I'm guessing my definition of "computer" is quite lenient in this case.

 

In 1999 there was a QC that could count to 4:

http://web.mit.edu/newsoffice/1999/quantum-0714.html

 

http://www.trnmag.com/Stories/2004/040704/Sturdy_quantum_computing_demoed_040704.html

(look at the 4th para)... it's a prototype that can "execute a quantum search algorithm despite environment noise". This only has 4 qubits, so whether one could classify it as a computer is questionable. But then again that is why I said: "They're still quite slow running, but they are working research prototypes" meaning they might be useless at the moment, but they're being developed and worked on. These are the raw foundations.

 

And I do agree with you two, some people say they are not possible or are far too complex to ever become more powerful than their electrical counterparts.

 

This:

http://www.trnmag.com/Stories/052301/Light_computer_runs_quantum_algorithm_052301.html

team of researchers questioned whether it would be possible to build a QC and so developed a "Q"C which worked on light or electromagnetic radiation.

 

Researchers at IBM proved (using a QC) that 5*3=15

http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2001/12/20/MN46203.DTL

 

In 2005

"A scalable quantum computer chip for atomic qubits was built for the first time by researchers at the University of Michigan, offering hopes for making a practical quantum computer using conventional semiconductor manufacturing technology"

-- http://en.wikipedia.org/wiki/Timeline_of_quantum_computing#2005 (can't find any other link to it, it's the bottom bullet point of 2005)

 

A 12 qubit QC has been made "Despite decoherence, the researchers reached a 12-coherence state and decoded it using liquid state nuclear magnetic resonance quantum information processors":

http://www.sciencedaily.com/releases/2006/05/060508164700.htm

the abstract is here:

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000096000017170501000001&idtype=cvips&gifs=Yes

 

And as I posted last week in the News forum a new 2D ion trap, which is an important breakthrough for the QC experimentalists, has been developed:

http://www.newscientisttech.com/article/dn9502-flat-ion-trap-holds-quantum-computing-promise.html

 

A working prototype of a quantum computer? Not that I've heard of, and not unless your definition of "computer" is pretty lenient. I've never heard of anyone stringing together more than a few qubits at a time, and those only operate under pretty severe restrictions, including being electromagnetically and thermally sealed.

So I suppose that is right, although with the most recent 12 qubit it is getting slightly bigger. I'm not sure about the "severe restrictions" regarding the latest prototypes.