quantum information discussion at last saturdays tacos

[Robert Stratton]

On Oct 13, 2005, at 00:54, hal wrote:

> A few of us (at one end of the table) talked about
> what quantum information is about.  I was at a lecture
> on this subject and was astonished at the new
> ways of thinking about communications subjects that
>  we take for granted such as compression,
> error correcting codes, Shannon's capacity limits
> and the like.

It's pretty wild. A year or so ago, I spent some time visiting the  
single photon detector folks at NIST. They had an optical quantum  
communications link running across about 2 miles pointed out the  
window of one of the labs. It took several other beams to align, but  
once it was set up, it passed bits.

I'm sure they will cut both ways, but there a number of inherent  
properties that come for free with this sort of link that would  
otherwise require boxes of hardware to provide, such as privacy and  
error correction.

Having looked briefly at the business side of the "quantum  
technology" world, I wouldn't run out and buy any _system_ that  
anyone is selling right now, be it for cryptography or  
communications. Components, such as single photon detectors, on the  
other hand, seem to be for real now.