All-optical networking Was: [Re: Notes on the Internet for Bell Heads]

Sat Jul 13 00:36:41 UTC 2002

The discussion is certainly entertaining, but -- 

1) All-optical networking is a bunch of nonsense until optical processing 
   ability includes complete set of logic and storage elements - i.e. 
   achieving fully blown optical computing.

   Rationale for the statement: telecom is fundamentally a multiplexing 
   game, and w/o stochastical multiplexing a network won't be able to 
   achieve price/performance comparable to that of stochastically muxed 
   network.  Stochastical multiplexing requires logic and storage.

   The current opcial gates are all electrically-controlled, and either 
   mechanical (and wear rather  quickly, too, so you can't switch them 
   per-packet or whatever), or iherently slow (liquid crystals), or 
   potentially fast (poled LiNbO3 structures, for example) but requiring 
   tens of kV per mm, making it slow to charge/discharge. 

   Besides, your truly years ago invented a practical way to achieve 
   nearly infinite switching capacity in electronics.  Too bad, Pluris didn't
   survive the WorldCom scandal, as some investors suddenly got cold feet.

2) Wiretapping does not require storage of the entire traffic stream; and 
   filtering for the target sessions can be done relatively easily at wire 
   speed.

3) Nitpicking:

> I think you may be thinking about quantum-entangled pairs. That
> phenomena is better suited to cryptography than general networking.
> 
> In an entangled system, both recipients would know pretty quickly that they
> did not receive their photons as there would be an early 'measurement' on
> one end, and a missing photon on the other.

   You cannot detect "measurement" per se.  What you get is skewed 
   statistics;  the entangled pairs obey Bell inequalities, which no
   classical system can.  This gives an opportunity to detect insertion of 
   anyting destroying entanglement of the pair - but only statistically.  
   You need to send enough pairs to distinguish normal noise from intrusion 
   reliably.

   Besides, quantum entanglement cannot be used to send any information at 
   all.  What it gives is the ability to get co-ordinated sets of 
   measurements at the ends, but the actual results of those measurements 
   are random.  I.e. you can generate identical vectors of random bits at the 
   ends, but cannot send any useful message across using only 
   entanglement.

   Therefore quantum entanglement (aka Einstein-Podolsky-Rosen paradox) 
   does not violate the central postulate of the special relativity theory (that 
   no kind of entity can propagate faster than the speed of light in 
   vacuum, in any non-accelerating reference frame).

--vadim