Classical to Quantum!

Hi,

Word  "Quantum" is going global from the den of physics.

"Quantum" cryptograhy - seems to be toughest,deepest and nearly
unbreakable
"Quantum" information theory - seems to explore new dimension of
information e.g  entropy is so important term in
themodynamics,astrophysics,information theory,coding theory
"Quantum" signal processing - new branch of DSP brings new dimension
in signal analysis
"Quantum" communication - Teleportation? what else ?

It seems rich mathematics of quantum mechanics is stemed into above
areas - not exactly the abstract concept of quantum mechanics(debate?)

I would like to know how classical reseachers,professors are keen to
spearhead
quantum globalization - well feasibility of practical quantum devices
is a question - but how long?

Santosh

On 2004-08-10 11:59:01 +0200, santosh.nath@ntlworld.com (santosh nath) said:

> Hi,
> 
> Word  "Quantum" is going global from the den of physics.
> 
> "Quantum" cryptograhy - seems to be toughest,deepest and nearly
> unbreakable
> "Quantum" information theory - seems to explore new dimension of
> information e.g  entropy is so important term in
> themodynamics,astrophysics,information theory,coding theory
> "Quantum" signal processing - new branch of DSP brings new dimension
> in signal analysis
> "Quantum" communication - Teleportation? what else ?
> 

I'd say this is mostly a "marketing" buzzword kinda thing.

Usually these terms are invented to imply that a new era in <enter your 
favorite discipline here> is about to begin. Most of these buzzwords 
start from people who earn their money through commercial research, by 
granting licenses on patent rights etc.

If the buzzword is a good one and gets widely promoted, it will 
eventually "leak" into the educational area as well (to help selling 
books).

The reason that this phenomenon exists is primarily to impress 
investors who are rarely qualified to judge about the validity of these 
claims (and, to a lesser degree, customers or readers of papers and 
books).

It should be noted that true new eras usually come and go silently. A 
new buzzword has rarely (but still sometimes) something to do with a 
truly new era.
-- 
Stephan M. Bernsee
http://www.dspdimension.com

santosh nath wrote:
> Hi,
> 
> Word  "Quantum" is going global from the den of physics.
> 
> "Quantum" cryptograhy - seems to be toughest,deepest and nearly
> unbreakable

Quantum cryptography is used to distribute private keys for classical 
cryptography over quantum communication channels. If the laws of quantum 
mechanics hold, quantum cryptographic key exchange protocols can be 
provably secure. This is not a buzz word but already existing 
technology, see for example: 
http://www.geneva.ch/_geneva_idquantique_cryptography.htm


> "Quantum" information theory - seems to explore new dimension of
> information e.g  entropy is so important term in
> themodynamics,astrophysics,information theory,coding theory

In a way, quantum coding theory is a (literally) natural extension to 
classical coding theory. You can think of the linear block code matrices 
(these matrices just contain 0 and 1 entries) as linear maps on a 
hilbert space, where they operate on quantum states.

> "Quantum" signal processing - new branch of DSP brings new dimension
> in signal analysis

Never heard of this.

> "Quantum" communication - Teleportation? what else ?

Transmiting quantum states over a quantum communication channel. This is 
  relied on in, for example, quantum cryptography. Quantum teleportation 
and superdense coding are other applications.


> It seems rich mathematics of quantum mechanics is stemed into above
> areas - not exactly the abstract concept of quantum mechanics(debate?)

Well, if you are talking about quantum information processing, the 
mathematics is quite simple (as compared to infinte dimensional quantum 
systems). It involves some basic linear algebra: you are always looking 
at unit-length vectors in a 2^n dimensional hilbert space, where n is 
the number of quantum bits. These vectors can be manipulated by 
orthogonal transforms (for example the DFT). They can also be "measured" 
(which means they are projected onto some aribtrary o.n. basis set of 
vectors), but you can only reliably distinguish 2^n states (there are a 
lot more unit-length vectors than that in a 2^n dimensional hilbert space).

There are (expectedly) some weird corollaries from the axioms of quantum 
information. For example, it is not possible to copy a quantum state. 
Quantum computation always has to be reversible, in the thermodynamic 
sense. Making a copy is not reversible process.

The difficulty really lies in the applications: where do quantum 
information processing system outpreform classical information 
processing systems? That's the Puddels Kern, to quote recent discussion 
here, and so far there were some interesting results (an amazingly large 
amount due to one single person - http://www-math.mit.edu/~shor/), but I 
feel the real break point is still ahead.


> I would like to know how classical reseachers,professors are keen to
> spearhead
> quantum globalization - well feasibility of practical quantum devices
> is a question - but how long?

As you can see above, some quantum information systems are already up 
and running. A general "quantum computer" still seems to be far away in 
the future. We'll see as time develops :-).


> 
> Santosh

Regards,
Andor

Andor Bariska wrote:
> santosh nath wrote:
> 
>> Hi,
>>
>> Word  "Quantum" is going global from the den of physics.
>>
>> "Quantum" cryptograhy - seems to be toughest,deepest and nearly
>> unbreakable
> 
> 
> Quantum cryptography is used to distribute private keys for classical 
> cryptography over quantum communication channels. If the laws of quantum 
> mechanics hold, quantum cryptographic key exchange protocols can be 
> provably secure. This is not a buzz word but already existing 
> technology, see for example: 
> http://www.geneva.ch/_geneva_idquantique_cryptography.htm
> 
> 
>> "Quantum" information theory - seems to explore new dimension of
>> information e.g  entropy is so important term in
>> themodynamics,astrophysics,information theory,coding theory
> 
> 
> In a way, quantum coding theory is a (literally) natural extension to 
> classical coding theory. You can think of the linear block code matrices 
> (these matrices just contain 0 and 1 entries) as linear maps on a 
> hilbert space, where they operate on quantum states.
> 
>> "Quantum" signal processing - new branch of DSP brings new dimension
>> in signal analysis
> 
> 
> Never heard of this.

There was an article in IEEE Signal Processing magazine by Oppenheim and 
one of his students, whos name I should remember, a year or 2 back on 
this topic.


> 
>> "Quantum" communication - Teleportation? what else ?
> 
> 
> Transmiting quantum states over a quantum communication channel. This is 
>  relied on in, for example, quantum cryptography. Quantum teleportation 
> and superdense coding are other applications.
> 
> 
>> It seems rich mathematics of quantum mechanics is stemed into above
>> areas - not exactly the abstract concept of quantum mechanics(debate?)
> 
> 
> Well, if you are talking about quantum information processing, the 
> mathematics is quite simple (as compared to infinte dimensional quantum 
> systems). It involves some basic linear algebra: you are always looking 
> at unit-length vectors in a 2^n dimensional hilbert space, where n is 
> the number of quantum bits. These vectors can be manipulated by 
> orthogonal transforms (for example the DFT). They can also be "measured" 
> (which means they are projected onto some aribtrary o.n. basis set of 
> vectors), but you can only reliably distinguish 2^n states (there are a 
> lot more unit-length vectors than that in a 2^n dimensional hilbert space).
> 
> There are (expectedly) some weird corollaries from the axioms of quantum 
> information. For example, it is not possible to copy a quantum state. 
> Quantum computation always has to be reversible, in the thermodynamic 
> sense. Making a copy is not reversible process.
> 
> The difficulty really lies in the applications: where do quantum 
> information processing system outpreform classical information 
> processing systems? That's the Puddels Kern, to quote recent discussion 
> here, and so far there were some interesting results (an amazingly large 
> amount due to one single person - http://www-math.mit.edu/~shor/), but I 
> feel the real break point is still ahead.
> 
> 
>> I would like to know how classical reseachers,professors are keen to
>> spearhead
>> quantum globalization - well feasibility of practical quantum devices
>> is a question - but how long?
> 
> 
> As you can see above, some quantum information systems are already up 
> and running. A general "quantum computer" still seems to be far away in 
> the future. We'll see as time develops :-).
> 
> 
>>
>> Santosh
> 
> 
> Regards,
> Andor
> 

Stan: did you really need to quote the whole text for that one 
sentence? That's pretty uneconomic... ;-)
-- 
Stephan M. Bernsee
http://www.dspdimension.com

Stephan M. Bernsee <spam@dspdimension.com> writes:

> Stan: did you really need to quote the whole text for that one
> sentence? That's pretty uneconomic... ;-)

In an era where mult-megabyte binaries are distributed across
usenet, 3.7 kB of text is not really uneconomical, but it
is inconvenient for those reading!

(In case you missed it, I'm agreeing with the intent of your
comment.)
-- 
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124

Stephan M. Bernsee wrote:
> 
> Stan: did you really need to quote the whole text for that one sentence? 
> That's pretty uneconomic... ;-)

I was busy.

On 2004-08-10 18:32:35 +0200, Stan Pawlukiewicz <spam@spam.mitre.org> said:

> Stephan M. Bernsee wrote:
>> 
>> Stan: did you really need to quote the whole text for that one 
>> sentence? That's pretty uneconomic... ;-)
> 
> I was busy.

Yeah, me too - reading it! ;-)
-- 
Stephan M. Bernsee
http://www.dspdimension.com

Stephan M. Bernsee wrote:
> On 2004-08-10 11:59:01 +0200, santosh.nath@ntlworld.com (santosh nath) 
> said:
> 
>> Hi,
>>
>> Word  "Quantum" is going global from the den of physics.
>>
>> "Quantum" cryptograhy - seems to be toughest,deepest and nearly
>> unbreakable

There's no "nearly" about it.  QC uses the spin of photons to make a 
message that cannot be intercepted and retransmitted.  Anyone who reads 
the message destroys it in the process.

For more info, read The Code Book by Simon Singh.

[snip]

> 
> I'd say this is mostly a "marketing" buzzword kinda thing.


... but in the case of quantum cryptography, it is a description of the 
fundamental nature of the technique.

On 2004-08-10 20:24:25 +0200, Mark Borgerding <mark@borgerding.net> said:

> Stephan M. Bernsee wrote:
>> On 2004-08-10 11:59:01 +0200, santosh.nath@ntlworld.com (santosh nath) said:
>> 
>>> Hi,
>>> 
>>> Word  "Quantum" is going global from the den of physics.
>>> 
>>> "Quantum" cryptograhy - seems to be toughest,deepest and nearly
>>> unbreakable

I think you quoted me saying that - just for the record, I didn't.

> There's no "nearly" about it.  QC uses the spin of photons to make a 
> message that cannot be intercepted and retransmitted.  Anyone who reads 
> the message destroys it in the process.

I'm curious: how do you decode it then?

>> I'd say this is mostly a "marketing" buzzword kinda thing.
> 
> ... but in the case of quantum cryptography, it is a description of the 
> fundamental nature of the technique.

Point taken.
-- 
Stephan M. Bernsee
http://www.dspdimension.com