- Contemporary messages sorted: [ by date ] [ by thread ] [ by subject ] [ by author ] [ by messages with attachments ]

From: Hal Finney <hal.domain.name.hidden>

Date: Thu, 5 Sep 2002 19:32:49 -0700

Wei writes:

*> I just found a paper which shows that if apparent quantum randomness has
*

*> low algorithmic complexity (as Schmidhuber II predicts), then FTL
*

*> communications is possible.
*

*>
*

*> http://arxiv.org/abs/quant-ph/9806059
*

This was an interesting paper but unfortunately the key point seemed

to pass by without proof. On page 5, the proposal is to use entangled

particles to try to send a signal by measuring at one end in a sequence

of different bases which are chosen by an algorithmically incompressible

mechanism. The assumption is that this will result in an algorithmically

incompressible set of results at both ends, in contrast to the state

where stable measurements are done, which we assume for the purpose of

the paper produces algorithmically compressible results.

The author writes: "This process of scrambling with the random template T

guarantees that Bob's modified N-bit long string of quantum measurements

is almost surely p-incompressible..., and that Alice's corresponding

string (which is now different from Bob's) is also (almost surely)

p-incompressible"

It's not clear to me that this follows. Why couldn't Bob's measurement

results, when using a randomly chosen set of bases, still have a

compressible structure? And why couldn't Alice's?

Also, does this result depend on the choice of an unbalanced system

with alpha and beta different from 1/2? This short description of

the signalling process doesn't seem to refer explicitly to special

alpha/beta values.

If not, could the procedure be as simple as choosing to measure in

the X vs + bases, as is often done in quantum crypto protocols? If we

choose between X and + using an algorithmically incompressible method,

will that guarantee that the measured values are also incompressible?

Hal Finney

Received on Thu Sep 05 2002 - 19:34:56 PDT

Date: Thu, 5 Sep 2002 19:32:49 -0700

Wei writes:

This was an interesting paper but unfortunately the key point seemed

to pass by without proof. On page 5, the proposal is to use entangled

particles to try to send a signal by measuring at one end in a sequence

of different bases which are chosen by an algorithmically incompressible

mechanism. The assumption is that this will result in an algorithmically

incompressible set of results at both ends, in contrast to the state

where stable measurements are done, which we assume for the purpose of

the paper produces algorithmically compressible results.

The author writes: "This process of scrambling with the random template T

guarantees that Bob's modified N-bit long string of quantum measurements

is almost surely p-incompressible..., and that Alice's corresponding

string (which is now different from Bob's) is also (almost surely)

p-incompressible"

It's not clear to me that this follows. Why couldn't Bob's measurement

results, when using a randomly chosen set of bases, still have a

compressible structure? And why couldn't Alice's?

Also, does this result depend on the choice of an unbalanced system

with alpha and beta different from 1/2? This short description of

the signalling process doesn't seem to refer explicitly to special

alpha/beta values.

If not, could the procedure be as simple as choosing to measure in

the X vs + bases, as is often done in quantum crypto protocols? If we

choose between X and + using an algorithmically incompressible method,

will that guarantee that the measured values are also incompressible?

Hal Finney

Received on Thu Sep 05 2002 - 19:34:56 PDT

*
This archive was generated by hypermail 2.3.0
: Fri Feb 16 2018 - 13:20:07 PST
*