(This was first posted to a newsgroup but there were no replies;(adsbygoogle = window.adsbygoogle || []).push({});

so I am trying to post it here).

I understand quantum teleportation works on qubits, but i can also

work on regular bits. Suppose Alice has a message bit S. S is

repeatable, because it is a regular bit. Now Alice wants to send it to

Bob and she is willing to repeat the message 1,000,000 times.

So, she teleports it to Bob. Both Alice and Bob receive, from a

middleman Moe, a stream of entangled particles. In total Moe sends

1,000,000 bursts of entangled photons--each burst consists of at least

one entangled photon going left to Alice, and one going right to Bob.

Quantum Teleportation was designed to work on qubits, which in general

cannot be cloned. But, suppose we have a classical bit S we want to

send from Alice to Bob. Then we can try to send it 1,000,000 times.

For each attempt, there is an entangled particle distributed from Moe

to Alice and to Bob.

So Alice manipulates its entangled qubit with its message bit S, and

the resulting qubit is interrogated to produce two classical bits X

and Y. Normally, to "teleport" information from Alice to Bob, Bob

receives an entangled particle from Moe (the middleman) and then

detects the entangled qubit two different ways, depending on the

classical information X and Y that was sent.

My question is: what if we don't send any classical bits? There are 2

bits of classical information per burst (attempted message send). Thus

there is a 25% chance we will receive the message that was sent!

If we send the message 1,000,000 times, then won't the message be

received 250,000 times? That's pretty good.

My question is, what happens the other 750,000 times?

Basically, my setup (for review) is a simple quantum teleportation

setup, except instead of using the classical bits sent by Alic to Bob,

we generate two random numbers (bits) at Bob and use them instead!

My hope - unfounded at present - is that 750,000 times when the

classical bits guessed are wrong, we receive a random BIT on the

output. I might be wrong. Maybe instead we receive a random QUBIT.

But if we have "signal" 250,000 times and "noise" 750,000 times, and

half the noise is 0 and half the noise is 1, that means we receive

250,000 + 750,000 / 2 = 250,000 + 375,000 = 625,000 signals and

375,000 noise bits.

Thus. If I send a message from Alice to Bob 1,000,000 times, I expect

to receive the message over 60% of the time; there will be the wrong

message (opposite bit) under 40% of the time. Can't a computer easily

tell whether 0 occurred more frequently than 1 at Bob's receiving

station, or whether 1 occurred more frequently than 0?

But this cannot be right. If it were, strange things indeed would be

possible. Quantum teleportation was not designed to be used in this

way. But what if it worked? Then maybe, just maybe (I'm speculating

here), we can distribute entangled particles across time -- the future

can receive one entangled particle and the past, the other. This can

be done by slowing down light, or sending it through 10km of circular

fiber optics channel (John Cramer's idea).

Normally a classical channel is needed to send a message, but since

we're sending a classical bit we can send it 1,000,000 times and let

majority rule. Without needing a classical channel to send information

from the future to the past, we can rely on entanglement.

And that is where we get ourselves into trouble. For, what if it

worked? If classical bits can be sent from the future to the past,

what does it mean? My question is as follows. If I detect a random

qubit, maybe there are now two universes. Thus the past had one

universe, there are two futures. If the future sends a message to the

past, which future gets to talk?

Quantum computers have severe limitations. For example, if this

universe splitting were real, the output bit (computed using

reversable logic using quantum gates) exists in two universes. We can

CNOT them together, i.e. I can tell whether or not f(0) = f(1). That's

all fine, but I want to perform nonlinear operations -- rather than

xor'ing two bits output from a quantum circuit, I want to OR them

together (this will make it possible to solve exponential-time

problems in polynomial time, i.e. subset sum, encryption cracking, and

so on).

But if I could split this universe into two universes and then send

messages from the future to the past, what if I could receive two

messages through two separate channels? The past receives two messages

then! The idea is to OR them together and then send them to the past's

past. By repeating this process, I can find any f(X) where X is a

vector of unknown bits, and f is some boolean function that returns 1

if X is in the set and 0 if X is not in the set.

Before I try to figure out how to build an "exotic network" (i.e.

quantum computer that sends messages from the many futures to a single

past to exploit massive parallelism), I want to make sure my idea is

grounded in reality.

Anyone with a better understanding of quantum mechanics out there,

care to speculate about what the outcome of my proposed experiment

would be?

All we need to do is prepare a message to teleport that is exactly 0,

then teleport it from Alice to Bob with Bob not really using the

classical bits Alice is sending, but instead using random bits for the

two classical bits sent over the classical channel. We repeat the

experiment 1 million times. Then we change the message from being

exactly 0 to being exactly 1 and do the experiment another 1 million

times.

If anyone out there knows of any labs with access to quantum

teleporation equipment, what do you think ? It doesn't sound like it

would be expensive. Since the classical channel is essentially random,

I was wondering if maybe we could make it cheaper, by always using 0

for the classical bits.

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# Is Quantum Teleportation possible without a classical channel?

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