ray3400 said:
I hate calculus, I'm guessing "quantum math" uses quadruple integrals embedded in an infinite series with 16 dimensions. I'm more interested in understanding how it works conceptually. I'm an software engineer so I was curious as to how the
Rules of Quantum Mechanics can be taken advantage of to build a new type of device. I am aware of quantum computers, I was wondering if entanglement could be somehow manipulated to communicate data.
I'm guessing from this thread that it is impossible and people have already tried different ways of making it work. I heard that it can't work because the data is random, but that's not the reason it can't work, random data can still be used as an event trigger. The reason it can't work is because it fundamentally relies on the receiving end knowing when the coupled quantum property goes from undetermined to determined, which apparently is impossible.
Here's a crude analogy of entanglement using nature as a computer system.
You have two particles, represented by messages. They get sent to two end-users. The messages are "sealed", so you have to invoke a process called "measurement" to see what's inside. The rule (that the system maintains) is that the messages are always the opposite of each other. Let's say "Yes" and "No".
Now, there are at least two ways that system could work. First, the system could simply randomly put "Yes" inside one message and "No" inside another. In QM terms this would be a "local hidden variable". The messages are predefined at the outset and, clearly, there is no way for one end user to send information to another end user simply by opening his message and seeing "Yes" or "No".
The other way is that the system could wait until someone opens a message and then decide. In a computer system this would involve communication, not between the end users, but between the end users computers and the central system. Also, in this case there is no way for one end user to communicate with another. It doesn't matter that the underlying system does some processing in "real time". The end users have no more control over the random choice of "Yes" or "No" that they get than in the previous example.
That's why you cannot communicate with someone using entanglement. You simply have absolutely no control over the data that the other user receives as a result of their measurement. Their measurements follow the same statistical pattern, regardless of what you do. Your measurements have no statistical influence on their measuerments.
In the above simple case, no matter what either user does, both users will get a simple, random sequence of equally likely "Yes" and "No" messages. If they get together afterwards, they will note that each sequence was a mirror of the other. But, there was never any way for one to influence what the other received. User A was never in a position to say: I want user B to get a "No" as the next message.
Note also that more sophisticated experiments (following Bell's theorem) have shown that in fact the simple model of local hidden variables cannot be what's happening. QM is more like the second example where the content of each message (somehow) is not decided until it is measured.
Now, re entanglement, this of course begs the question of how nature maintains this "real time" correlation of data? The answer is that no one knows and the question itself may not even be meaningful.
There was a thread on here a little while back about all the theoretical possibilities for how nature might maintain quantum entanglement. PS I've found it now - see below.
There's also a lecture here from the Royal Institution with a better analogy than mine, which might be worth watching:
