What would you do if you had 50 q-bits?

Question

if it were possible to create 50 entangled bits could they be engineered to the point where they are modelled as 50 inputs with 50 outputs?

50 q-bits can store 2**50 words. each word is 50 bits long.

what is the procedure for storing 2**50 words?

I'm sure i need some peripheral signal here.

What are they?

Answer 1

Making a qubit is not all that difficult.  Making a qubit that A) lasts long and B) can be manipulated is much more difficult.  Ã¢Â€ÂœStorage” is a complicated thing for qubits, since they are prone to decoherence (related to point A).  To make a qubit that stores stuff for a long time, you need to have more qubits than just one, so that you can do error correction.  In a classical computer, an example of error correction would be having a bit and copying it so you have three copies of the bit.  That way, if one of the bits were to randomly flip, you could check all three bits, see that two of them are the same, and correct the third bit.  Since quantum bits are much harder maintain, you would need far more involved error correction schemes, which would require far more functional qubits per information qubit.  So if you wanted 50 qubits to last for one second, you would actually need thousands of qubits and constant error correction.  And every time an operation is applied to a qubit (which would happen every time an error correction protocol was performed), this introduces some error since quantum operations are not perfect.  So you need even more qubits to error correct the operations.  Therefore, to have 50 information quibits, you would actually need many many many times more auxiliary qubits.

When you store your 2^50 words in your 50 qubits, it is not like storing 2^50 words on a hard drive.  On a hard drive, you can go back and access each word individually.  In the 2^50 words stored in a qubit, you actually have a superposition of all 2^50 words, and accessing any one of the words would immediately erase all (2^50)-1 other words.  This superposition is only good for parallel processing tasks, not for storage and recall tasks.  And even then, it is only good for certain types of problems that require parallel processing, again due to the measurement issue erasing all the other entries as soon as you do a measurement.

The procedure for writing these 2^50 words is actually not that complicated.  You just make a superposition of 2^50 words.  Which can be done by making a superposition of the 2 states (0 and 1) for all bits individually.  They way you do that is apply your control pulse for half the time it takes you to flip a qubit (this is called a pi/2 pulse).  What that control pulse actually is depends on what your qubits are.  In NMR quantum computing, it is an oscillating magnetic field tuned to a specific frequency.  In ion or atom quantum computers, it is usually a laser tuned to a specific frequency.  In josephson junctions, it is some bias or some oscillating current.  None the less, making the superposition of 2^50 states is not the problem and is not interesting.  It is doing something with 2^50 states that is interesting and currently not possible.  The problem is once you have your state written on your qubits, you have to perform your calculation before your state decays away to useless noise.  And to keep it from decaying away, you need to do error correction.  But there are no quantum computing systems that can currently error correct on 50 qubits faster than those 50 qubits would decay.

Answer 2

what are they

Answer 3

Free energy baby.