What is the processor equivalent? What is the memory equivalent? I’ve read it comes up with an infinity of possible solutions to a problem. How do you select the correct answer?
quantum computer
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How does a quantum computer work?
What is the processor equivalent? What is the memory equivalent? I’ve read it comes up with an infinity of possible solutions to a problem. How do you select the correct answer?
quantum computer
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it works by using all 9 available digits 1-9, a binary (normal) computer uses only 1’s and 0’s, to make a binary computer equal to a quantom computer, it would have to be bigger then a 5-story building and be cooled with somthing colder than nitrogen.
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You are thinking about computers on too high a level. There is no processor equivalent, there is no hard drive equivalent. To see the difference between quantum and regular (or classical) computers, you have to go directly to the very simplest part of the computer: the bit. As you may know, classical computers operate by manipulating bits which can be either 0 or 1 (or off and on). All computations are built up from series of manipulations of these 0’s and 1’s. Now anything that manipulates 0’s and 1’s can be considered a computer. In the computer you are currently working on, those 0’s and 1’s are made up of current pulses inside the processor and they are manipulated by transistors. But that is not the only classical computer. Really anything that can display two states, and if those states can be changed, can be called a classical computer. If you have red M&M’s (and you call them 0) and you have blue M&M’s (and you call them 1), and you have a trained monkey that does some specific operations (eats the red one when it gets a red one and a blue one), you can make a computer out of that. It will be a bad computer. But it will be a computer. My point is that what makes a computer a computer is the types of informatic operations it can do, not the system it is built on. The only reason we use currents and transistors is because it is much faster than other systems.
Now, let me get to the difference between a classical computer and a quantum computer. Remember that a classical computer has bits that can be 0 or 1. A quantum computer has what are called quantum bits or ‘qubits’ and these qubits can be 0 or 1 as well. But the difference is that qubits can also be 0 AND 1 AT THE SAME TIME. This is what is known as a “superposition” of 0 and 1, and the notion of superposition is incredibly fundamental to quantum mechanics, but is not something that we see in our macroscopic world. And all the power in quantum computing comes from this ability to be 0 and 1 at the same time. To see why this is useful, let me give you this example. Hopefully you know that numbers can be written in binary as a string of 0’s and 1’s (0=00, 1=01, 2=10, 3=11, etc). Now imagine I gave you the number 1 and I wanted you to add 1 to it using a classical computer. That would take you one computation to do that. And now, let’s say I did the same with a quantum computer. Again, it would take one computation. So quantum computers are no better at this point. But, now lets say I wanted you to add one to every number between 0 and 3 on your classical computer. Now, you would have to do 4 computations, you would add 1 to 0, then you would add 1 to 1, and so on, until you got to 3. However, for me on my quantum computer, I can use the idea of superposition to put two qubits in the state 00 AND 01 AND 10 AND 11 (that is 0 AND 1 AND 2 AND 3 in non-binary). Now I can add 1 to that state and I will get an output of a superposition of all the answers. So I needed to only do ONE computation while you needed to do 4. Now imagine I wanted you to add 1 to every number between 0 and a billion. You would have to 1 billion computations, I would still only have to do 1. So, hopefully I have shown you that quantum computers have a massive multiparallelism. Of course, quantum computers are not all cherries and sunshine. As it turns out, making that superposition can be tricky, and, more fundamental, there is a measurement problem. I can get all 1 billion answers after one computation, but I can only read out 1 of those answers, and to make matters worse, I can’t pick which answer I read out. In fact, I can’t even know what answer I got! So, all of the sudden, that makes my quantum computer basically useless for this problem (what’s the value of doing a computation if you can’t know the answer?). However, there are SOME questions where this measurement problem is not a problem. The main two problems are unstructured search (database searching) and factoring (factoring is critical to breaking cryptographic codes). But for almost ALL other problems, classical computers are as good as quantum computers, so will probably never be replaced by quantum computers. The only real value of a quantum computer, at this point, if you are not a physicist, is to break in and read secret documents or steal credit card numbers.
You asked how you select the correct answer out of the all the possible answers. The answer to that is you don’t. You can’t. There is absolutely no way to pick the right answer. The trick is asking a question where it doesn’t matter what answer you, or, in other words, EVERY answer is the correct answer. That is exactly why quantum computers are good at factoring and database searching. In factoring, any factor will work (if you have one factor, then the other factors become much easier to find) and in database searching, any correct answer is a correct answer, so works. This is the problem with quantum