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Difference and benefits of qubits compared to regular bits?

  1. Nov 4, 2011 #1
    Hello Forum,

    is someone able to explain, conceptually, in layman terms, the difference and benefits of qubits compared to regular bits?

  2. jcsd
  3. Nov 4, 2011 #2
    Re: Qubit!

    If I understand right:

    They are using statistics to know the state of a 2 bits after only measuring a single bit. The computations are more efficient this way.

    By using more fundamental mediums than coils (ram) or plates (hdd) to store information they can derive statistical methods for knowing with certainty the state of one bit after measuring another bit if the entire system is prepared in such a way. It is known as entanglement and the statistics are a bit complicated.

    A medium they might use is the direction of polarization of a photon. It can be either horizontal or vertical with some probability. They can prepare a state in which they know that 2 photons are always either horizontal or vertical simultaneously and by measuring one they know the state of the other.
  4. Nov 4, 2011 #3
    Re: Qubit!

    A bit is just a zero or one. True of false. On or off. Only two possible values.

    But a qubit is a quantum superposition of on or off. It's not quite like 55% off 45% on, but it's a little like that (you could arrange for those to be the probabilities when you measure when it's on or off, but you shouldn't think of it like classical probability). You shouldn't think of it as being halfway on or off, though, because when you measure to see whether it's on or off, it will either be on or off, nothing in between. However, before you measure, you can work with those infinitely many values. So, there is more information there. It's a little like the idea of analog computing, except it's using quantum effects to make it a little more digital when measurement comes into play.
  5. Nov 5, 2011 #4
    Re: Qubit!

    A bit can be either 0 or 1. A qubit can be a quantum superposition of |0> an |1>. The benefit of the latter is that as a qubit progresses through a computation the final answer will exhibit interference effects from the different routes it could take. Algorithms can be designed so that interference causes maximums around the desired answer. Using this method algorithms can be created that for some problems work much faster.
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