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binary-dataquantum-computing

Quantum computing vs traditional base10 systems


This may show my naiveté but it is my understanding that quantum computing's obstacle is stabilizing the qbits. I also understand that standard computers use binary (on/off); but it seems like it may be easier with today's tech to read electric states between 0 and 9. Binary was the answer because it was very hard to read the varying amounts of electricity, components degrade over time, and maybe maintaining a clean electrical "signal" was challenging.

But wouldn't it be easier to try to solve the problem of reading varying levels of electricity so we can go from 2 inputs to 10 and thereby increasing the smallest unit of storage and exponentially increasing the number of paths through the logic gates? I know I am missing quite a bit (sorry the puns were painful) so I would love to hear why or why not. Thank you


Solution

  • "Exponentially increasing the number of paths through the logic gates" is exactly the problem. More possible states for each n-ary digit means more transistors, larger gates and more complex CPUs. That's not to say no one is working on ternary and similar systems, but the reason binary is ubiquitous is its simplicity. For storage, more possible states also means we need more sensitive electronics for reading and writing, and a much higher error frequency during these operations. There's a lot of hype around using DNA (base-4) for storage, but this is more on account of the density and durability of the substrate.

    You're correct, though that your question is missing quite a bit - qubits are entirely different from classical information, whether we use bits or digits. Classical bits and trits respectively correspond to vectors like

    Binary:  |0> = [1,0];   |1> = [0,1];
    Ternary: |0> = [1,0,0]; |1> = [0,1,0];  |2> = [0,0,1];
    

    A qubit, on the other hand, can be a linear combination of classical states

    Qubit: |Ψ> = α |0> + β |1>
    

    where α and β are arbitrary complex numbers such that such that |α|2 + |β|2 = 1.

    This is called a superposition, meaning even a single qubit can be in one of an infinite number of states. Moreover, unless you prepared the qubit yourself or received some classical information about α and β, there is no way to determine the values of α and β. If you want to extract information from the qubit you must perform a measurement, which collapses the superposition and returns |0> with probability |α|2 and |1> with probability |β|2.

    We can extend the idea to qutrits (though, just like trits, these are even more difficult to effectively realize than qubits):

    Qutrit: |Ψ> = α |0> + β |1> + γ |2>
    

    These requirements mean that qubits are much more difficult to realize than classical bits of any base.