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  • This “oscillation” is called quantum superposition. In practice, the qbit doesn't oscillate but really has both values at the same time. We call this the quantum state of the qbit.

    This is a rather strong metaphysical claim that seems somewhat out of place in an introductory article. It would be like if I'm presenting GR and I say "but spacetime really is like a physical fabric that is actually physically bending and stretching." You will find many people in the literature, including Einstein himself, who disagree with this notion and would insist that you shouldn't reify the geometry in spacetime in GR as if it's a literal physical fabric but is instead a geometric tool used to predict the dispositions of particles. QM has even far more camps on how to properly conceive of the mathematical implications of the mathematics and it's probably best to not take such a strong stance in an article that is just introducing it, especially since you're not making it explicitly clear that is just your opinion and so it might mislead people to think that there is some academic consensus that the qubit "really has both values at the same time," which there is simply not.

    You must bombard it with photos. And at quantum scale, a single photon is really huge.

    Should this be "bombard with photons"?

    If a particle doesn't interact at all with its environment, it just doesn't exist by definition.

    This is again a metaphysical position, and it's a bit strange because this is one of the metaphysical postulates of relational quantum mechanics--that all that exists are interactions so if you speak of something independent of interactions then that thing doesn't actually meaningfully exist--yet relational quantum mechanics has an epistemic view on quantum states and not an ontological view that the particle is in "two states at once." The contradiction here is clear: you say the particle, when you aren't interacting/measuring it, is "really has both values at the same time," but then you also say if it doesn't interact, "it just doesn't exist." Which is it? You have to pick one. There are views that say it "really has both values at the same time," and in those views it does indeed exist, it exists in a physical superposition of states. There are views that say it does not exist: the particle only exists when it interacts with something, which in those cases it only ever has a single state in relation to what it is interacting with. There are also views that it just has one value and we don't know what it is.

    The particle is in a superposition state, which can be described as "50% 0, 50% 1". But when we measure it, we won't have something like 0.5. We have either 0 or 1. And the crazy thing is the qbit then keeps this value after the measure. Meaning several values in a row will all give the same value.

    As an interesting side note (not really a critique), if it was just real probabilities, you could actually reproduce a similar effect in a classical model with oscillations.

    You can imagine a clock signal that is oscillating really fast, if you measured the p-bit that is oscillating in this way, you would get an unpredictable value, and you could in fact alter the probability distribution you'd get just by changing the duty cycle of the p-bit. You can then also imagine that your measuring device also has a clock signal and only actually can measure the p-bit at each active high on the clock signal. If the clocks are out even slightly out of sync, and the oscillation was fast enough, you would measure a random probability distribution equivalent to duty cycle of the clock signal of the p-bit you're trying to measure, but if you perfectly synchronize the clocks, then you would constantly measure the p-bit at the same position in its cycle, and thus always measure the same value. Thus, you could have something that is oscillating appear to stop oscillating relative to a particular measuring device after it interacts with it, although for a third measuring device that is out of sync with the other two systems, those would both be oscillated but correlated relative to it.

    This can't easily be extended to explain quantum mechanics because particles aren't described by vectors of real probabilities like [0.5, 0.5] but by probability amplitudes, and the fact that the vector of probability amplitudes then sticks to a single value makes the thing a lot more complicated. Qubits also have three observables which adjusting the probabilities on one inherently affects the other. So each observable would need some sort of internal structure which itself is not oscillating but determines the duty cycle of the observables. You can imagine, for example, that the Bloch sphere is the internal structure, that it as if the observable has a spherical dial which adjusting it changes how the X, Y, and Z observables oscillate. Or, in the Two-State Vector Formalism, it would have two dials. This still wouldn't be sufficient because you would run into contradictions with Bell's theorem unless you also included some sort of superdeterministic or time-symmetric property, such as if the measuring device and qubit do not actually become synchronized when they interact but that the circuit always just so happens to evolve in such a way that they are already synchronized right before interacting.

    It might indeed be possible to formulate in terms of oscillations. There is already a formulation of quantum computing in the literature that is in terms of classical pendulums with nonlocal connections between them.

    • Wow, thanks for feedback. I've rephrased some of the sentences.

      You remarks make me think a talk I had we a colleague. I thought for a very long time that univers were actually like what we describ through equation. There were really some "energy gauge", "mass", "speed", etc... until this colleague told me "That's just a model, it's not the reallity. it gives good results in its field of application, but it will always be just an approximation."