Hello! I am new here and I will try my best to clarify my questions and not violate the forum rules. Just for the record, I am not particularly good at understanding equation-saturated explanations because I am not an expert. However, I did a lot of searching and I still don't understand these questions(call me dumb or whatever). Often I see others asking the same questions but unanswered. Please don't just refer me to some jargon-filled sites :) ::What I think are true (please correct me if I am wrong):: -A qubit can exhibit only 1 or 0 upon measurement. -Any disturbance can cause decoherence, which in turn causes wave function collapse and forces a qubit to assume 1 or 0 depending on probability. -2 or more qubits can be entangled. When one in a pair is measured to have i.e. an up spin the other is known to have a down spin (in most cases) and that the outcome of one is "in some way co-related" to the other. ::What I am very confused with:: 1.1 In a Bloch Sphere, how can a quantum state be represented by a dot on the sphere (or inside) when the state might be the spin (which needs to be an axis/direction)? 2.1 A qubit can be in a superposition of 1 and 0. Does it mean a certain value in-between 1 and 0 or simultaneously both 1 and 0 ? 2.2 Why is it that because they can be in superposition, they are capable of parallel computation? All sources simply say that because qubits can be in superposition therefore they can simultaneously compute many things. Without explanation! :X I thought, even if you perform many operations to a qubit, the final measurement show only a single 1 or 0 answer? 3.1 If measuring a qubit forces it to collapse to 1 or 0, what is the point of being able to superpose in-between 1 and 0? The result is still classical? 3.2 If the first measurement can be random (when not aligned with the measuring axis), doesn't that mean a quantum computer can give random answers? 3.3 If "measurement" would force a qubit to collapse to 1 or 0, why wouldn't an "operation"? I mean, both has to introduce external forces and why is it that changing the state of a qubit without looking at it would not force it to collapse? (Or would it? Then doesn't that imply the operation on an entangled qubit would break the entanglement, thus the entanglement is useless in manipulation of qubits?) 3.4 Except for the ion trap method, could you please name one or two other methods of practically measuring the state of a qubit? 4.1 When one in an entangled pair is measured, does the entanglement cease to exist (since the collapse of one instantly collapses the other)? If they disentangle upon measurement, what is the point of measuring the entangled partner instead of just measuring the qubit you want to see directly? (Since both ways collapse them?) 4.2 When two qubits are entangled, does that mean doing operations on one of it affects the other instantaneously in "some co-related way"? Some say it's a misconception. 4.3 Could you name a couple practical methods of doing operations on a qubit? e.g. flip the spin of a photon through using some electromagnetic wave. I just need the names and I will find out by myself. 5.1. Is it true that the faintest environmental disturbance (e.g. a very weak earthquake near a quantum computer, may exert microscopic forces on the qubits) will cause decoherence thus making the results totally nonsense? (This make a quantum computer extremely fragile and prone to break down..?) I would be grateful if somebody even attempted to answer some of it :) These are bugging me so much. Please include where you learned the answers from (does not have to be official sources) so I have a rough idea of its credulity, thank you very much! P.S. This is not a homework. I am just confused.