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  1. M

    Why don't virtual particles cause decoherence?

    Thanks, but if virtual particles don't 'exist' or they are not necessary in many quantum theories, why do they exist? Please understand that I do not understand the large majority of scientific jargon on this thread, would it be possible for you to try to explain this as if to someone that is...
  2. M

    Why are only some photons virtual?

    Sorry it was hard to think of a good title. Essentially, why do only virtual photons carry the electromagnetic force? What stops 'normal' photons from carrying the EM force? Is it the fact that we can detect them? What decides whether a photon will be virtual and hence carry the EM force, or...
  3. M

    Why don't virtual particles cause decoherence?

    I was recently told virtual particles don't cause decoherence. Why not? Do they just never interact with their environment (apart from transferring energy/force) so they can never collapse a wavefunction?
  4. M

    Infinite Salesmen problem?

    If it is coding - then surely different coding may be used in different situations, creating an event where one research group codes the state 010 as the binary digits representing 7 whilst another group codes the same state but represents it as a 4. Since coding is arbitrary, how can we know...
  5. M

    Infinite Salesmen problem?

    Sorry for my late reply, I've been very busy recently. So since a probability amplitude is a collection of quantum states, then surely the probability amplitude denoting the state (101) is the same as the one denoting (110) since both states have two electrons with spin up and one electron...
  6. M

    Why do things 'decohere'?

    Please could you provide a link or explain how decoherence explains we will never see a superposition? Thanks, will look this up Thank you for that fantastic explanation. As to your last paragraph, I'm a bit confused between the difference between your interpretation and the standard...
  7. M

    Infinite Salesmen problem?

    I am very sorry. Please could you explain how a quantum register converts whatever there is to convert into a binary number? Disregard amplitudes, how do you get from a series of particles to a binary number? Do you literally have to measure every single one and see whether it has spin up or...
  8. M

    Infinite Salesmen problem?

    I'm sorry, I don't understand. In a classical system you have two possible results i.e. as you said it may be (+) volts for 1, and (-) volts for 0. However these are the final results. For qubits, although yes there are 1s and 0s, the answers are the amplitudes, which are 2^n many, rather...
  9. M

    Why do things 'decohere'?

    One more question, How can we 'create' superposition. Surely this is an oxymoron? Superposition is caused by a lack of interference with particles, so how, by interfering with particles, can we force them into superposition?
  10. M

    Why do things 'decohere'?

    Thank you, so what would you say was the most interpretation? Or is it all just speculation, with there being no 'true' explanation.
  11. M

    Why do things 'decohere'?

    Could someone please explain why superpositions collapse when we observe particles? Surely if it is because we have interacted with the particle, then any interaction would decohere a particle, i.e. why would the magnetic fields in two electrodes (which are containing a particle) not collapsing...
  12. M

    Infinite Salesmen problem?

    Sorry could you explain this? I believed that you get results through interference, i.e. constructive interference will heighten the probability of a certain amplitude being found. I thought that 'amplitude' denotes on of the possible states of the entire qubit system, and is a complex...
  13. M

    Infinite Salesmen problem?

    Thank you. So how would one convert these amplitudes, which are complex numbers, into integers (such as the test that found that 3*5=15 with a high probability)
  14. M

    Infinite Salesmen problem?

    I understand how superposition is used now however I've stumbled on a new thing which I am confused about (and which lectures don't seem to address). If you are using an algorithm to send waves such that you create constructive and destructive amplitudes among the qubits to get a high chance...
  15. M

    Infinite Salesmen problem?

    One of the main aims is to be able to solve the RSA-security which is the predominant encryption on the internet. It multiplies two prime numbers to get a 300 digit number. A supercomputer would take years-decades to solve this kind of thing since computer power expands exponentially, but since...
  16. M

    Infinite Salesmen problem?

    Apparently, that was the original purpose, then they realised that computational power of qubits expanded exponentially rather than polynomially, hence they are trying to apply it to other areas. Edit: Just watched another lecture, this time by Michael Nielsen. Simulating quantum systems is...
  17. M

    Infinite Salesmen problem?

    Thank you. I've just read your post so I will get on it today. In the meantime I read an article in the Scientific American which states: "Put another way, we can store 10^ 300 numbers on our 1,000 particles simultaneously. Then, by performing various operations on the particles and on some...
  18. M

    Infinite Salesmen problem?

    Thank you for your replies. I just watched a lecture by Scott Aaranson on NP/P etc problems so I think I've grasped the limitations of quantum computers and I'm beyond thinking they are a solution to any feasible problem. He talked about quantum computers using amplitudes of particles (and...
  19. M

    Infinite Salesmen problem?

    Please could you elaborate on how this superposition works then, in terms of what possible calculations it allows for? For example for one qubit do you now gain three possible states (Spin up/down/superposed)? I'm struggling to understand how the salesman problem is solved at all. All I've...
  20. M

    Infinite Salesmen problem?

    Hi, I'm looking into quantum computing, and if you could forgive my naivety I was wondering whether the superposition of a qubit could produce a one-step solution to an infinite salesman problem? The salesman problem is where a computer has to calculate the most efficient route for a man to...
  21. M

    Algebra without a calculator

    I talked to my friend about this and he pointed out that you can factorise it into the brackets (4t-1)(t-8) Giving t=8,1/4 And since t=x^1/2, you need to square 8 and 1/4 rather than square routing it like I was doing. Sorry for wasting your time, this turned out to be a very...
  22. M

    Algebra without a calculator

    The roots would be 2(sqrt2) and 1/2 however that's not the right answer (the right answer being 64 and 1/16). That still doesn't answer how to do it without a calculator though. Got any insights?
  23. M

    Algebra without a calculator

    But then, how can 8 and 1/4 be the answers if in the ( )( ) equation they will have to multiply to give 8? Surely it must be 8 and 1?
  24. M

    Algebra without a calculator

    Sorry for not showing my work, I just did so much and failed I thought it would be useless. Nonetheless I tried 4t^2-33t+8=0 and then factoring that but without using the quadratic formula to give me the answer of t=8, I didn't see how else I could do it (the quadratic formula requiring a...
  25. M

    Algebra without a calculator

    How would one solve the following WITHOUT a calculator? Sub in t as x^{\frac{1}{2}} 4x+8=33x^{\frac{1}{2}} I just don't see how to do this without a calculator. If I take t^2=x, then sub it in I need to do the quadratic formula which is too hard without a calculator/would take too...
  26. M

    Superposition and Pauli's principle

    Thank you, that clears everything up.
  27. M

    Is spin actually spin?

    I never did quite understood why they called them 'charm' and 'strange' quarks, it seems a bit too wishy-washy for physics especially such new discoveries. Wikipedia cites it's etymology as "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it...
  28. M

    Superposition and Pauli's principle

    Thank you for this clarification. I'm sorry but I still don't understand what you mean by the 'preparation of states', would you please be able to explain this in more layman's term? I understand that you are already stretching yourself by explaining it without mathematics, so I understand if...
  29. M

    Superposition and Pauli's principle

    Thank you, as much as I appreciate the time Tom took to write that I didn't understand any of it apart from a few words. I hope that some time in the future I can return to this thread and comprehend what he has written. Thank you for this succinct summary.
  30. M

    Superposition and Pauli's principle

    Does Pauli's exclusion principle apply to superposition or only collapsed states? I.e. could a particle be 'superposed' - if that is the word in the same state as another electron in a localized region? Also doesn't Pauli's exclusion principle create a form of measurement because...
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