Recent content by Andeplane

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    Grover's Algorithm: is it really a search algorithm

    I was trying to construct an emulation of the grover algorithm in MATLAB myself which you can find here: http://folk.uio.no/anderhaf/grover.m [Broken] The whole point is that you have a problem where you have a total of 2^n possible states, and 0 < k < (2^n)/2 states are solutions to a...
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    Transfering Electricity w/o Medium? (Electron Beams?)

    I would guess that if the electrons were completely free to move (i. e. not in a conductor), they would repel each other so it would not be a concentrated beam after a short amount of time. But you could use some sort of electromagnetic radiation (microwaves maybe) to transfer the energy, and...
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    What is the connection between oracles and quantum physics?

    I would guess that if such an oracle ever existed, it would be fully explained by the density matrix as anything else. I do, however, believe that most physicists don't believe in such phenomena as oracles as the ones you describe.
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    How do complex numbers manifest themselves in the subatomic world?

    They play a huge role in quantum mechanics. They also are fundamental for describing waves in general. Elementary particles cannot be described without complex numbers (or something like geometric algebra where the behavior of the complex numbers are described using geometrical structures).
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    Natural linewidth of laser

    A laser works by exciting electrons in a very specific manner such that when the electron falls back into its ground state, it will send out a photon with a specified wavelength. But as one can show (done in...
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    Measurement disturbance - double slit

    venton; yes, there is a conceptual problem, because it's not just to cut the wire and then the information is destroyed. It's not that since WE as human beings cannot tell (remember, we cut the wire), the interference pattern comes back to life. But if we made this device that was completely...
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    Measurement disturbance - double slit

    Allright, say that you have the classical quantum mechanical example, a particle with spin up or down (for example an electron). Then it is possible to prepare the system (i have no idea how you do this in practice, but scientists are awesome) so that there is a 50/50 chance to measure spin up...
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    Measurement disturbance - double slit

    If we measure the position (i.e. what slit the electron passed through), the position gets sharply determined (and due to the uncertainty principle, the momentum is quite spread out). But now we know what slit the electron went through, so there isn't any superposition of the two slits anymore...
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    Are probabilities for Eigen Vectors of Hamiltonians unaffected as time evolves?

    The definition of the hamiltonian in QM is the operator that "controls" the time evolution. Usually the hamiltonian represents the energy, but sometimes this is not the case. An example of this is a time-dependent rotating magnetic field (which gives a time-dependent hamiltonian) where you can...
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    Are probabilities for Eigen Vectors of Hamiltonians unaffected as time evolves?

    I have no idea what the confusion are right now, but i'll try :p Say you have a system (potential and boundary conditions etc) so that the SE (Schrödinger Equation) is separable into a time-dependent part and a spatial-dependent part. Then, if the hamiltonian is time-independent (as you were...
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    Are probabilities for Eigen Vectors of Hamiltonians unaffected as time evolves?

    An eigenvector of the hamiltonian is a state that satisfies the time-independent SL. And yeah, all you get from the time evolution operator is a phase that will cancel out in any expectation value calculation and probability density calculation. If you have a system where the solution...
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    Can the de broglie formula still hold in a medium with reduced speed of light?

    Hi, I was discussing a question with a Ph.D-student at my uni that neither him or the professor were able to answer. The situation is the following; Light enters a medium going from i.e. vacuum. We know that the energy of the photons in the vacuum is E = h\nu and we have the de broglie...
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