# Tag Info

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If you are looking for intuition about the subject, read Dirac's Principles of Quantum Mechanics. You need to read §2, §3 and the beginning of §10 until you see fit.

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The quantum evolution in open systems is non-unitary, and is effectively described, usually, by the Lindblad master equation. It provides a good description for e.g. modeling cavity loss in a system of atoms interacting with radiation (see this paper).

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First of all, it is indeed correct to model decoherence the system has to interact with what is called the "environment". Basically you have a joint CLOSED (unitary) evolution of system+environment, after which you discard the environment (technically called a partial trace), and you are left with the state of the system. Your "observer" can be taken as part ...

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If your electron is in a pure state then it's an eigenfunction, $\psi_e$, of the Hamiltonian describing it, $H_e$. The measuring system will also, in principle at least, be described by some wavefunction, $\psi_m$. If the two don't interact then the total wavefunction will just be a product: $$\Psi = \psi_e\psi_m$$ and the system won't change with time. ...

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When you measure the position of an electron that is in a pure energy state, what happens the energy becomes non-deterministic. An electron in a pure energy state is in a bound state. To "measure it" you have to excite it or , if it is in an already excited state measure the photon of its deexcitation. You cannot measure its position, while bound, to ...

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Some thoughts about Breuer (1995). Not really an answer, but too long to be a comment. Breuer concludes that ... (1) no theory can predict the future of the system where the observer is properly included. Breuer proves ... that (2) the observer cannot distinguish all phase space states of a system where he is contained. How can one conclude (1) ...

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If you're looking for a general solution to the schrodinger equation then yes, it is possible for the atom to be in a superposition of energy states. This does not violate conservation of energy. Can you see why? It is a subtle point. To start you off -- how do you measure the position of the electron in the first place? You must hit it with something. This ...

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I find your question a little unclear, but the following is my best understanding of your position. According to the MWI an observer will exist in multiple versions after a measurement. So then it is equally possible for him to be in either state and he should assign equal probability to each: let's call this the equality rule. It is important to note first ...

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Can one intuit (or calculate!) what this rate is from the electromagnetic field? Sure. For a given problem you'll have a system you care about $S$, and an environment $E$, which in this case is the electromagnetic field. The Hamiltonian for the system is something like $$H = H_S + H_E + H_I$$ where $H_S$ is the Hamiltonian for the system $S$, $H_E$ is ...

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