Quantum mechanics describes the microscopic properties of nature in a regime where classical mechanics no longer applies. It explains phenomena such as the wave-particle duality, quantization of energy and the uncertainty principle and is generally used in single body systems. Use the ...

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To calculate the correlation functions of an XX spin chain, Wick's theorem is used. But is it valid for a chain of any size?

The correlation functions found in Barouch and McCoy's paper (PRA 3, 2137 (1971)) for the XX spin chain use a method which uses Wick's theorem. For the zz correlation function, this gives $\langle ...
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Path integral vs. measure on infinite dimensional space

Coming from a mathematical background, I'm trying to get a handle on the path integral formulation of quantum mechanics. According to Feynman, if you want to figure out the probability amplitude for ...
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Jauch, Piron, Ludwig -> QFT? [duplicate]

Possible Duplicate: What is a complete book for quantum field theory? At the moment I am studying Piron: Foundations of Quantum Physics, Jauch: Foundations of Quantum Mechanics, and ...
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What does an atom radiate: a wave packet or a single photon?

What does an atom radiate: a wave packet or a single photon?
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Fermi's Golden Rule

It is well known that to calculate the probability of transition in the scattering processes, as a first approximation, we use the Fermi golden rule. This rule is obtained considering the initial ...
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Electron transitions in an infinite square well

Consider an electron in an infinite square well. The expectation values of momentum and angular momentum are all zero for energy eigenstates. An electron transition is accompanied by the emission or ...
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Total number of subatomic particles in the universe. Are they finite ? assuming any of GR or QM or even ST

Total number of subatomic particles in the universe. Are they finite ? assuming any of GR or QM or even ST.
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Separation of variables, eigenfunctions of the Dirac operator

Disclaimer: I am not a physicist; I am a geometer (and a student!) trying to learn some physics. Please be gentle. Thanks! When solving the Schrödinger equation for a particle in a spherical ...
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Is it possible to determine timescales of electron dynamics from the natural linewidth of an electronic transition?

A lot of work has been done recently on electron dynamics using attosecond pump-probe techniques; for instance in this paper. In this particular paper, the authors photoionized the neutral ...
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What is an analog to QM's Hilbert space in GR?

I've read that QM operates in a Hilbert space (where the state functions live). I don't know if its meaningful to ask such a question, what are the answers to an analogous questions on GR and ...
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Appearance of atoms

I was watching a documentary entitled "The Atom" and one of the statements made was that Atoms behave differently when we look at them. I wasn't too sure about the reasoning behind this and i'm hoping ...
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Teleportation by quantum isolation

This is a thought experiment, so please don't treat it too harsh :-) Short: If we could isolate two places A and B in the universe from all and any interaction with the surroundings, is there a ...
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Is there a difference between observing a particle and hitting it with another particle?

First, let me state that I'm a lot less experienced with physics than most people here. Quantum mechanics was as far as I got and that was about 9 years ago, with no use in the meantime. A lot of ...
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Madelung transformation

What is the Madelung transformation and how is it used?
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Why is it hopeless to view differential geometry as the limit of a discrete geometry?

This is a follow-up question to Introductions to discrete space-time: Why is this line of thought hopeless? Classical mechanics can be understood as the limit of relativistic mechanics $RM_c$ ...
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Is there a method for differentiating fractional quantum Hall states aside from finding Chern numbers?

The ground state for a quantum Hall system on a torus with fractional filling factor can be classified by the Chern number, which is why the Hall conductance is quantized. Is there another method or ...
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Correspondence principle

Is there a precise mathematical derivation for the correspondence principle for which I can replace $E \rightarrow i \hbar \frac{\partial}{\partial t}$ and $p \rightarrow -i \hbar \nabla$?
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768 views

Could teleportation ever really happen?

Could any form of matter teleportation every really happen? If so, what form would it take? Some science-fiction talks about literally sending the atoms from one location to another; others talk of ...
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Linearity of quantum mechanics and nonlinearity of macroscopic physics

We live in a world where almost all macroscopic physical phenomena are non-linear, while the description of microscopic phenomena is based on quantum mechanics which is linear by definition. What are ...
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Particle wavefunction and gravity

Suppose a particle has 50% probability of being at location $A$, and 50% probability being at location $B$ (see double slit experiment). According to QM the particle is at both $A$ and $B$ at the same ...
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photoelectric effect

A 1.0 mW laser ($\lambda$ = 590 nm) shines on a cesium photocathode (ϕ = 1.95 eV). Assume an efficiency of $10^{-5}$ for producing photoelectrons (that is, 1 photoelectron is produced for every 10^5 ...
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Is it guaranteed that wavefunction is well behaved everywhere?

I don't really know much about Quantum mechanics, but would like to know one simple fact. The state function $\Psi(r, t)|$ whose magnitude gives the probability density of the position of the ...
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532 views

Alkali atom - photon interaction in zero magnetic field

An alkali atom has a single outer electron that interacts with incoming photons of the right wavelength (for alkalies it's in the visible & IR range). If there is an external magnetic field, the ...
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1answer
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Explanation of the experiment with Mach–Zehnder interferometer (self-interference of a single photon)

Here is the description of experiment which uses Mach–Zehnder interferometer http://en.wikipedia.org/wiki/Mach-Zehnder or http://departments.colgate.edu/physics/research/Photon/root/ajpbs02.pdf ...
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What does a Field Theory mean?

What exactly is a field theory? How do we classify theories as field theories and non field theories? EDIT: After reading the answers I am under the impression that almost every theory is a ...
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161 views

Is there a simple way to express the 2ⁿ+1 mutually unbiased bases for n qubits?

The title says it. An explanation for only 2 qubits would already be interesting, since I already have difficulties to find the 5 MUBs in this simple case.
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Is Angular Momentum truly fundamental?

This may seem like a slightly trite question, but it is one that has long intrigued me. Since I formally learned classical (Newtonian) mechanics, it has often struck me that angular momentum (and ...
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What categorical mathematical structure(s) best describe the space of “localized events” in “relational quantum mechanics”?

In a recent (and to me, very enlightening) paper, entitled "Relational EPR", Smerlak and Rovelli present a way of thinking about EPR which relies upon Rovelli's previously published work on relational ...
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Is Dr Quantum's Double Slit Experiment video scientifically accurate?

I'm fascinated by the fundamental questions raised by the Double Slit Experiment at the quantum level. I found this "Dr Quantum" video clip which seems like a great explanation. But is it ...
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2answers
363 views

Notation for Sections of Vector Bundles

(Reformulation of part 1 of Electromagnetic Field as a Connection in a Vector Bundle) I am looking for a good notation for sections of vector bundles that is both invariant and references bundle ...
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Does Quantum Physics really suggests this universe as a computer simulation? [closed]

I was reading about interesting article here which suggests that our universe is a big computer simulation and the proof of it is a Quantum Physics. I know quantum physics tries to provide some ...
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Electromagnetic Field as a Connection in a Vector Bundle

I would like to know more about Ehresmann connections in vector bundles and how they relate to the electromagnetic field and the electron in quantum mechanics. Background: The Schrödinger equation ...
4
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4answers
628 views

Are the physical laws scale-dependent?

If you read the article "More Is Different", by P.W. Anderson (Science, 4 August 1972), you will find a deep question: are the physical laws dependent of the size of the system under study? As an ...
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879 views

Evolution in the interpretation of the Dirac equation

As I understand, Dirac equation was first interpreted as a wave equation following the ideas of non relativistic quantum mechanics, but this lead to different problems. The equation was then ...
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682 views

Books for linear operator and spectral theory

I need some books to learn the basis of linear operator theory and the spectral theory with, if it's possible, physics application to quantum mechanics. Can somebody help me?
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596 views

Unambiguous distinguishing of quantum states by local measurement

Let's have two orthogonal n-particle quantum states: $|\psi \rangle$ and $|\phi \rangle$. In theory it is always possible to make an unambiguous measurement. However, things get complicated when one ...
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What are the most fundamental assumptions of quantum mechanics?

Can anybody give a list of the most fundamental assumptions of quantum mechanics in plain english ?
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What equation describes the wavefunction of a single photon?

The Schrödinger equation describes the quantum mechanics of a single massive non-relativistic particle. The Dirac equation governs a single massive relativistic spin-½ particle. The photon is a ...
15
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Nature of gravity: gravitons, curvature of space-time or both?

General relativity tells us that what we perceive as gravity is curvature of space-time. On the other hand (as I understand it) gravity can be understood as a force between objects which are ...
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A list of inconveniences between quantum mechanics and (general) relativity?

It is well known that quantum mechanics and (general) relativity do not fit well. I am wondering whether it is possible to make a list of contradictions or problems between them? E.g. relativity ...
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Why can't the outcome of a QM measurement be calculated a-priori?

Quantum Mechanics is very successful in determining the overall statistical distribution of many measurements of the same process. On the other hand, it is completely clueless in determining the ...
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The Many Body problem

(This is a simple question, with likely a rather involved answer.) What are the primary obstacles to solve the many-body problem in quantum mechanics? Specifically, if we have a Hamiltonian for a ...
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What are some useful ways to imagine the concept of spin as it relates to subatomic particles?

The answers in this question: What is spin as it relates to subatomic particles? do not address some particular questions regarding the concept of spin: How are some useful ways to imagine a ...
5
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2answers
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Deuterons can share quantum states, but why it is fine for the protons and neutrons inside?

Deuteron (2H) is composed of a neutron (spin-1/2) and a proton (spin-1/2), with a total spin of 1, which is a boson. Therefore, it is possible for two deuterons to occupy the same quantum state. ...
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Is (rest) mass quantized?

I learned today in class that photons and light are quantized. I also remember that electric charge is quantized as well. I was thinking about these implications, and I was wondering if (rest) mass ...
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10answers
925 views

Is quantum entanglement mediated by an interaction?

You can get two photons entangled, and send them off in different directions; this is what happens in EPR experiments. Is the entanglement then somehow affected if one puts a thick slab of EM ...
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1answer
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How do physicists use solutions to the Yang-Baxter Equation?

As a mathematician working the area of representation of Quantum groups, I am constantly thinking about solutions of the Yang-Baxter equation. In particular, trigonometric solutions. Often research ...
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10answers
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What is the difference between a measurement and any other interaction in quantum mechanics?

We've learned that the wave function of a particle collapses when we measure a particle's location. If it is found, it becomes more probable to find it a again in the same area, and if not the ...
25
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5answers
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Hamilton's Principle

Hamilton's principle states that a dynamic system always follows a path such that its action integral is stationary (that is, maximum or minimum). Why should the action integral be stationary? On ...