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  2. Perturbation theory (quantum mechanics) - Wikipedia

    en.wikipedia.org/wiki/Perturbation_theory...

    Perturbation theory is applicable if the problem at hand cannot be solved exactly, but can be formulated by adding a "small" term to the mathematical description of the exactly solvable problem. For example, by adding a perturbative electric potential to the quantum mechanical model of the hydrogen atom, tiny shifts in the spectral lines of ...

  3. Hand formula - Wikipedia

    en.wikipedia.org/wiki/Hand_formula

    In the case when the probability of loss is assumed to be a single number , and is the loss from the event occurring, the familiar form of the Hand formula is recovered. More generally, for continuous outcomes the Hand formula takes form: ∫ Ω L f ( L ) d L > B {\displaystyle \int _{\Omega }Lf(L)dL>B} where Ω {\displaystyle \Omega } is the ...

  4. Quantum jump method - Wikipedia

    en.wikipedia.org/wiki/Quantum_jump_method

    An example of the quantum jump method being used to approximate the density matrix of a two-level atom undergoing damped Rabi oscillations.The random jumps can clearly be seen in the top subplot, and the bottom subplot compares the fully simulated density matrix to the approximation obtained using the quantum jump method.

  5. Rectangular potential barrier - Wikipedia

    en.wikipedia.org/wiki/Rectangular_potential_barrier

    In classical wave-physics, this effect is known as evanescent wave coupling. The likelihood that the particle will pass through the barrier is given by the transmission coefficient, whereas the likelihood that it is reflected is given by the reflection coefficient. Schrödinger's wave-equation allows these coefficients to be calculated.

  6. De Broglie–Bohm theory - Wikipedia

    en.wikipedia.org/wiki/De_Broglie–Bohm_theory

    The situation is thus analogous to the situation in classical statistical physics. A low-entropy initial condition will, with overwhelmingly high probability, evolve into a higher-entropy state: behavior consistent with the second law of thermodynamics is typical. There are anomalous initial conditions that would give rise to violations of the ...

  7. Bethe–Salpeter equation - Wikipedia

    en.wikipedia.org/wiki/Bethe–Salpeter_equation

    The equation was first published in 1950 at the end of a paper by Yoichiro Nambu, but without derivation. [2] A graphical representation of the Bethe–Salpeter equation, showing its recursive definition. Due to its common application in several branches of theoretical physics, the Bethe–Salpeter equation appears in many forms.

  8. Quantum fluctuation - Wikipedia

    en.wikipedia.org/wiki/Quantum_fluctuation

    3D visualization of quantum fluctuations of the quantum chromodynamics (QCD) vacuum [1]. In quantum physics, a quantum fluctuation (also known as a vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space, [2] as prescribed by Werner Heisenberg's uncertainty principle.

  9. Uncertainty principle - Wikipedia

    en.wikipedia.org/wiki/Uncertainty_principle

    where = is the reduced Planck constant.. The quintessentially quantum mechanical uncertainty principle comes in many forms other than position–momentum. The energy–time relationship is widely used to relate quantum state lifetime to measured energy widths but its formal derivation is fraught with confusing issues about the nature of time.