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The Landau–Zener formula is an analytic solution to the equations of motion governing the transition dynamics of a two-state quantum system, with a time-dependent Hamiltonian varying such that the energy separation of the two states is a linear function of time. The formula, giving the probability of a diabatic (not adiabatic) transition ...
In quantum physics and quantum chemistry, an avoided crossing (AC, sometimes called intended crossing, [1] non-crossing or anticrossing) is the phenomenon where two eigenvalues of a Hermitian matrix representing a quantum observable and depending on continuous real parameters cannot become equal in value ("cross") except on a manifold of dimension . [2]
In quantum field theory, a branch of theoretical physics, crossing is the property of scattering amplitudes that allows antiparticles to be interpreted as particles going backwards in time. Crossing states that the same formula that determines the S-matrix elements and scattering amplitudes for particle to scatter with and produce particle and ...
The time interval may be controlled by a level crossing predictor, an electronic device which is connected to the rails of a railroad track, and activates the crossing's warning devices (lights, bells, gates, etc.) at a consistent interval prior to the arrival of a train at a level crossing. [1]
The amount of time light takes to travel one Planck length. quectosecond: 10 −30 s: One nonillionth of a second. rontosecond: 10 −27 s: One octillionth of a second. yoctosecond: 10 −24 s: One septillionth of a second. jiffy (physics) 3 × 10 −24 s: The amount of time light takes to travel one fermi (about the size of a nucleon) in a ...
To produce simple poles on boson frequencies =, either of the following two types of Matsubara weighting functions can be chosen () = = = (+ ()),() = = (),depending on which half plane the convergence is to be controlled in. () controls the convergence in the left half plane (Re z < 0), while () controls the convergence in the right half plane (Re z > 0).
The Planck time, denoted t P, is defined as: = = This is the time required for light to travel a distance of 1 Planck length in vacuum, which is a time interval of approximately 5.39 × 10 −44 s. No current physical theory can describe timescales shorter than the Planck time, such as the earliest events after the Big Bang. [ 30 ]
For instance, many times the time-based terms are placed first in the four-vectors, with the spatial terms following. Also, sometimes η is replaced with −η, making the spatial terms produce negative contributions to the dot product or spacetime interval, while the time term makes a positive contribution. These differences can be used in any ...