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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]
The model can answer questions such as the probability that this occurs within finite time, or the mean time until which it occurs. First-hitting-time models can be applied to expected lifetimes, of patients or mechanical devices. When the process reaches an adverse threshold state for the first time, the patient dies, or the device breaks down.
The most important inference derived from the steady state equation and the equation for fractional change over time is that the elimination rate constant (k e) or the sum of rate constants that apply in a model determine the time course for change in mass when a system is perturbed (either by changing the rate of inflow or production, or by ...
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 ...
Suppose that we can switch on a time-varying, spatially constant field () which alters the Hamiltonian to () = (). The response of the observable x ( t ) {\displaystyle x(t)} to a time-dependent field f ( t ) {\displaystyle f(t)} is characterized to first order by the susceptibility or linear response function χ ( t ) {\displaystyle \chi (t ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
In the k-calculus methodology, distances are measured using radar.An observer sends a radar pulse towards a target and receives an echo from it. The radar pulse (which travels at , the speed of light) travels a total distance, there and back, that is twice the distance to the target, and takes time , where and are times recorded by the observer's clock at transmission and reception of the ...