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Level Repulsion
Level repulsion is the quantum mechanical Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ... equivalent to a repulsion effect in oscillators. A system of two coupled oscillators has two natural frequencies. As the coupling strength between the oscillators increases, the lower frequency decreases and the higher increases. See also * Avoided crossing * Intersubband polariton * Wigner–Ville distribution References Quantum mechanics {{Quantum-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanical
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary ( macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale. Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values ( quantization); objects have characteristics of both particles and waves (wave–particle duality); and there are limits to ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscillator
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy. The term ''vibration'' is precisely used to describe a mechanical oscillation. Oscillation, especially rapid oscillation, may be an undesirable phenomenon in p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avoided Crossing
In quantum physics and quantum chemistry, an avoided crossing (sometimes called intended crossing, ''non-crossing'' or anticrossing) is the phenomenon where two eigenvalues of an Hermitian matrix representing a quantum observable and depending on ''N'' continuous real parameters cannot become equal in value ("cross") except on a manifold of ''N''-2 dimensions. The phenomenon is also known as the von Neumann–Wigner theorem. In the case of a diatomic molecule (with one parameter, namely the bond length), this means that the eigenvalues cannot cross at all. In the case of a triatomic molecule, this means that the eigenvalues can coincide only at a single point (see conical intersection). This is particularly important in quantum chemistry. In the Born–Oppenheimer approximation, the electronic molecular Hamiltonian is diagonalized on a set of distinct molecular geometries (the obtained eigenvalues are the values of the adiabatic potential energy surfaces). The geometries for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersubband Polariton
Intersubband transitions (also known as intraband transitions) are dipolar allowed optical excitations between the quantized electronic energy levels within the conduction band of semiconductor heterostructures. Intersubband transitions when coupled with an optical resonator form new, mixed-state photons. This mixing is referred to as an intersubband cavity-polariton. These transitions exhibit an anticrossing in energy with a separation known as vacuum-Rabi splitting, similar to level repulsion in atomic physics. Quantum cascade laser A cascading of intersubband transitions is the mechanism behind a quantum cascade laser which produces a monochromatic coherent light-source at infrared wavelengths. Color of metals Most metals reflect almost all visible light, due to the presence of free charges, and are therefore silvery in color or mirror-like. However, some metals like gold and copper are more reddish, and this is due to absorption from intersubband transitions that occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wigner–Ville Distribution
The Wigner quasiprobability distribution (also called the Wigner function or the Wigner–Ville distribution, after Eugene Wigner and Jean-André Ville) is a quasiprobability distribution. It was introduced by Eugene Wigner in 1932 to study quantum corrections to classical statistical mechanics. The goal was to link the wavefunction that appears in Schrödinger's equation to a probability distribution in phase space. It is a generating function for all spatial autocorrelation functions of a given quantum-mechanical wavefunction . Thus, it maps on the quantum density matrix in the map between real phase-space functions and Hermitian operators introduced by Hermann Weyl in 1927, in a context related to representation theory in mathematics (see Weyl quantization). In effect, it is the Wigner–Weyl transform of the density matrix, so the realization of that operator in phase space. It was later rederived by Jean Ville in 1948 as a quadratic (in signal) representation of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
