Quantum mechanics

In quantum mechanics and quantum field theory, the propagator is a function that specifies the probability amplitude for a particle to travel from one place to another in a given time, or to travel with a certain energy and momentum.

Electron diffraction refers to the wave nature of electrons.

In quantum mechanics, a parity transformation (also called parity inversion) is the flip in the sign of one spatial coordinate.

The path integral formulation of quantum mechanics is a description of quantum theory which generalizes the action principle of classical mechanics.

Quantum biology refers to applications of quantum mechanics and theoretical chemistry to biological objects and problems.

Quantum statistical mechanics is statistical mechanics applied to quantum mechanical systems.

Functional integration is a collection of results in mathematics and physics where the domain of an integral is no longer a region of space, but a space of functions.

In quantum chemistry and molecular physics, the Born–Oppenheimer (BO) approximation is the assumption that the motion of atomic nuclei and electrons in a molecule can be separated.

("Super atom" redirects here. For clusters of atoms that seem to exhibit some of the properties of elemental atoms, see Superatom.) A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero (that is, very near 0 K or −273.15 °C).

In quantum mechanics, bra–ket notation is a standard notation for describing quantum states.

A density matrix is a matrix that describes a quantum system in a mixed state, a statistical ensemble of several quantum states.

In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928.

In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals.

In mathematical physics and mathematics, the Pauli matrices are a set of three 2 × 2 complex matrices which are Hermitian and unitary.

The photoelectric effect or photoemission (given by Albert Einstein) is the production of electrons or other free carriers when light is shone onto a material.

The Planck constant (denoted h, also called Planck's constant) is a physical constant that is the quantum of action, central in quantum mechanics.

In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction.

In quantum mechanics, the uncertainty principle, also known as Heisenberg's uncertainty principle, is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which certain pairs of physical properties of a particle, known as complementary variables, such as position x and momentum p, can be known.

Identical particles, also called indistinguishable or indiscernible particles, are particles that cannot be distinguished from one another, even in principle.

In quantum mechanics, momentum (like all other physical variables) is defined as an operator, which "acts on" or pre-multiplies the wave function ψ(r, t) to extract the momentum eigenvalue from the wave function: the momentum vector a particle would have when measured in an experiment.

In physics, quantization is the process of transition from a classical understanding of physical phenomena to a newer understanding known as quantum mechanics.

In quantum physics, quantum state refers to the state of an isolated quantum system.

The transmission coefficient is used in physics and electrical engineering when wave propagation in a medium containing discontinuities is considered.

The mathematical formulations of quantum mechanics are those mathematical formalisms that permit a rigorous description of quantum mechanics.

Quantum numbers describe values of conserved quantities in the dynamics of a quantum system.

Quantum information science is an area of study based on the idea that information science depends on quantum effects in physics.

In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energies that an electron within the solid may have (called energy bands, allowed bands, or simply bands) and ranges of energy that it may not have (called band gaps or forbidden bands).

In quantum mechanics, the Hamiltonian is the operator corresponding to the total energy of the system in most of the cases.

The many-worlds interpretation is an interpretation of quantum mechanics that asserts the objective reality of the universal wavefunction and denies the actuality of wavefunction collapse.

Matrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925.

The multiverse (or meta-universe) is the hypothetical set of finite and infinite possible universes, including the universe in which we live.

Quantum tunnelling or tunneling (see spelling differences) refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount.

A potential well is the region surrounding a local minimum of potential energy.

The history of quantum mechanics is a fundamental part of the history of modern physics.

An ideal Bose gas is a quantum-mechanical version of a classical ideal gas.

In physics, the Clebsch–Gordan (CG) coefficients are numbers that arise in angular momentum coupling in quantum mechanics.

In physics, a pseudopotential or effective potential is used as an approximation for the simplified description of complex systems.

In physics, specifically in quantum mechanics, a coherent state is the specific quantum state of the quantum harmonic oscillator, often described as a state which has dynamics most closely resembling the oscillatory behavior of a classical harmonic oscillator.

Quantum mechanics is the science of the very small.

In pure and applied mathematics, particularly quantum mechanics and computer graphics and their applications, a spherical basis is the basis used to express spherical tensors.

Implicate order and explicate order are ontological concepts for quantum theory coined by theoretical physicist David Bohm during the early 1980s.

Magnetic resonance is a phenomenon that affects a Magnetic dipole when placed in a uniform static magnetic field.

Understanding the structure of the atomic nucleus is one of the central challenges in nuclear physics.

In physics, relativistic quantum mechanics (RQM) is any Poincaré covariant formulation of quantum mechanics (QM).

Symmetries in quantum mechanics describe features of spacetime and particles which are unchanged under some transformation, in the context of quantum mechanics, relativistic quantum mechanics and quantum field theory, and with applications in the mathematical formulation of the standard model and condensed matter physics.

In quantum mechanics, the angular momentum operator is one of several related operators analogous to classical angular momentum.

The quantum potential or quantum potentiality is a central concept of the de Broglie–Bohm formulation of quantum mechanics, introduced by David Bohm in 1952.

Quantum hydrodynamics is most generally the study of hydrodynamic systems which demonstrate behavior implicit in quantum subsystems (usually quantum tunnelling).

A quantum reference frame is a reference frame which is treated quantum theoretically.

In quantum mechanics, dynamical pictures (or representations) are the multiple equivalent ways to mathematically formulate the dynamics of a quantum system.

In relativistic quantum mechanics and quantum field theory, the Bargmann–Wigner equations (or BW equations or BWE) are relativistic wave equations which describe free particles of arbitrary spin j, an integer for bosons (j = 1, 2, 3 ...) or half-integer for fermions (j =  1⁄2,  3⁄2,  5⁄2 ...).

In mathematical physics, Clebsch–Gordan coefficients are the expansion coefficients of total angular momentum eigenstates in an uncoupled tensor product basis.

Retrocausality (also called retro-causation, retro-chronal causation, backward causation, and similar terms) is any of several hypothetical phenomena or processes that reverse causality, allowing an effect to occur before its cause.

Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave.

In theoretical physics, quantum geometry is the set of mathematical concepts generalizing the concepts of geometry whose understanding is necessary to describe the physical phenomena at distance scales comparable to Planck length.

In mathematics, the oscillator representation is a projective unitary representation of the symplectic group, first investigated by Irving Segal, David Shale, and André Weil.

In quantum mechanics, a translation operator is defined as an operator which shifts particles and fields by a certain amount in a certain direction.

The spin-stiffness or spin rigidity or helicity modulus or the "superfluid density" (for bosons the superfluid density is proportional to the spin stiffness) is a constant which represents the change in the ground state energy of a spin system as a result of introducing a slow in plane twist of the spins.

In pure and applied mathematics, quantum mechanics and computer graphics, a tensor operator generalizes the notion of operators which are scalars and vectors.