名词解释量子物理.pdfVIP

Bras and kets: In quantum mechanics, Bra– ket notation is a standard notation for describing quantum states, composed of angle brackets and vertical bars. It c so be used to denote vectors and linear functional in mathematics. It is so called because the inner product (or dot product) of two states is denoted by a ⟨bra| ket⟩ Commutator: The commutator of two elements a and b of a ring or an associative algebra is defined by [a, b] = ab − ba. It is zero if and only if a and b commute. De Broglie wavelength: The wavelength of the wave associated with a particle as given by the de Broglie relation. λ = h/p Exclusion pr iple: The pr iple that no two fermions of the same kind may simultaneously occupy the same quantum state. Also known as Pauli Exclusion Pr iple. Expectation value: The average of the results of a large number of measurements of a ty made on a system in a given state; ase the measurement disturbs the state, the state is reprepared before ea easurement. Hamiltonian operator: symbol: H; a function used to express the total energy of a system in joules: H = T + V, where T is the k ic energy operator and V the potential energy operator. For a particle of mass m and momentum p, H = p2/2m + V. Hermitian operator: A linear operator A on vectors in a Hilbert space, such that if x and y are in the range of A then the inner products (Ax, y) and (x, Ay) are equal. Lagrangian : lassical mechanics, the natural form of the Lagrangian is defined as the k ic energy, T, of the system minus its potential energy, V. In symbols, L = T - V. Momentum space or k-space is the set of all wave vectors k, associated with particles - and bound. Orthonormal basis: In mathematics, particularly linear algebra, an orthonormal basis for an inner product space V with finite dimension is a basis for V who