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  2. Kronecker delta - Wikipedia

    en.wikipedia.org/wiki/Kronecker_delta

    The Kronecker delta has the so-called sifting property that for : = =. and if the integers are viewed as a measure space, endowed with the counting measure, then this property coincides with the defining property of the Dirac delta function () = (), and in fact Dirac's delta was named after the Kronecker delta because of this analogous property ...

  3. Levi-Civita symbol - Wikipedia

    en.wikipedia.org/wiki/Levi-Civita_symbol

    A tensor whose components in an orthonormal basis are given by the Levi-Civita symbol (a tensor of covariant rank n) is sometimes called a permutation tensor. Under the ordinary transformation rules for tensors the Levi-Civita symbol is unchanged under pure rotations, consistent with that it is (by definition) the same in all coordinate systems ...

  4. Canonical commutation relation - Wikipedia

    en.wikipedia.org/wiki/Canonical_commutation_relation

    According to the correspondence principle, in certain limits the quantum equations of states must approach Hamilton's equations of motion.The latter state the following relation between the generalized coordinate q (e.g. position) and the generalized momentum p: {˙ = = {,}; ˙ = = {,}.

  5. Exchange operator - Wikipedia

    en.wikipedia.org/wiki/Exchange_operator

    In quantum mechanics, the exchange operator ^, also known as permutation operator, [1] is a quantum mechanical operator that acts on states in Fock space. The exchange operator acts by switching the labels on any two identical particles described by the joint position quantum state | x 1 , x 2 {\displaystyle \left|x_{1},x_{2}\right\rangle } . [ 2 ]

  6. Commutation matrix - Wikipedia

    en.wikipedia.org/wiki/Commutation_matrix

    # Kronecker delta def delta (i, j): return int (i == j) def comm_mat (m, n): # determine permutation applied by K v = [m * j + i for i in range (m) for j in range (n)] # apply this permutation to the rows (i.e. to each column) of identity matrix I = [[delta (i, j) for j in range (m * n)] for i in range (m * n)] return [I [i] for i in v]

  7. Symmetry in quantum mechanics - Wikipedia

    en.wikipedia.org/wiki/Symmetry_in_quantum_mechanics

    where δ ij is the Kronecker delta, and ε ijk is the Levi-Civita symbol. It is not as obvious how to determine the rotational operator compared to space and time translations. We may consider a special case (rotations about the x , y , or z -axis) then infer the general result, or use the general rotation matrix directly and tensor index ...

  8. Wave function - Wikipedia

    en.wikipedia.org/wiki/Wave_function

    In quantum physics, a wave function (or wavefunction) is a mathematical description of the quantum state of an isolated quantum system. The most common symbols for a wave function are the Greek letters ψ and Ψ (lower-case and capital psi , respectively).

  9. Greek letters used in mathematics, science, and engineering

    en.wikipedia.org/wiki/Greek_letters_used_in...

    the Kronecker delta function; the Feigenbaum constants; the force of interest in mathematical finance; the Dirac delta function; the receptor which enkephalins have the highest affinity for in pharmacology [1] the Skorokhod integral in Malliavin calculus, a subfield of stochastic analysis; the minimum degree of any vertex in a given graph