Definition: In quantum mechanics, the momentum operator is the operator associated with the linear momentum. The momentum operator is, in the position representation, an example of a differential operator.
Area: quantum mechanics
Symbol: $\widehat{\boldsymbol{p}}$
SI Unit: $\text{J s m}^{-1}$
Wikidata entry: Q692457
Data from Wikidata

• Dimensionality: $\mathsf{L} \mathsf{M} \mathsf{T}^{-1}$
• Equation: $\widehat{\boldsymbol{p}}=-{\rm i}\hbar\; \boldsymbol{\nabla}$
• Variables:
  • momentum operator: $\widehat{\boldsymbol{p}}$
  • imaginary unit: ${\rm i}$
  • reduced Planck constant: $\hbar$
  • nabla operator: $\boldsymbol{\nabla}$

Notes

• The circumflex (or "hat"), $\widehat{}$, serves to distinguish an operator from an algebraic quantity. This definition applies to a coordinate representation, where $\boldsymbol{\nabla}$ denotes the nabla operator (see Section 4.2, p. ??)