EntityQ3277876· pop 8· linked from 26 articlesparticle number operatorSign in to saveoperator in quantum mechanics whose eigenvalues label states with the number of particles in the system in those statesConnectionsquantum mechanicsEntityInternational Standard Book NumberEntitythermodynamicsEntityquantum field theoryEntitybasisEntityharmonic oscillatorEntitybra–ket notationEntityquantum harmonic oscillatorEntityobservableEntityFock spaceEntitysecond quantizationEntitycreation and annihilation operatorsEntityFock stateEntitynumber of particlesEntityCategoriesQuantum operators