arXiv:2310.18528 · Journal of Physics A Mathematical and Theoretical
Nonuniform Bose–Einstein condensate: I. An improvement of the Gross–Pitaevskii method
Maksim Tomchenko
Abstract
Abstract A nonuniform condensate is usually described by the Gross–Pitaevskii (GP) equation, which is derived with the help of the c-number ansatz Ψ ^ ( r , t ) = Ψ ( r , t ) . Proceeding from a more accurate operator ansatz Ψ ^ ( r , t ) = a ^ 0 Ψ ( r , t ) / N , where N is the number of Bose particles, we find the equation i ℏ ∂ Ψ ( r , t ) ∂ t = − ℏ 2 2 m ∂ 2 Ψ ( r , t ) ∂ r 2 + ( 1 − 1 N ) 2 c Ψ ( r , t ) | Ψ ( r , t ) | 2 , which we call the GP N equation. It differs from the GP equation by the factor ( 1 − 1 /