The quantum force, which is the negative of the gradient of the quantum potential, can also be written in terms of the quantum pressure tensor: F Q = − − ∇ ∇ Q = − − m ρ ρ m ∇ ∇ ⋅ ⋅ p Q , where p Q = − − ( ℏ ℏ / 2 m ) 2 ρ ρ m ∇ ∇ ⊗ ⊗ ∇ ∇ ln ⁡ ⁡ ρ ρ m .