Inseparable two spin-1/2 density matrices can be distilled to a singlet form

A quantum system is called inseparable if its density matrix cannot be written as a mixture of product states. In this Letter we apply the separability criterion, local filtering, and Bennett er al. distillation protocol [Phys. Rev. Lett. 76, 722 (1996)] to show that any inseparable 2 x 2 system represents the entanglement which, however small, can be distilled to a singlet form.