Why geometric phase robust? Geometric phase is robust against classical fluctuation of the phase(of the first order)see for example G. D. Chiara. G. M. Palma, Phys. Rev Let.91,090404(2003) It is independent of systematic errors8 Why geometric phase robust? • Geometric phase is robust against classical fluctuation of the phase (of the first order) see for example: G. D. Chiara, G. M. Palma, Phys. Rev. Lett. 91, 090404 (2003). ◼It is independent of systematic errors