At the bank, there is a record of all the polarizations and the corresponding serial numbers. On the bank note, the serial number is printed, but the polarizations are kept secret. Thus, whilst the bank can always verify the polarizations by measuring the polarization of each photon in the correct basis without introducing any disturbance, a would-be counterfeiter ignorant of the bases cannot create a copy of the photon polarization states, since even if he knows the two bases, if he chooses the wrong one to measure a photon, it will change the polarization of the photon in the trap, and the forged banknote created will be with this wrong polarization.