Ramsey fringes, optical

In the previous sections we discussed how the interaction time of atoms or ions with laser fields can be greatly increased by cooling and trapping. Optical cooling cannot be applied to molecules, which do not represent two-level systems. Here another technique has been developed that increases the interaction time of atoms or molecules with EM fields by increasing the spatial interaction zone and thus decreasing the transit-time broadening of absorption lines (Sect. 3.4). 

The basic idea of a quantum computer needs the realization of entangled states. Such states are the coherent superposition of real atomic states. An entangled state of an atom with two hyperfine levels 0) and 11) is for instance the state 

This entangled state is named quantum bit or q-bit. It replaces the bits 0 and T of the classical computer. 

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Some techniques of laser spectroscopy, such as the method of separated fields optical Ramsey fringes. Sect. 9.4), coherent transient spectroscopy (Sect. 7.6), or polarization spectroscopy (Sect. 2.4) allow one to distinguish between phasechanging, velocity-changing, or orientation-changing collisions. 

The capability of this combination of saturation spectroscopy with optical Ramsey fringes has been demonstrated by Bergquist et al. [1265] for the example of the neon transition Iss 2p2 atk = 588.2 nm (Fig. 9.61). A linewidth of 4.3 MHz for... 

C.J. Borde, C. Salomon, S.A. AvriUier, A. Van Lerbeighe, C. Breant, D. Bassi, G. Scoles, Optical Ramsey fringes with travelling waves. Phys. Rev. A 30,1836 (1984)... 

J. Helmcke, D. Zevgolis, B.U. Yen Observation of high contrast ultra narrow optical Ramsey fringes in saturated absorption utilizing four interaction zones of travelling waves. Appl. Rhys. B 28, 83 (1982)... 

Fig.9.51. Illustration of the optical Ramsey fringe technique in the time domain [9.210]...

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