Creation of arbitrary coherent superposition states by stimulated Raman adiabatic passage

Abstract

A technique for creation of well-defined preselected coherent superpositions of multiple quantum states is proposed. It is based on an extension of the technique of stimulated Raman adiabatic passage ͑STIRAP͒ to degenerate levels. As an example, the nine-state system composed of the magnetic sublevels of three levels with angular momenta J g =0, J e = 1, and J f = 2 is studied in detail. Starting from the ͉J g =0, M g =0͘ state, STIRAP can create an arbitrary preselected coherent superposition between the five M f sublevels ͑M f =−2,−1,0, +1, +2͒ of the J f = 2 level with 100% efficiency in the adiabatic limit. The populations and the phases of the M f states in this superposition are determined entirely by the polarizations of the two laser fields. It is shown that this technique allows one to create any superposition of the five M f states, that is, to reach any point in the Hilbert space of the J f = 2 manifold, and the corresponding recipes for choosing the laser polarizations are presented.

Coherent superposition of M-states in a single rovibrational level of H2 by Stark-induced adiabatic Raman passage

“…Similar perpendicular propagation of the pump and Stokes lasers has been used by STIRAP to achieve M-sublevel superpositions. 5,6 In essence such coher- ent superposition is equivalent to a molecular interferometer for the incident flux of particles whose scattering will be determined by the phase of the scatterer. The present technique of preparing an M-sublevel superposition of molecules like H 2 finally opens the possibility to measure the phase of the reaction amplitude.…”

“…This is because, in the collision-free ambience of a molecular beam, traditional off-resonant Raman pumping has been unsuccessful in preparing a rovibrational quantum state for a sizable population of H 2. 3, 4 Likewise, the resonantly enhanced Raman adiabatic techniques such as the stimulated Raman adiabatic passage (STIRAP) 5,6 and, Stark chirped Raman adiabatic passage (SCRAP), [7][8][9] are not suitable to prepare quantum states of H 2 because of the wide energy gap between the ground state and accessible excited electronic states. To prepare hydrogen molecules using these resonant techniques, the requirement of appropriate VUV laser sources and ionization loss poses a practical challenge.…”

Robust switching of superposition-states via a coherent double stimulated Raman adiabatic passage

“…Here we assume ∆P t=0 ab ≥ 0. Such a superposition state can be yielded by rotation of single state through the ways of adiabatic passage [29][30][31][32] or spontaneous radiation [33]. Atoms of b-state will experience an ordinary d-STIRAP process which is irrelevant to the spontaneous loss from the intermediate state |m .…”

Creation of coherent superposition states in inhomogeneously broadened media with relaxation

“…Other, more robust schemes for creation of coherent superposition states were proposed in the last decade in atomic and molecular systems with more complicated structure of working levels. The majority of these schemes are based on the adiabatic following method, which is robust against small-to-medium variations of the parameters of the laser fields [18][19][20][21][22][23][24][25][26][27][28][29]. The mostly used schemes of the adiabatic following include stimulated Raman adiabatic passage (STIRAP) [18][19][20][21][22][23][24][25][26], Stark chirped rapid-adiabatic passage (SCRAP) [27][28][29] and schemes involving frequency modulated (chirped) laser radiation [9,[30][31][32][33][34][35][36][37][38].…”