We show how to generate quasi-rectangle-states of the vibrational motion of an ion, this is, states that have the same probability in a given position interval. We produce those states by repeated ionlaser interactions followed by conditional measurements that generate a superposition of squeezed states. The squeeze parameter of the initial state may be tuned in order to obtain such highly localized rectangle states.
I. INTRODUCTIONThe early papers of Roy Glauber [1, 2] on coherence, marked a course on how to define nonclassical states, a first good approximation was: Those states that have less fluctuations in a given observable than that of a coherent state [2]. Since then, a myriad of ways of generating nonclassical states, theoretically and experimentally, have been proposed [3][4][5][6][7][8][9][10][11].Nonclassical states of the centre-of-mass motion of a trapped ion have played an important role because of fundamental problems in quantum mechanics and for their potential practical applications such as precision spectroscopy [3] and quantum computation [4,5]. By exhibiting less fluctuations than that of a coherent state, the so-called standard quantum limit they are of great importance.Ways of generating squeezed states [6], superpositions of coherent states [7,8], nonlinear coherent states [9-11], number states and some specific superpositions of them have been proposed [12]. In experimental and theoretical studies of single trapped ions interacting with laser beams it has been usually considered the case in which such interaction may be modeled as a Jaynes-Cummings interaction [6,13,14], therefore exhibiting collapses and revivals [15] and the generation of nonclassical states, peculiar of such a model, or its multiphotonic generalizations [16][17][18]. It should be noted also that, via a similarity transformation that does not need of any approximations, the ion-laser interaction may be taken to a two-level atom interacting with a quantized field, i.e., the Rabi interaction [19][20][21]. In fact multiphonon Rabi models may be realized via such transformation [22].When studying ion-laser interactions, usually two rotating wave approximations are performed, the first related to the laser optical frequency and the second to the vibrational frequency of the ion, in order to remove counterpropagating terms of the Hamiltonian, difficult to be treated analytically. Approximations on the Lamb-Dicke parameter, η, are usually done, considering it much smaller than unity. In order to perform the rotating wave approximation, the laser intensity, Ω, is considered much smaller than the trapping frequency, ν, namely Ω ν [23]. As mentioned above, cavity fields and trapped ions share several common features as in both topics the possibility to realize Jaynes-Cummings [24,25] and anti-Jaynes-Cummings [26] interactions, are feasible. In cavities interacting with atoms this model describes the resonant or slightly non-resonant interaction of an atom with the cavity mode [27]. On the other hand, for a trapped ion in the Lamb...