Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/35857
 Title: Micromotion in Trapped Atom-ion Systems Authors: LE HUY NGUYEN Keywords: Micromotion, atom ion interaction, trap, quantum gate, Paul trap, Floquet Issue Date: 6-Aug-2012 Citation: LE HUY NGUYEN (2012-08-06). Micromotion in Trapped Atom-ion Systems. ScholarBank@NUS Repository. Abstract: We examine the validity of the harmonic approximation, where the radio-frequency ion trap is treated as a harmonic trap, in the controlled collision of a trapped atom and a single trapped ion. This is equivalent to studying the effect of the micromotion since this motion must be neglected for the trapped ion to be considered as a harmonic oscillator. By applying the transformation of Cook \emph{et al.} we find that the micromotion can be represented by two periodically oscillating operators. In order to investigate the effect of the micromotion on the dynamics of a trapped atom-ion system, we calculate (i) the coupling strengths of the micromotion operators by numerical integration and (ii) the quasienergies of the system by applying the Floquet formalism, a useful framework for studying periodic systems. It turns out that the micromotion is not negligible when the distance between the atom trap and the ion trap is shorter than a characteristic distance. Within this range the energy diagram of the system changes dramatically when the micromotion is taken into account. The system exhibits chaotic behaviour through the appearance of numerous avoided crossings in the energy diagram when the micromotion coupling is strong. Excitation due to the micromotion leads to undesirable consequences for applications that are based on an adiabatic process of the trapped atom-ion system. We suggest a simple scheme for bypassing the micromotion effect in order to successfully implement a quantum-controlled phase gate proposed previously and create an atom-ion macromolecule. The methods presented in this thesis are not restricted to trapped atom-ion systems and can be readily applied to studying the micromotion effect in any system involving a single trapped ion. URI: http://scholarbank.nus.edu.sg/handle/10635/35857 Appears in Collections: Ph.D Theses (Open)

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