# Optical control and quantum information processing with ultracold alkaline-earth-like atoms

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/10334

# Optical control and quantum information processing with ultracold alkaline-earth-like atoms

 dc.contributor.author Reichenbach, Iris Evelyn Nicole dc.date.accessioned 2010-02-09T21:50:15Z dc.date.available 2010-02-09T21:50:15Z dc.date.issued 2010-02-09T21:50:15Z dc.date.submitted December 2009 dc.identifier.uri http://hdl.handle.net/1928/10334 dc.description.abstract Ultracold neutral atoms in optical lattices are rich systems for the investigation of many-body physics as well as for the implementation of quantum information processing. While traditionally alkali atoms were used for this research, in recent years alkaline-earth-like atoms have attracted considerable interest. This is due to their more complex but tractable internal structure and easily accessible transitions. Furthermore, alkaline-earth-like atoms have extremely narrow ${}^1S\rightarrow{}^3P$ intercombination transitions, which lend themselves for the implementation of next generation atomic clocks. en_US In this dissertation, I show that exquisite control of alkaline-earth-like atoms can be reached with optical methods, and elucidate ways to use this controllability to further different aspects of research, mainly quantum information processing. Additionally, the control of alkaline-earth-like atoms is very interesting in many-body physics and the improvement of atomic clocks. Since heating usually degrades the performance of quantum gates, recooling of qubits is a necessity for the implementation of large scale quantum computers. Laser cooling has advantages over the usually used sympathetic cooling, given that it requires no additional atoms, which have to be controlled separately. However, for qubits stored in hyperfine states, as usually done in alkali atoms, laser cooling leads to optical pumping and therefore to loss of coherence. On the other hand, in the ground state, the nuclear spin of alkaline-earth-like atoms is decoupled from the electronic degrees of freedom. As I show in this dissertation, this allows for the storage of quantum information in the nuclear spin and laser cooling on the electronic degrees of freedom. The recooling protocol suggested here consists of two steps: resolved sideband cooling on the extremely narrow ${}^1S_0\rightarrow {}^3P_0$ clock transition and subsequent quenching on the much shorter lived ${}^1P_1$ state. A magnetic field is used to overcome the hyperfine interaction in this excited state and thus ensures decoupling of the nuclear spin degrees of freedom during the quenching. The application of this magnetic field also allows for photon scattering on the ${}^1P_1$ state, while preserving the nuclear spin, e. g. for electronic qubit detection. The manipulation of the scattering properties of neutral atoms is an important aspect of quantum control. In contrast to alkali atoms, whose broad linewidths cause large losses, this can be done with purely optical methods via the implementation of an optical Feshbach resonance for alkaline-earth-like atoms. Here, the scattering length resulting from the application of an optical Feshbach resonance on the ${}^1S_0\rightarrow {}^3P_1$ intercombination line, including hyperfine interaction and rotation is calculated for ${}^{171}$Yb. Due to their different parities, the p-wave scattering length can be controlled independently from the s-wave scattering length, thus allowing for unprecedented control over the scattering properties of neutral atoms. Furthermore, I also show how optical Feshbach resonances in alkaline-earth-like atoms can be used together with the underlying quantum symmetry to implement collisional gates between nuclear-spin qubits over comparatively long ranges. dc.description.sponsorship Office of Naval Research en_US Intelligence Advanced Research Projects Activity dc.language.iso en_US en_US dc.subject Quantum information processing en_US dc.subject alkaline-earth atoms en_US dc.subject optical Feshbach resonances en_US dc.subject Quantum Control en_US dc.subject Quantum Optics en_US dc.subject ultracold atoms en_US dc.subject.lcsh Quantum computers--Materials. dc.subject.lcsh Atomic clocks--Materials. dc.subject.lcsh Optical resonance. dc.subject.lcsh Quantum optics. dc.subject.lcsh Ytterbium. dc.title Optical control and quantum information processing with ultracold alkaline-earth-like atoms en_US dc.type Dissertation en_US dc.description.degree PhD en_US dc.description.level Doctoral en_US dc.description.department University of New Mexico. Dept. of Physics & Astronomy en_US dc.description.advisor Deutsch, Ivan H. dc.description.committee-member Caves, Carlton M. dc.description.committee-member Prasad, Sudhakar dc.description.committee-member Evans, Deborah G. dc.description.committee-member Julienne, Paul S.
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