Microfabricated Optics for Quantum Control of Trapped Ions

  • Matthew Day

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Trapped ions have been established as a useful resource for a number of quantum protocols. In all applications, from precision timing to quantum information processing, it is beneficial to increase the number of trapped ions in one system. Microfabricated ion microtrap arrays have provided a
route to scaling the number of trapped ions, however a corresponding scalable optical interface for coupling to the electronic and motional states of the ions has not yet been realised. One identified technique to scaling the optics is to use microfabrication techniques. Microfabricated optics have been previously coupled to trapped ions, either for imaging or laser beam addressing, however no complete architecture has been realised, with the state of the art being the addressing of a single ion trap segment with a single beam of red wavelength. In this thesis, we propose and develop a novel micro-optical assembly for laser beam addressing and ion fluorescence collection of multiple ion microtrap segments. The assembly is composed of fibre, laser-written waveguide and diffractive microlens arrays for delivering laser beams from blue to near-IR wavelengths with the correct kvectors to drive electronic and motional transitions in 88Sr+ ions, as well as collecting the resulting blue wavelength fluorescence. The realisation of the optical assembly required the development of laser-written waveguides for guiding blue wavelengths, as well as efficient on and off-axis diffractive microlenses. The developed optical components allowed the fabrication of a demonstrator optical assembly for delivering three blue wavelength beams and two near-IR wavelength beams to two spatially separated points in space corresponding to the centres of two microtrap segments. The
fabricated assembly has high transmission, accurate beam pointing and low crosstalk which supports the future viability of the platform.
Date of Award6 Nov 2018
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorGraham Marshall (Supervisor) & Alastair G. Sinclair (Supervisor)

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