Doctoral defence: Elena Vinogradova "Optical centers and quantum entangled states of Nd3+ ions in doped fluoride crystals“

On 22 August at 14:15 Elena Vinogradova will defend her doctoral thesis „Optical centers and quantum entangled states of Nd³⁺ ions in doped fluoride crystals“ for obtaining the degree of Doctor of Philosophy (in Materials Science).

Supervisors:

Associate Professor Yury Orlovskiy, University of Tartu
Associate Professor Viktor Peet, University of Tartu
PhD Ilmo Sildos, University of Tartu

Opponent:
professor Sergey Sekatskii, École Polytechnique Fédérale de Lausanne (Switzerland)

Summary

Fluoride crystals and their nanoparticles activated by rare-earth ions (REIs) are of great interest for both fundamental and applied science, where several applications in optics, laser technologies, and photonics have emerged during last decades. A novel and very promising area for these materials is the development of ultra-fast optical quantum computers where the REIs-based optical centers can serve as basic qubits. In this context, the study of formation and properties of different types of REI optical centers is of great interest. In this thesis, different types of fluoride crystals doped with Nd³⁺ ions were studied using site-selective time-resolved laser spectroscopy at liquid helium temperatures. It was shown that there is a complex set of optical centers depending on the crystal host. In the crystals of fluorite structure where the Nd3+ ions and nearby charge compensating F^- ions are located, very different optical centers with unique properties are formed. Spectral and kinetic properties of various optical centers were studied in detail. Several new previously undiscovered types of optical centers were identified and described. A two-color laser excitation scheme was used to study the interacting optical centers consisting of two closely-spaced REIs. It was shown that for such pair centers it is possible to create so called quantum entangled cooperative states, which could be used as building blocks for future quantum computers. Thus, the results of the dissertation make a valuable contribution to this topical and rapidly developing field of modern science and technology.

Defence can be also followed in Teams.