Institute of Solid State Physics

SS20WS20SS21WS21SS22WS22SS23      Guidelines for Master Students

Dielectric Properties of Plasma Oxides for Microfabricated Ion Traps
Alexander Zesar
11:15 - 12:15 Wednesday 14 April 2021 

Today classical electronic computers are in use in almost every imaginable application. A now emerging paradigm shift in computation is called "quantum computing", which enables a considerable increase in speed for many important problems in science and technology that have been intractable using conventional methods. One example for such a problem is integer factorization implemented by Shor's quantum algorithm, being almost exponentially faster than classical counterparts.

Trapped ions are a promising technical realization of a feasible quantum processor, where stored ions represent physical quantum bits (qubits). Qubits are manipulated by quantum gate operations that ultimately enable quantum information processing. Quantum computers using trapped ions have already been shown to successfully implement quantum algorithms (including Shor's), quantum simulations and error correction.

The path towards a practical and universal quantum computer unavoidably includes an upscaling of its qubit number, which today poses a considerable engineering challenge. Current traps can reliably store a few tens of ions, while the ultimate goal is an increase of the qubit number by a few orders of magnitude.

Microfabricated ion traps with 18 trapping sites are in development at Infineon, Villach [arXiv:2003.08085]. Surface electrodes produce an electromagnetic stray field that confines the ions a few tens of microns above the trap. By varying the field, the ion's positions are controlled (ion shuttling) to allow specific local interactions. Currently one major obstacle for upscaling to higher qubit numbers in the described trap design is heat dissipation. This is mainly caused by radiofrequency losses in dielectric materials and ohmic losses due to charge currents of parasitic capacitances. The aim of the present work is to characterize dielectric losses in plasma oxides and find possible ways to reduce them.

Firstly, this talk will give a short overview of trapped ion quantum computing with microfabricated ion traps and what obstacles need to be overcome to increase the qubit number. Secondly, I will outline the current status of my experiments to investigate dielectric properties of plasma oxides in the optical and RF frequency range. Furthermore, the talk will discuss the effects of different thermal treatments on plasma oxides especially regarding their dielectric properties in the radiofrequency regime. The talk will be concluded with a vision of future quantum processors with thousands of qubits.