New architecture for quantum computing

Physicists at the University of Amsterdam have proposed a new architecture for a scalable quantum computer. By making use of the collective movement of particles, they have been able to build new building blocks for quantum computing that pose fewer technical difficulties than current state-of-the-art methods. The results were recently published in Physical Review Letters.

Researchers work at QuSoft and the Institute of Physics in the groups of Rene Gerritsma and Arghavan Safavi-Naini. The effort, led by PhD student Matteo Mazzanti, combines two important ingredients. The first is a so-called trapped ion platform, one of the most promising candidates for quantum computing that makes use of ions (atoms that have a surplus or shortage of electrons and are consequently electrically charged). The other is the use of an intelligent method to control the ions provided by optical tweezers and oscillating electric fields.

As the name suggests, trapped ion quantum computers use a crystal of trapped ions. These ions can move individually, but above all, also as a whole. Apparently, the possible collective movements of the ions facilitate interactions between the individual pairs of ions. In the proposal, this idea is made concrete by applying a uniform electric field to the entire crystal, in order to mediate the interactions between two specific ions in that crystal.



A quantum computer is made up of "Doors", small computational building blocks that execute quantum analogs of operators like "and" and "o" that we know from ordinary computers. In trapped ion quantum computers, these gates act on the ions and their functioning depends on the interactions between these particles.

The fact that these interactions do not depend on the distance means that the duration of the operation of a gate is also independent of this distance. Consequently, this scheme for quantum computing is inherently scalable and, compared to other state-of-the-art quantum computing schemes, poses fewer technical challenges to obtain relatively well-functioning quantum computers.