Thirty Years of Ion-Trap Computing TooJ. Ignacio Cirac

In 1994, at the Atomic Physics Conference in Boulder, Arthur Ekert delivered a pivotal plenary talk on quantum computing. He explained the concept and introduced Shor’s groundbreaking quantum algorithm for factoring, which had been developed just months prior. While Arthur Ekert conveyed the excitement surrounding the field, the practicality of building a quantum computer remained a tantalizing uncertainty. He posed the question of how to build a quantum computer to the audience, challenging them to find a way forward.

It was in this very moment, while Peter Zoller and I were attending the talk in Boulder, that sparked our interest on that question. Our solution emerged a few months later in the form of an ion trap quantum computer. We had already been immersed in the study of quantum phenomena within ion trap systems, albeit with a single ion. We understood their capacity to store a qubit in their internal states, which one could manipulate using lasers. Moreover, we also knew how to initialize it and read out the information from it. However, we did not know how to implement quantum gates between the ions. The primary hurdle for us lay in orchestrating interactions between different ions to produce those gates. In this talk, I will delineate the origin of our ideas, the venues where we first unveiled them, and how the team led by David Wineland and Christopher Monroe executed the initial experimental demonstration. I will also recount how Rainer Blatt’s group and others propelled these concepts further, culminating in the construction of different prototypes of quantum computers.