Learn more about the tools and methods we employ in our quantum computers and simulators.

Controlling individual atoms

Individually controlled atoms are at the heart of our quantum machines. We aim to trap and arrange hundreds of them atom-by-atom in arrays of optical tweezers formed by tightly focused laser beams. This architecture, pioneered by various groups in Europe and the USA, has seen a very rapid and dynamical development in the last years and now allows for realizing qubit arrays in 1D, 2D and even 3D geometries.

Laboratory with optical tables and two scientists

Trapping the atoms in focused light beams requires cooling them down to micro-Kelvin temperatures. At such low temperatures, the atoms move very slowly and are susceptible to the optical forces generated by the tweezers. Our machines are lab-scale setups which allow us to reach such ultralow temperatures via laser cooling.

The quantum computers and simulators developed in THE QUANTUM LÄND work with Strontium atoms. The atomic level structure of Strontium features narrow optical transitions associated with metastable excited electronic states. Alongside technical aspects such as motional sideband cooling, these states also provide promising means for encoding the computational qubit into the atom’s electronic levels with prospects to achieve coherence times beyond what is currently available.

Interacting Rydberg atoms

Having set up the qubit architecture, it is now essential to induce and control interactions between the atoms in the tweezer array. This can be achieved by exciting the atoms to Rydberg states using laser light. Rydberg atoms are highly excited atoms where the outermost electron is extremely far away from the atomic core. Accordingly, the atomic diameter is up to 10,000 times larger than that of an atom in its ground state. However, it is unlike an ion as the outer electron is not free but still bound to the atomic core, albeit extremely weakly.

Artistic rendering of four interacting Rydberg atoms

As a result, Rydberg atoms react sensitively to external electromagnetic stimuli and interact strongly and controllably with neighboring Rydberg atoms. This behavior provides the basis for the realization of fast quanutm logic gates or for using the strong interaction for quantum simulations.

We can built on more than 15 years of research on Rydberg atoms at the University of Stuttgart, comprising techniques to control their properties and interactions and to shield them from unwanted disturbances.