Quantum computing in a magnetic field: New ion trap for more qubits

A research group at ETH Zurich has taken on the limits of current quantum computers. One of the biggest challenges is the expansion to well over 100 qubits. Only some models with a few hundred qubits are actually in use at present. There are also setups with well over a thousand qubits, for example at the Jülich Research Center, Germany, but they have not yet been able to really show what they can do.

To counter this, the researchers have chosen a method that is as stable as possible and can be constructed with comparatively little effort. An ion trap with radio radiation can maintain stable quantum states and is therefore considered promising.

However, space is required for each of these traps, which ultimately represents a qubit. The source of the radio radiation requires a lot of energy. Interference between the circuits and the need for special materials also drive up costs, increase energy consumption and reduce efficiency.

This is to be countered by an ion trap that uses a magnetic field with a strength of 3 Tesla instead of radio radiation. This value is in the range of a typical magnetic resonance tomograph, i.e. quite high. Despite this, the trap constructed in this way should be extremely compact. The next step is to combine several similar structures into a more complex circuit.

The study published in Nature demonstrated https://www.nature.com/articles/s41586-024-07111-xfurther advantages of the method. Among other things, the magnetic field is equally strong across the entire ion trap, in contrast to radio radiation. This allows much better control of the ion. For example, the research team was able to move a single beryllium ion over an area just a few micrometers in size. Well over 100 different positions are possible on the surface.

Thanks to the flexible positioning, many other possible applications of the ion trap should be conceivable. Perhaps even a quantum computer one day, which, under acceptable conditions (size, efficiency), will bring with it the long-promised capabilities (really high performance).