Most quantum computers use binary encoding to store information in qubits—the quantum analog of classical bits 0 or 1. Restricting them to binary systems prevents these devices from living up to their true potential.

Keeping it in mind, a team led by Thomas Monz at the Department of Experimental Physics at the University of Innsbruck has successfully developed a quantum computer that can perform arbitrary calculations with so-called quantum digits (qudits).

With performance similar to qubit quantum processors, this approach enables the native simulation of high-dimensional quantum systems and more efficient implementation of qubit-based algorithms.

This new quantum computer stores information in individual trapped Calcium atoms. Each atom consists of eight different states. Typically only two among these states are used to store information. Indeed, almost all existing quantum computers have access to more quantum states than they use for computation.

Thomas Monz said, “Almost all existing quantum computers have access to more quantum states than they use for computation. We developed a quantum computer that can use these atoms’ full potential by computing with qudits. Contrary to the classical case, using more states does not make the computer less reliable. Quantum systems naturally have more than two states, and we showed that we can control them all equally well.”

Martin Ringbauer, an experimental physicist from Innsbruck, Austria, said, “On the flipside, many of the tasks that need quantum computers, such as problems in physics, chemistry, or material science, are also naturally expressed in the qudit language. Rewriting them for qubits can often make them too complicated for today’s quantum computers. Working with more than zeros and ones is very natural, not only for the quantum computer but also for its applications, allowing us to unlock the true potential of quantum systems.”

Journal Reference:

  1. Ringbauer, M., Meth, M., Postler, L. et al. A universal qudit quantum processor with trapped ions. Nat. Phys. (2022). DOI: 10.1038/s41567-022-01658-0