In the world of computing, we usually think of information as being stored as ones and zeros – also known as binary notation. However, in our daily life, we use ten digits to represent all possible numbers. In the binary system, the number 9 is written as 1001 for example, which would require three additional digits to represent the same thing.
Today’s quantum computers arose from this binary model, but in fact, physical systems that encode quantum bits (qubits) often also have the ability to encode quantum numbers (qudits), as recently demonstrated by a team led by Martin Ringbauer at the University of Innsbruck’s Department of Experimental Physics. According to experimental physicist Pavel Hrmo from ETH Zurich: “The challenge for qudit-based quantum computers is to create efficient entanglement between high-dimensional information carriers.”
In a study published in the journal Nature Communications The University of Innsbruck team has now reported how two codecs can fully entangle each other with unprecedented performance, paving the way for more efficient and powerful quantum computers.
Thinking like a quantum computer
The example of the number 9 shows that while humans are able to calculate 9 x 9 = 81 in one step, a classical computer (or calculator) must take 1001 x 1001 and do many steps of double multiplication behind the scenes before it is able to display 81 on the screen. Conventionally, we can afford to do this, but in the quantum world where computations are inherently sensitive to external noise and perturbations, we need to reduce the number of operations required to make the most of the available quantum computers.
Quantum entanglement is crucial to any computational operation on a quantum computer. Entanglement is a unique quantum feature that underpins the potential for quantum computers to significantly outperform classical computers at certain tasks. However, exploiting this potential requires robust and precise high-dimensional entanglement generation.
The natural language of quantum systems
Researchers at the University of Innsbruck have now managed to entangle two codons, each encoded in up to 5 states of individual calcium ions. This gives theoretical and experimental physicists a new tool to bypass binary information processing, which could lead to faster and more powerful quantum computers.
Martin Ringbauer explains: “Quantum systems have many more available states waiting to be used in quantum computing, rather than being restricted to working with qubits.” Many of today’s most challenging problems, in fields as diverse as chemistry, physics, or optimization, can take advantage of this natural language of quantum computing.
The research was financially supported by the Austrian Science Fund FWF, the Austrian Research Promotion Agency FFG, the European Research Council ERC, the European Union and the Confederation of Austrian Industries Tyrol, among others.