As we have known for a long time, digital computers work on the principle of zeros and ones, also known as binary information. This approach has always worked well. In fact, it’s been so successful that computers now power everything from coffee machines to self-driving cars, and it’s hard to imagine life without them.
Building on this incredible success, today’s quantum computers were also developed on the basis of binary information processing. “The building blocks of quantum computers are not just zeros and ones, however,” explains Martin Limbauer, an experimental physicist from Innsbruck, Austria.” Restricting them to binary systems prevents these devices from reaching their true potential.”
A team of scientists has now succeeded in developing a quantum computer that can perform arbitrary calculations with so-called quantum bits (qudits), thereby unleashing additional computing power with fewer quantum particles. The group is led by Thomas Muntz of the Department of Experimental Physics at the University of Innsbruck.
Storing information in zeros and ones is not the most efficient way to compute, but it is the simplest. Simplicity also usually means reliability and reduced errors, which is why binary information has become the unquestioned standard for classical computers.
Quantum physicist Martin Limbauer in his lab
In the quantum world, however, the situation is quite different. For example, in Innsbruck’s quantum computer, information is stored in individually trapped calcium atoms. Each of these atoms naturally has eight different states, only two of which are normally used to store information. In fact, almost all existing quantum computers have access to more quantum states than they actually use for computing.
Physicists from Innsbruck have now designed a quantum computer that can take full advantage of the full potential of these atoms by using quantum bits for computation. In contrast to the classical case, using more states in this case does not make the computer any less reliable.” Thomas Muntz says, “Quantum systems naturally have more than two states, and we show that we can control them equally well.”
On the other hand, many tasks that require quantum computers, such as problems in physics, chemistry, or materials science, can also be expressed naturally in the qudit language. Rewriting them for quantum bits tends to make them too complex for today’s quantum computers.” Martin Rimbauer explains, “Working with something other than zero and one is very natural, not only for quantum computers but also for its applications, allowing us to unlock the true potential of quantum systems.”
