University of Queensland scientists have built and tested quantum logic gates that are vastly more powerful than those that have gone before by exploiting the higher dimensions available in quantum mechanics.

For example, a qubit can be encoded in a photon’s polarization. But a photon has other dimensions which can also be used to carry information, such as its arrival time, photon number or frequency. By exploiting these, a photon can easily be used as a much more powerful three level system called a qutrit.

That allows a dramatic reduction in the number of gates necessary to perform a specific task. Using only three of the higher-dimension logic gates, the team has built and tested a Toffoli logic gate that could only have been constructed using 6 conventional logic gates. And they say that a computer made up of 50 conventional quantum logic gates could be built using only 9 of theirs.