Can qubits with holes yield fast larger quantum computers?

A new study led by Prof Dimi Culcer (UNSW/FLEET), indicates electron holes may be the solution to operational speed/coherence trade-off, and the potential scaling up of qubits to a mini-quantum computer.

One way to make a quantum bit is to use the ‘spin’ of an electron and interaction that enables spins to talk to electric fields is called the spin-orbit interaction and is traced all the way back to Einstein’s theory of relativity. Quantum-computing researchers feared that when this interaction is strong, gains in operation speed would be offset by a loss in the ability to preserve quantum information, or coherence.

The recent study shows that the fear is unjustified, finding that electron holes, which is in effect the absence of an electron behave like positively charged electrons. The result is that quantum bits can be made robust against charge fluctuations stemming from the solid background and also that the ‘sweet spot’ at which the qubit is least sensitive to such noise is also the point at which it can be operated the fastest.

The study is expected to facilitate experimental efforts to preserve quantum information for as long as possible and enabling ‘scaling up’ quantum bits—building an ‘array’ of bits that would work as a mini-quantum computer. The paper Optimal operation points for ultrafast, highly coherent Ge hole spin-orbit qubits was published in Nature partner journal npj Quantum Information in April 2021. (DOI: 10.1038/s41534-021-00386-2)

Original source: Eureka Alert