Researchers from University Of New South Wales (UNSW) have created artificial atoms in silicon chips that offer improved stability of qubits.
They created artificial atoms in a silicon quantum dot, a tiny space in a quantum circuit where electrons are used as qubits. An artificial atom has no nucleus, but it still has shells of electrons whizzing around the center of the device, rather than around the atom’s nucleus.
Artificial atoms with a higher number of electrons turn out to be much more robust qubits than previously thought possible, meaning they can be reliably used for calculations in quantum computers. This is significant because qubits based on just one electron can be very unreliable.
The team demonstrated an electrostatically confined quantum dot that reveals a well defined shell structure. They observed four shells (31 electrons) with multiplicities given by spin and valley degrees of freedom. Various fillings containing a single valence electron—namely 1, 5, 13 and 25 electrons—were found to be potential qubits. An integrated micromagnet allowed them to perform electrically-driven spin resonance (EDSR), leading to faster Rabi rotations and higher fidelity single qubit gates at higher shell states. They investigated the impact of orbital excitations on single qubits as a function of the dot deformation and exploit it for faster qubit control.
In a continuation of this latest breakthrough, the group will explore how the rules of chemical bonding apply to these new artificial atoms, to create artificial molecules. These will be used to create improved multi-qubit logic gates needed for the realization of a large-scale silicon quantum computer.
The paper has been published in Nature Communications. (SciTechDaily)
