Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits

Australian scientists have achieved a new milestone in their approach to creating a quantum computer chip in silicon, demonstrating the ability to tune the control frequency of a qubit by engineering its atomic configuration. The work has been published in Science Advances.

A team of researchers from the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) at UNSW Sydneyhave successfully implemented an atomic engineering strategy for individually addressing closely spaced spin qubits in silicon.

The researchers built two qubits—one an engineered molecule consisting of two phosphorus atoms with a single electron, and the other a single phosphorus atom with a single electron—and placed them just 16 nanometres apart in a silicon chip.

By patterning a microwave antenna above the qubits with precision alignment, the qubits were exposed to frequencies of around 40GHz. The results showed that when changing the frequency of the signal used to control the electron spin, the single atom had a dramatically different control frequency compared to the electron spin in the molecule of two phosphorus atoms.