Scientists at Virginia Commonwealth University (VCU) have developed a technique that uses extremely small magnets to better control the basic units of quantum computers. The study, published in Nature Communications, explores spin-based quantum computing. In this type of system, information is held in the spin of electrons.
Quantum computers use qubits. A qubit in this research starts as a tiny diamond with a special defect. Scientists remove two side-by-side carbon atoms from the diamond lattice. They replace one missing spot with a nitrogen atom and leave the other empty. This leaves unpaired electrons that act as the qubit. By setting their spin up or down, the system can represent and process quantum information.
Controlling the spin accurately across many qubits has been difficult. Most past work used electromagnetic signals that cover a wide area and can disturb the spins of electrons in neighboring qubits. Because of this interference, qubits cannot be packed closely on a chip.
A new control method with nanomagnets
The VCU scientists addressed the issue by creating nanomagnets roughly 200 nanometers in size. They paired each nanomagnet with a diamond qubit. Instead of broad electromagnetic signals, they applied acoustic waves, vibrations similar to sound, to move the nanomagnet. The moving magnet then locally changes the magnetic field felt by the electrons in the diamond. Experiments confirmed that this changed the quantum state of the electrons as intended.
This localized control could let researchers place qubits much closer together. The approach may also consume less power, keep information stable longer, and allow operation at higher temperatures. Such improvements matter because energy use and reliability become critical when scaling to large numbers of qubits. The technique might additionally enable extremely precise sensing for studying chemical reactions or biological processes at a fundamental level.
Despite these advances, constructing a full quantum computer with many interconnected qubits is still an ongoing effort. The work provides one piece of the hardware puzzle but does not yet solve all challenges in the field.