Researchers from the University of Rochester outlined a new method to control electron spin in silicon quantum dots that we can use to manipulate data in a quantum system. They published their findings in a paper in Nature Physics. The research could pave the way for a practical silicon-based quantum computer.
Scientists have long considered controlling the spin of electrons in quantum dots to manipulate the transfer of quantum information. Each electron in a quantum dot has intrinsic magnetism. Scientists call this “electron spin” since each electron is a negatively charged particle that behaves as though it were rapidly spinning, and the spin gives rise to magnetism.
Electron spin offers long coherence times and high gate fidelities and is compatible with advanced semiconductor manufacturing techniques. A major challenge, however, is controlling electron spin.
Electron spin resonance (ESR) involves applying oscillating radio frequency magnetic fields to the qubits and typically controls spin. However, it also has several limitations, including generating and precisely managing the oscillating magnetic fields in cryogenic environments.
The researchers outlined a new method for controlling electron spin in silicon quantum dots that do not rely on oscillating electromagnetic fields but is based on “spin-valley coupling,” which happens when electrons in silicon quantum dots transition between different spin and valley states. While the spin state of an electron refers to its magnetic properties, the valley state refers to a different property related to the electron’s spatial profile.
The researchers apply a voltage pulse to harness the spin-valley coupling effect and manipulate the spin and valley states, thereby controlling the electron spin.