Researchers Use Photovoltage Measurements to Observe Quantum Spin Effects

Scientists have observed specific spin phenomena in topological insulators and metals using a scanning photovoltage microscope. This new approach to examining quantum behavior of materials could yield information useful for building future quantum computing applications.

Researchers from the National University of Singapore (NUS) imaged spin accumulations in topological insulators Bi2Se3 and BiSbTeSe2 and in a heavy metal platinum. An applied electrical current was used to influence the electron spin at the quantum level for all of these materials; and the scientists were able to directly visualize this change using polarized light from the microscope. Experiments were performed at room temperature, making the approach a practical method of visualization that could be applicable to other materials.

"The NUS team, together with our collaborators from Rutgers, The State University of New Jersey in the United States and RMIT University in Australia, showed a practical way to observe and examine the quantum effects of electrons in topological insulators and heavy metals which could later pave the way for the development of advanced quantum computing components and devices," said professor Yang.

Researchers believe that their work could lead to a way to optically detect the accumulated spins in various metallic and semiconducting materials. By helping to extract spin-related parameters, the work could advance understanding of the interactions between spins and light in various materials systems.

Researcher Liu Yang said, “Our method can be used as a powerful and universal tool to detect the spin accumulations in various materials systems. This means that developing better devices for quantum computers will become easier now that these phenomena can be directly observed in this way.”

The team is planning to test its new method on other materials with spin properties. It hopes to work with industry partners to further explore the various applications of its novel technique, with a focus on developing devices that will be used in future quantum computers.

Quantum computers use laser light to interact with electrons in materials to measure the phenomenon of electron “spin.” Many spin states can exist simultaneously, allowing for more complex computing.

The research was published in Nature Communications (doi: 10.1038/s41467-018-04939-6).