A research team led by David Awschalom at the University of California, Santa Barbara has revealed that crystal defects present in silicon carbide, a commonly utilized semiconductor material used for electronics applications, can be manipulated at the quantum mechanical level, paving the way to use quantum physics for nanoscale sensing and ultrafast computing applications.
David Awschalom. Credit: Rod Rolle
Crystal imperfections are unwanted in traditional semiconductor-based electronics, as they trap electrons at a specific crystal site. However, the research team found that the trapping of electrons by certain defects in silicon carbide initializes their quantum states, which can be accurately controlled and gauged utilizing microwave and light radiation. Hence, the imperfections can be used as a quantum bit or qubit, the fundamental unit of a quantum computer and a transistor’s quantum mechanical analog.
Awschalom commented that many crystal defects do not have these properties, as they are closely connected to a defect’s atomic structure and its semiconductor host’s electronic behavior. The nitrogen-vacancy center, a defect in diamond, demonstrates the same characteristics and can be used as qubits at room temperature. However, it is challenging to develop diamond and use it for the production of integrated circuits. On the contrary, superior quality silicon carbide crystals in different sizes are manufactured for commercial applications.
During the study on crystal defects utilizing infrared light for a broad array of temperatures, the research team discovered that two defect types can be used as qubits at room temperature similar to the diamond nitrogen-vacancy center. According to the team, the defects and these features of silicon carbide make it suitable for applications aimed at coupling quantum mechanical objects and advanced optical and electronic circuitry.