Scientists Successfully Record Electron’s Quantum Behavior Using Laser Light

Researchers have developed a technique to record and control an individual electron’s behavior at the quantum mechanical level. The discovery could bring information processing and quantum computing a step closer. A research team headed by the University of Chicago scientists used ultrafast pulses of laser light to control an electron’s quantum state and observe changes in that individual electron’s state over time.

Nitrogen-vacancy center is a defect found naturally occurring in diamonds

The electrons were contained inside nanoscale defects in a diamond. Scientists focused on the electron’s quantum mechanical property, called spin. The conventional computers hold bits of data in the form of binary 0 and 1. Similarly, the quantum-based computer spin states of a charged electron represent a quantum bit, known as qubit. Findings of the study appeared in the journal Science.

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At the center of the study was a quantum spin system called nitrogen-vacancy center. It’s an atomic-scale defect naturally occurring in diamonds. In the nitrogen-vacancy center, there is a single nitrogen atom sitting adjacent to an empty point in the diamond’s crystalline latticework. Such defects have aroused scientists’ curiosity for more than a decade, said senior researcher and lead author of the study David Awschalom.

Time period between the two pulses critical to the electron’s interactions

Researchers were able to use laser light to fully control the quantum state of this defect. They successfully illuminated a single such nitrogen-vacancy center with two exceptionally short pulses of laser light. Each pulse lasted “less than a millionth of a millionth of a second.” The first pulse excited the quantum state of the electron in the nitrogen-vacancy center defect, which then switches states in a characteristic way. The second pulse stops that process and captures an image of the quantum state.

The time period between the two pulses is extremely critical because that timescale determines how the electron interacts with its surroundings, said researchers. They tested the electron’s reaction to a large number of different pulse timescales by progressively extending the elapsed time between the two pulses. It allowed them to create a representation of the quantum dynamics of an electron in the NV center.

Scientists not involved in the study said the discovery is an important milestone on the road to quantum computing.