Researchers at the National Institute of Standards and Technology and the National Renewal Energy Laboratory have reported a way to measure accurately the amount of laser light needed to shift the electrons in a particular type of quantum dot between two discrete states. This advance is another step toward the use of quantum dots as the “ones and zeros” for a superfast quantum computer.

The new technique measures the dipole moment (the strength of the interaction between quantum dots and electromagnetic waves) directly by enclosing the dots in a cavity where a pulse of laser light can pass over them repeatedly. With each successive pass, the laser light gets a little dimmer as the dots absorb some of the energy. Averaging the changes in energy over many pulses gives an accurate measurement of the dipole moment.

The ability to measure accurately the dipole moment for quantum dots made of different materials should help nanotechnology researchers optimize these structures for a variety of applications, including quantum computing and quantum communications.

Press release