Defects promise quantum communication through standard optical fiber

ScienceDaily | 10/1/2018 | Staff
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By using phenomena like superposition and entanglement, quantum computing and quantum communication promise superior computing powers and unbreakable cryptography. Several successes in transmitting these quantum phenomena through optical fibers have been reported, but this is typically at wavelengths that are incompatible with the standard fibers currently used in worldwide data transmission.

Physicists from the University of Groningen in the Netherlands together with colleagues from Linköping University and semiconductor company Norstel AB, both in Sweden, have now published the construction of a qubit that transmits information on its status at a wavelength of 1,100 nanometers. Furthermore, the mechanism involved can likely be tuned to wavelengths near those used in data transmission (around 1,300 or 1,500 nanometers).

Work - Defects - Silicon - Carbon - Crystals

The work started with defects in silicon carbon crystals, explains PhD student Tom Bosma, first author of the paper. 'Silicon carbide is a semiconductor, and much work has been done to prevent impurities that affect the properties of the crystals. As a result, there is a huge library of impurities and their impact on the crystal.' But these impurities are exactly what Bosma and his colleagues need: they can form what are known as color centers, and these respond to light of specific wavelengths.

When lasers are used to shine light at the right energy onto these color centers, electrons in the outer shell of the molybdenum atoms in the silicon carbide crystals are kicked to a higher energy level. When they return to the ground state, they emit their excess energy as a photon. 'For molybdenum impurities, these will be infrared photons, with wavelengths near the ones used in data communication', explains Bosma.

Material - Point - Qubits

This material was the starting point for constructing qubits, says...
(Excerpt) Read more at: ScienceDaily
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