Silicon chip enables mass-manufacture of quantum technologies


September 5, 2012

Scientists from the University of Bristol’s Centre for Quantum Photonics have developed a silicon chip that may pavé the way to the mass-manufacture of miniature quantum chips, described in open-access articles.

The leap from using glass-based circuits to silicon-based circuits is significant because fabricating quantum circuits in silicon has the major advantage of being compatible with modern microelectronics.

Ultimately this technology could be integrated with conventional microelectronic circuits, and could one day allow the development of hybrid conventional/quantum microprocessors.

Multi-mode interference coupler and the manipulation of entanglement demonstrated in a Mach-Zehnder interferometer. a) SEM image of an multi-mode interference coupler. (b) Schematic diagram of a waveguide circuit with a voltage-controlled phase shifter. (c) Illustration of the cross-section of the single-mode waveguide. (Credit: University of Bristol)

“Using silicon to manipulate light, we have made circuits over 1000 times smaller than current glass-based technologies,” said Mark Thompson, Deputy Director of the Centre for Quantum Photonics in the University’s Schools of Physics and Electrical & Electronic Engineering.

“It will be possible to mass-produce this kind of chip using standard microelectronic techniques, and the smaller size means it can be incorporated in technology and devices that would not before have been compatible with glass chips.

The Bristol-lead research team now believes that all the key components are in place to realize a fully functioning quantum processor — a powerful type of computer that uses quantum bits (qubits) and not the conventional bits used in today’s computers. This work was carried out with collaborators including Heriot-Watt University in Scotland and Delft University in the Netherlands.

Unlike conventional silicon chips that work by controlling electric current, quantum circuits manipulate single particles of light (photons) to do calculations.

These circuits exploit strange quantum mechanical effects such as superposition (the ability for a particle to be in two places at once) and entanglement (strong correlations between particles that would be nonsensical in our everyday world). The technology developed uses the same manufacturing techniques as conventional microelectronics, and could be economically scaled for mass-manufacture. These new circuits are compatible with existing optical fiber infrastructure and are ready to be deployed directly with the Internet.

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