Announcements - Break Through in Quantum Computing – Highlighted in Nature Physics

November 27, 2011 — Ottawa, Ontario

Revolutionary work on quantum computing conducted by the National Research Council of Canada is laying the foundation to create the first scalable quantum computer.  The findings have been published in the highly esteemed journal Nature Physics.

These days, electronic gadgets are almost obsolete as soon as they leave the store shelves.  The new model is always faster with more functionality. This is made possible, by the remarkable exponential evolution of integrated circuits involving individual components that are made smaller and smaller with each computer chip generation. This is sometimes referred to as “Moore’s Law”. At some point, all good things must come to an end and indeed further scaling down of processors is rapidly and unavoidably coming to an end. Industry is currently seeking a new paradigm which will require doing things smarter.

Quantum computation, using the amazing power of quantum mechanics, may prove to be the solution. A quantum computer could not only solve many important problems that are simply too hard for classical computers, it could break classical encryption schemes. Such technology would lead to our ability to understand complex chemical and biological processes - and thus lead to the development of new drugs and materials. While there are many ideas of how to potentially realize a quantum computer, NRC researchers are planning to take advantage of the technology and tools developed by the semiconductor industry over the past few decades.  The research team is currently developing small semiconductor quantum circuits, and beginning to scale them up in the same way that classical integrated circuits originally started as single large transistors sixty years ago.   A few years ago NRC scientists showed for the first time that one could use such circuits to isolate individual electron spins from a layer that contained 100,000,000,000 electrons every square centimetre. The single spins would become the quantum bits of the new computer. Today, these scientists have gone one giant leap further. In the Nature Physics article they demonstrated for the first time the ability to coherently manipulate complex quantum states based on three interacting electron spins in the most complex semiconductor spin qubit circuit developed to date. Whereas quantum logic operations, the equivalent of adding and subtracting etc…, can be performed with individual and pairs of spins, the need for the more complex coherent three spin states has long been established theoretically. Encoding information into such states can increase the coherence time of spins, the useful time for performing quantum operations. They will also be necessary for quantum error correction schemes which are required to make sure that unavoidable errors are constantly corrected. Three-spin states have also been proposed as the basis of a novel almost magical quantum bus which would transport spins rapidly between locations of a quantum circuit without ever appearing in places in between.

NRC was uniquely equipped to make such a major advance since it houses all the necessary technologies. The advanced material was grown by the epitaxy group; the group contains the only facility capable of growing such high quality material in Canada. The state of the art device was developed and fabricated within NRC’s nanofabrication facility. The devices were measured in the advanced measurement and characterization laboratories of the quantum physics group within the NRC quantum information center. They were supported by sophisticated analysis and modelling from the NRC quantum theory group.