News | November 10, 2016

A Major Breakthrough In Quantum Information Transfer Between Matter And Light

Skip stationary qubits qubit flying at speeds never reached before ... This feat achieved by a team of Polytechnique Montreal and CNRS in France us one step closer to the era where information is processed and transmitted by fully quantum principles.

Validated by imposing a peer, the article entitled "High-fidelity and ultrafast spin initialization of a hole bound to a Te isoelectronic center in ZnSe" was recently published in the prestigious journal Physical Review Letters. Creating a qubit in zinc selenide, a well-known semiconductor material, has produced an interface between quantum physics governing the behavior of the ladder in terms of nanometer and transfer of information the speed of light, thus paving the way for the manufacture of quantum communication networks.

classical vs. quantum physics physics
In today's computers, this is classical physics applies. Billions of electrons, which form electric current cooperate to form an information bit: 0, electrons are absent, and 1, electrons are present. In quantum physics, working with a single electron, which allows her to express an amazing property of nature: it can be both a 0, a 1, and the simultaneous superposition of these two states. Welcome to the qubit, the quantum equivalent of the classical bit. The qubit offers opportunities unheard researchers. Here's why.

The electron rotates on itself, a bit like a top. This is the spin. By applying a magnetic field, spin point up, down, or simultaneously up and down, to form a qubit. But there's more. Instead of using an electron, one can use his absence; it is what physicists call a "hole". Like its cousin the electron, the hole has a spin from which it can form a qubit. But whatever it is, the qubit is a quantum delicate creature. It therefore needs a favorable environment.

zinc selenide, telluride and laser: a world first
Zinc selenide, ZnSe, is a crystal where atoms are strictly ordered. It is also a semiconductor in which it is easy to introduce, deliberately, impurities, such as tellurium, a close relative of selenium in the Periodic Table, in which the holes will be imprisoned, much like bubbles air in the glass.

This environment allows the spin of the hole, our qubit, preserving its quantum information longer and faithfully; is the coherence time, time that physicists around the world are trying to extend all possible ways. That's why the choice of zinc selenide is not trivial. It offers a quiet neighborhood in the hole and, therefore, greater coherence time.

Polytechnique Montreal and CNRS in France, teamwork
Philippe St-Jean, a doctoral student in the team of Professor Sébastien Francoeur, uses photons generated by a laser to initialize the hole and store quantum information. To make reading it excites the hole and collects the emitted photons. Result: a quantum information transfer between the stationary qubit generated by the spin of the captured hole in the crystal, and the flying qubit, the photon which, of course, moves at the speed of light.

This new technique shows that it is possible to make a qubit faster than all other methods used until now. Indeed, just a hundred picoseconds or less than a billionth of a second, to spend a flying qubit to qubit stationary, and vice versa.

If this achievement bodes well for the future, much work left to do before using a quantum network to conduct banking transactions safely or build a quantum computer capable of the most complex calculations. This is the difficult task that will continue to address the research team of Sébastien Francoeur.

The Research Council Natural Sciences and Engineering Research Canada (NSERC) funded the work of Mr. Francoeur and his team.

About Polytechnique Montreal
Founded in 1873, Polytechnique Montreal is one of the largest educational and engineering research in Canada. Polytechnique ranks first in Quebec for the number of students and the scope of its research activities. With over 45,700 graduates, Polytechnique Montreal has trained nearly a quarter of the current members of the Ordre des ingénieurs du Québec. It offers more than 120 programs.Polytechnique Montreal has 250 professors and more than 8200 students. Its annual operating budget of over $ 210M, including a research budget of over 70 million.

SOURCE: Polytechnique Montreal