Scitech | The small things

A look at quantum nanoelectronics research at McGill

Since the early 20th century, quantum physics has sparked the interest and recruited the dedication of many, including the likes of Niels Bohr, Albert Einstein, and Richard Feynman.

Quantum physics considers physical phenomena at a microscopic level, providing a framework for understanding energy and matter at the molecular, atomic, and subatomic scale. Measuring at the quantum scale make it possible to make very precise measurements and has become crucial to the development of new technologies. Michael Hilke, a physicist at McGill, and his quantum nanoelectronics lab at McGill is looking at a number of different quantum physics applications in technology.

One such technological advancement is the quantum computer – a machine capable of computations magnitudes faster than conventional computers – which has the power to crack more complicated codes and run more complex simulations.

The chips in today’s computers – like the one you are currently using – process information in binary. This means that bits can exist in one of two states: 0 or 1. In contrast, quantum chips store information in quantum bits (qubits) that have the ability to be both 0 and 1 at the same time. What the qubit represents ‘spin state,’ which is essentially information about how an electron is spinning. These qubits are what give quantum computer chips the potential to store and process information at a rate several orders of magnitude faster than the ordinary silicon computer chip.

Quantum dot technology is one of the proposed ways that quantum computing will come to light. A quantum dot is essentially an “electron trapped in a cage of atoms.” Using light, this electron can be in an excited state (1) or ground state (0) – the same 0 and 1 that were referred to in the previous paragraph. Using this technology, one can take precise measurements of the electron’s spin, which is useful to quantum computing. One of the materials that can be used in quantum dot technology is graphene – and is one of the areas of study in the Hilke lab.

Graphene is a material with some remarkable properties. It is a crystalline form of carbon (like diamond or graphite) that is a one-atom thick. It is impermeable to gases and liquids and is the thinnest and strongest material known to date; it is also an extremely efficient conductor of electricity. Graphene’s physical properties give it the potential for many practical applications.

Up close, graphene’s carbon atoms make up a honeycomb shaped hexagon lattice. These layers of graphene can combine to form superlattices, forming symmetrical, snowflake-shaped crystals. This property of graphene means that these crystals have a larger surrounding perimeter than internal area. This enhanced surface area means that a graphene can be made more chemically efficient and reactive. Graphene’s impermeable nature make it a very good filter for small molecules when perforated with very small holes. It also has possible applications in radiofrequency detection, electricity generation, and organic displays. The Hilke lab is now is constructing single hexagonal crystals to make graphene at high qualities and for use at large scale.

The story of graphene isolation is an interesting one. It was the result of the so-called “Friday evening experiment” – tried for fun and separate from the ‘serious’ research that the lab was receiving funding for. Hilke noted that this is an exciting aspect of fundamental research – though there is a high risk of failure and a low chance of achieving good results, when they do, they can be transformational and have many important applications.

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