Qubit system promises efficiency

Canada Excellence research chair and University of Waterloo chemistry professor David Cory discussed his vision for a 100 qubit quantum computer Jan. 23 during the first instalment of the UW “Research Talks” lecture series.

A qubit is a system in quantum mechanics that can be used in contrast to the standard bit system used in everyday computers for information storage. 

While bits are only able to exist in one state at a time, qubits are able to exist in two states simultaneously, allowing for increased efficiency and storage. 

At this moment, a standard Macbook using the bit system runs at an operating efficiency equivalent to 20 qubits. The maximum amount of qubits achieved in a computer system thus far has been 13, but Cory believes that the tools needed to create an extremely effective computer with almost eight times the number of qubits currently exist.

“There are things we can do in the quantum world that cannot be done in the classical world,” Cory said during the talk. “If we can build a device that is uniquely quantum mechanical, then we’ve reached the ultimate efficiency that nature allows.”

According to Cory, one of the main challenges of creating a quantum computer is that the storage and transfer of information must solely rely on quantum mechanics and be completely isolated from the rest of the world.

To achieve isolation, the model computer will use the spinning properties of various parts of an atom, such as the nucleus and the electron.

The model computer will have three main components: nuclear spin, electron spin, and a superconducting circuit.

Nuclear spins have an extremely small magnetic moment, so they are hard for the environment to detect and can hold quantum information for minutes. Electron spins transfer this information rapidly, and the superconducting circuit helps reset the spins such that information can be continuously transferred.

Using this knowledge, quantum information can be isolated and stored from the classical world, but still transferred quickly.

Cory currently works with a group of undergraduate, graduate, and post-doctoral students, as well as staff in the Quantum NanoFab facility, on this project. 

“The Institute for Quantum Computing brings together disciplines that connect us right across the university so that we have colleagues in all the departments of engineering, math, and science,” noted Cory. “It’s great fun to be here because we can share knowledge and capabilities and bring that to work on a common problem.”