UNSW researchers have proposed a new way to distinguish between quantum bits that are placed only a few nanometres apart in a silicon chip, taking them a step closer to the construction of a large-scale quantum computer.
Quantum bits, or qubits, are the basic building blocks of quantum computers - ultra-powerful devices that will offer enormous advantages for solving complex problems.
Professor Michelle Simmons, leader of the research team, said a qubit based on the spin of an individual electron bound to a phosphorus atom within a silicon chip is one of the most promising systems for building a practical quantum computer, due to silicon’s widespread use in the microelectronics industry.
In a significant feat of atomic engineering, they were able to read-out the spins of individual electrons on a cluster of phosphorus atoms that had been placed precisely in silicon. They also propose a new method for distinguishing between neighbouring qubits that are only a few nanometres apart.
To make the tiny device, the researchers deposited a layer of hydrogen on a silicon wafer and used a scanning tunnelling microscope to create a pattern on the surface in an ultra-high vacuum.
This was then exposed to phosphine gas and annealed at 350 degrees so phosphorus atoms became incorporated precisely into the silicon. The device was then buried in another layer of silicon.
In a quantum computer information is stored in the spin, or magnetic orientation, of an electron. This spin can not only be in the two "classical" states – up and down – but also in a combination of both states at the same time, allowing exponentially larger amounts of information to be stored and processed in parallel.
This story is reprinted from material from UNSW, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.