Quantum research breaks through major boundary

The field of quantum computing took a major leap this week, thanks to researchers from the University of NSW (UNSW).

The team of scientists developed a two-qubit gate between atom qubits in silicon.

Two-qubit gates are the foundations of any quantum computer. This version is the fastest that’s ever been achieved in silicon, completing an operation in 0.8 nanoseconds.

A two-qubit gate is an operation between two electron spins. The UNSW team was able to place two atom qubits closer together than ever before, while observing and measuring their spin states.

Previously, the precision needed to construct not only the atom qubits but the associated circuity to initialise, control and read-out the qubits at the nanoscale was thought to be impossible.

“Using our unique fabrication technologies, we have already demonstrated the ability to read and initialise single electron spins on atom qubits in silicon with very high accuracy. We’ve also demonstrated that our atomic-scale circuitry has the lowest electrical noise of any system yet devised to connect to a semiconductor qubit,” said professor Michelle Simmons.

The next step for the research will be to manufacture a 10-qubit quantum integrated circuit, which UNSW hopes can occur in three to four years.

The team used a scanning tunnelling microscope to capture phosphorus atoms in silicon.

Then, the researchers measured how the qubit states evolved, and were able to show how to control the interaction strength between two electronics on the nano-second timetable.

“Importantly, we were able to bring the qubit’s electrons closer or further apart, effectively turning on and off the interaction between them, a prerequisite for a quantum gate,” said Yu He, lead co-author.

What this study demonstrates, on a greater level, is that nature can be controlled at its very smallest level.

“We can create interactions between two atoms but also individually talk to each one without disturbing the other,” said Simmons.

Quantum computing promises the potential to radically speed up the time that large amounts of data can be processed. It could reduce computing time from centuries to hours or minutes.

There is the potential for use in machine learning, scheduling and logistical planning, rapid drug design and testing and medical uses.