Scientists develop new technique for measuring the state qubits in quantum computing

New technique could enable quantum computers to scale-up to millions of qubits

Researchers at Syracuse University have developed a new technique for measuring the state of quantum bits, or qubits, in a quantum computer.

Working with collaborators at the University of Wisconsin, the researchers go by the name of the Plourde Group and were led by Britton Plourde, professor of physics in Syracuse's College of Arts and Sciences.

The group specialises in the fabrication of superconducting devices and their measurement at low temperatures.

Qubits follow the laws of quantum mechanics. These laws enable qubits to exist in superpositions of their two states (zero and one), in contrast to digital bits in conventional computers that exist in a single state.

In a recent study, Plourde said that superposition, when combined with entanglement or "another counterintuitive aspect of quantum mechanics", leads to the possibility of quantum algorithms with myriad applications.

"These algorithms can tackle certain problems that are impossible to solve on today's most powerful supercomputers," he said. "Potential areas impacted by quantum information processing include pharmaceutical development, materials science and cryptography."

While industrial-scale efforts by teams at technology giants such as Google and IBM have recently led to quantum processors with more than 50 qubits. Earlier this year, Google revealed an experimental 72-cubit quantum processor.

These qubits consist of superconducting microwave circuits cooled to temperatures near absolute zero.

However, building a quantum computer powerful enough to tackle major calculations will require at least several hundreds of qubits, or even more, said Plourde.

The current approach to measuring qubits involves low-noise cryogenic amplifiers and substantial room-temperature microwave hardware and electronics, all of which are difficult to scale up to significantly larger qubit arrays. However, the researchers claim to have uncovered a different way of doing this.

"We focused on detecting microwave photons," said Plourde. "Our approach replaces the need for a cryogenic amplifier, and could be extended, in a straightforward way, toward eliminating much of the required room-temperature hardware, as well."

Plourde added that the technique could eventually enable quantum processors to scale to millions of qubits.

In January this year, the group also revealed more information about some of the tools it is developing to support the creation of quantum computers.