Room-temperature qubit breakthrough for quantum computing

Material made from the ashes of mothball ingredient naphthalene shows quantum potential.

We are one step closer to a true quantum computer following a breakthrough which researchers say will allow qubits to be used at room-temperature.

One of the practical challenges of quantum computing has been the requirement to cool the quantum bits (qubits) to incredibly low temperatures, close to absolute zero and comparable to the temperature of space.

This super-cooling is necessary so that the quantum states of the qubit’s components remain ‘coherent’ and can perform computations.

University of Sydney’s Dr Mohammad Choucair, together with a team of researchers from Switzerland and Germany, has made a conducting carbon material and demonstrated its potential to perform quantum computing at real-world temperatures. It can also integrate into silicon, the chosen material of Sydney’s Centre for Quantum Computation and Communication Technology (CQC2T) own bid to build a quantum computer.

Carbon nanosphere

SEM, Scanning electron microscope images, of the CNSs, Carbon nanospheres. (a) and (b) of the CNSs at low magnification, and (c) and (d) at higher magnification, with (c) being from a region in (b). Scale barsrepresent in (a) 5 µm, (b) 1 µm, (c) 200 nm, and (d) 200 nm. SEM images show an extensive formation of carbon nanoparticles spanning micron scales.

Nature Communications – Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres

The material is made of the ashes from burning naphthalene, a chemical commonly found in moth balls.

“We have made quantum computing more accessible,” said Choucair. “This work demonstrates the simple ad-hoc preparation of carbon-based quantum bits.

“Chemistry gives us the power to create nanomaterials on-demand that could form the basis of technologies like quantum computers and spintronics, combining to make more efficient and powerful machines.”

Choucair’s paper, Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres, was published online on Nature Communications this evening.

He said he believed the discovery would help bring forward ‘practical quantum computing’ to ‘within a few years’.


The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin–lattice and spin–spin relaxation times of electrons. Minimizing the effects of spin–orbit coupling and the local magnetic contributions of neighbouring atoms on spin–lattice and spin–spin relaxation times at room temperature remain substantial challenges to practical spintronics. Here we report conduction electron spin–lattice and spin–spin relaxation times of 175 ns at 300 K in 37±7 nm carbon spheres, which is remarkably long for any conducting solid-state material of comparable size. Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state. These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature

15 pages of supplemental material

SOURCES- Australia CIO, Nature Communications