Quantum behavior is a strange, fragile thing that hovers on the edge of reality, between a world of possibility and a Universe of absolutes. In that mathematical haze lies the potential of quantum computing; the promise of devices that could quickly solve algorithms that would take classic computers too long to process.
For now, quantum computers are confined to cool rooms close to absolute zero (-273 degrees Celsius) where particles are less likely to tumble out of their critical quantum states.
Breaking through this temperature barrier to develop materials that still exhibit quantum properties at room temperatures has long been the goal of quantum computing. Though the low temperatures help keep the particle’s properties from collapsing out of their useful fog of possibility, the bulk and expense of the equipment limits their potential and ability to be scaled up for general use.
In one latest attempt, a team of researchers from the University of Texas, El Paso has developed a highly magnetic quantum computing material that retains its magnetism at room temperature – and doesn’t contain any high-demand rare earth minerals.
“I was really doubting its magnetism, but our results show clearly superparamagnetic behavior,” says Ahmed El-Gendy, senior author and physicist at the University of Texas, El Paso.
Superparamagnetism is a controllable form of magnetism whereby applying an external magnetic field aligns the magnetic moments of a material, and magnetizes it.
Molecular magnets, like the material developed by El-Gendy and colleagues, have returned to the fore as one option for creating qubits, the basic unit of quantum information.
Magnets are already used in our current computers, and they have been at the helm of spintronics, devices that use an electron’s spin direction in addition to its electronic charge to encode data.
Quantum computers could be next, with magnetic materials giving rise to spin qubits: pairs of particles such as electrons whose directional spins are linked, albeit momentarily, on a quantum level.
Conscious of the demand for rare earth minerals used in batteries, El-Gendy and colleagues experimented instead with a mixture of materials known aminoferrocene and graphene.
Only when the researchers synthesized the material in a sequence of steps, rather than adding all the composite ingredients at once, did the material exhibit its magnetism at room temperature.
The sequential synthesis method sandwiched the aminoferrocene between two sheets of graphene oxide, and produced a material 100 times more magnetic than pure iron. Further experiments confirmed the material retained its magnetic properties at and above room temperature.
“These findings open routes of room temperature long-range order molecular magnets and their potential for quantum computing and data storage applications,” El-Gendy and colleagues write in their published paper.
More tests of this new material will of course be required, to see if the results can be replicated by other groups. But progress in this field of molecular magnets is encouraging and offers another promising option of creating stable qubits.
In 2019, Eugenio Coronado, a materials scientist at the University of Valencia in Spain, wrote: “The milestones reached in the design of molecular spin qubits with long quantum coherence times and in the implementation of quantum operations have raised expectations for the use of molecular spin qubits in quantum computation.”
More recently, in 2021, researchers developed an ultra-thin magnetic material just one atom thick. Not only could its magnetic intensity be fine-tuned for the purposes of quantum computing, but it also works at room temperature.
The study has been published in Applied Physics Letters.