Empa researchers have been awarded a significant grant that will enable them to carry out research into quantum materials.
The CarboQuant project – which will be carried out over the next ten years – is being funded by The Werner Siemens Foundation, who have contributed 15 million Swiss francs.
Developing quantum technologies
The novel research intends to lay the groundwork for new quantum technologies that could even function at room temperatures. This would be a massive advancement from existing technologies, the majority of which necessitate cooling to near absolute zero.
“With this project we are taking a big step into the unknown,” explained Oliver Gröning, project coordinator. “Thanks to the partnership with the Werner Siemens Foundation, we can now move much further away from the safe shore of existing knowledge than would be possible in our ‘normal’ day-to-day research. We feel a little like Christopher Columbus and are now looking beyond the horizon for something completely new.”
Graphene as a building material
The scientists are advancing previous research efforts; in 2010, they succeeded in synthetising graphene strips – nanoribbons – from smaller precursor molecules for the first time. With their unique synthesis approach, the Empa team can now build carbon nanomaterials with atomic precision, thus accurately identifying their quantum properties.
Graphene is highly regarded as a potential building material for computers of the future. The novel material is just one atomic layer thin, and promises faster and more powerful computer architectures than the semiconductor materials currently used.
Magnetic carbon
In 2017, the research team, alongside colleagues from the University of California, Berkeley, established the first transistor from graphene nanoribbons and published the result in Nature Communications.
The researchers then discovered that the carbon nanomaterials displayed properties of magnetism. Through this, the team was able to demonstrate spin fractionalisation. This fractionalisation only occurs when many spins – fundamental quantum magnets – can be brought into a common, coherent quantum superposition. The Empa researchers have now achieved this phenomenon in their precisely synthesised molecular chains.
CarboQuant is intended to build on these special spin effects in graphene nanoribbons. Gröning added, “So far, we see spin states at very specific locations in the nanoribbons, which we can generate and detect. The next step will be to manipulate these spin states deliberately, for example, to reverse the spin at one end of the nanoribbon and thus elicit a corresponding reaction at the other end.”
This would give Empa researchers something unique to work with; a quantum effect that is stable and can be manipulated even at room temperature or requiring just moderate cooling.
Towards quantum devices
“If we manage to control the spin states in our nanoribbons, we can use them for quantum electronic devices, commented Gröning.
While one part of the team continues to study spin effects in a high vacuum, other team members will focus on the everyday suitability of the graphene nanoribbons.
“We have to get the components out of the protected environment of the high vacuum and prepare them in such a way that even in ambient air and at room temperature, they do not disintegrate. Only then can we equip the nanoribbons with contacts – which is the prerequisite for practical applications without the need of an elaborate infrastructure,” said Gröning.
Going forward
The researchers still have a long way to go until this technology is realised. Already the initial phase; the control and time-resolved measurement of spin states, demands an entirely new set of equipment that the researchers will have to develop and build.
“We need to combine the scanning tunnelling microscope (STM), in which we synthesise the nanoribbons and look at their structure, with ultra-fast measurements of their electronic and magnetic properties,” Gröning explained. That can be done by high-frequency electrical signals at high magnetic fields and by irradiation with very short, extremely intense laser pulses.
To accomplish this, two new measurement systems are being set up at Empa, which will also play a crucial part in the team’s other research projects, and which are co-funded by the Swiss National Science Foundation (SNSF) and the European Research Council (ERC).
“This shows that synergies always emerge from different projects,” added Gröning. “But also that ambitious goals can only be achieved with the support of different players at multiple levels.”
The team has projected that it will take two to three years just to set up these new analytical instruments and to carry out the first test runs.
The team at Empa’s nanotech@surfaces lab now have long-term creative freedom on the way to their bold aim: a possible building material for next-generation quantum computers. “We don’t yet see the island that might be out there. But we can guess it, and if there is something out there, we are confident that we will find it, thanks to the support of the Werner Siemens Foundation and our national and international research partners,” concluded Gröning.
