Quantum Effects in Electronic Nanodevices (QuEEN)

Put your hand under a working laptop computer and you'll find that it's warm, due to the heat produced by the transistors in it. This isn't just a problem for your own computer: nearly 5% of the world's electricity is used by computers and the internet, a figure expected to double over the next decade. Much of this is wasted in generating heat that, according to thermodynamic theory, is not needed for information processing; and over half is for cooling systems to remove the unwanted heat. The resulting carbon emissions are comparable to the total global aviation industry.

If we can reduce the energy consumption of logic operations in information technologies, or scavenge just a fraction of the waste heat, the effect on energy use and carbon emissions could be vast. Recent research breakthroughs have opened up new possibilities for making tiny electronic components and circuits, based on individual molecules, which have the potential to do just that (since their behaviour is not constrained by the laws of classical physics). To make this a reality, we must first learn to understand and control quantum effects in electronic nanodevices.

We can use a new material, graphene, to make mechanically and chemically stable electrodes and connect them to electrically-active molecules. New methods allow us to make a very small gap in graphene which is just the right size for a molecule or a single strand of DNA (for fast and cheap DNA sequencing). Chemical units have been developed that attach to molecules and adhere like sticky notes to the graphene contacts on each side of the gap.. With graphene electrodes we can also make magnetic connections to single molecules to create molecular memory devices. A phenomenon called quantum interference can dramatically affect the flow of electric current in molecules. Harnessing these quantum effects will enable us to make tiny switches that would consume very little energy, and to generate electricity from small differences in temperature. The time is ripe for a focused research effort, drawing together these advances to transform our understanding and to pave the way for practical applications.

Our programme is one of discovery science with a view to practical benefit. QuEEN will first establish the basic platform technology for experiments on single-molecule devices, including selection of the best molecules and control of their quantum interference by a local electric field. It will conclude by seeking to transfer results from rather ideal (cryogenic) laboratory conditions to a real-world environment, at room temperature. In between those two challenges, we shall explore three particularly promising areas for scientific discovery and application: controlling the magnetic property of an electron, known as spin, for quantum interference for potential use in universal computer memories; seeing how much electricity a molecule can generate if its ends are held at different temperatures, offering the potential for energy harvesting; and finding the performance limits of a single-molecule transistor, for potential uses in low-power computing and timer-controllers for the Internet of Things.

The research requires four core skill sets, which form a virtuous circle: chemistry, to design and synthesise the molecules at the heart of our devices and stick them reliably to electrodes; nanofabrication, to make molecule-sized gaps in graphene ribbons; measurement techniques and advanced instrumentation to control the environment and characterise the quantum effects; and theory, to predict the effects, screen potential molecules, and interpret the results. QuEEN brings together a research team with exactly the right mix of expertise; an Advisory Board with wide experience of successful technological entrepreneurship; and a group of industrial partners who will not only shape and assist with the research but also provide a pathway to technological innovation and real-world applications.

If we can (a) harness quantum interference, and other effects, in graphene-based single-molecule devices; and (b) demonstrate the practical and commercial viability of such devices (in terms of performance and reproducibility) compared to existing technologies, then that could pave the way for major long-term economic and societal benefits.

Ultimately, ultra-low power transistors and/or thermo-electric energy recovery methods (enabling the design of high-performance thin-film materials which convert waste heat to electricity) could significantly reduce electricity consumption in ICT. This would not only reduce running costs for end users around the world, and for customers of data-intensive services, but also contribute to the wider goal of low-carbon economies. Reduced power consumption in sensors, which has the effect of extending usable battery lifetimes, will also be an important enabler for the Internet of Things.

Our work on harnessing magnetic properties could lay the foundations for new 'universal' computer memory technologies, which would further reduce power consumption and increase speed and efficiency (by removing the existing requirement for separate memories for computation and for storage).

These disruptive technologies would open up major new commercial opportunities for electronics and ICT component manufacturers, including next-generation products to replace current technologies, alongside entirely new markets and products. They would stimulate job creation and the establishment of new companies, and promote inward R&D investment into the UK by major multi-national companies.

These are all long-term outcomes that will require further translational research by physicists, engineers and computer scientists to build on our results - addressing issues such as manufacturability, scale-up, and integration - and take our devices from laboratory proof-of-concept to real-world application.

In the nearer term, the QuEEN programme will deliver economic and commercial benefits in at least two ways:

- our patented graphene nanogaps show significant promise as a route to enhanced DNA sequencing technologies; collaborative work with a commercial project partner will seek to exploit this;

- the sensitive, low-noise electronic measurement systems we will develop will be of interest to cryogenic instrument manufacturers, and could lead to new or improved products.

Throughout the programme, we shall work with our experienced Advisory Board, our Project Partners and the UK National Quantum Technologies Hub network to identify other (niche) opportunities for near-term application and impact.