Scheme: University Research Fellowship
Organisation: University of St Andrews
Dates: Oct 2011-Sep 2014
Summary: Building materials that are capable of efficiently absorbing light is an important goal in current research, since these form a key part of several different technological applications. For example, in a solar cell device light must be absorbed first, and converted to electronic energy, before it can be used as a power source. Further, sensitive light detectors are important for all kinds of applications, ranging from astronomical observations, to building cameras that will work in low light levels.
My research is about quantum systems and how their remarkable properties can be engineered to enhance current technology, or to build new completely new kinds of technology. In the last year, I have been thinking about the problem of light absorption. My group and I have come up with a way of harnessing quantum mechanics that can lead to much higher probability of light being absorbed in a device than you would expect from classical physics.
The system I’m looking is a molecule consisting of a number N of chromophores, or light absorbing units. Intuitively, you would expect that the rate of absorption from the N units would simply be N times that of what each unit could absorb individually. We have found, however, that this intuition is wrong: by arranging the chromophores in a particular pattern, it is possible to make them absorb light at N squared times the individual rate. This can be a very significant enhancement - for example, if you have ten absorbers, then by harnessing quantum mechanics you would get ten times more light absorbed than is possible in a conventional system.
We hope now that our ideas can be tested in the lab, to prove that the principle of ‘superabsorption’ can work. In future we could use this effect for better solar cells, or even wireless power transmission.
Organisation: Heriot-Watt University
Dates: Oct 2006-Sep 2011
Summary: Quantum mechanics describes the behaviour of the ‘nanoworld’ of the atoms and molecules that form the building blocks of all the materials we see around us. These basic units can behave quite differently to the larger objects that they make up. To see this, imagine an experiment that measures a property of an atom - its energy say. Even if we carefully prepare the atom in a particular state, we can’t always predict the results of the energy measurement. In fact, we could get several different values, each with a certain probability.
My work is about how to use this uncertainly to our advantage in a new kind of computer. At first this may seem absurd: how can uncertainty be useful when performing a precise algorithm? The answer lies in another quantum property – interference - which means that we can combine the various probabilities in a group of atoms to make the answer appear from the vast number of possible outcomes. Since such a lot of information can be simultaneously stored in such a ‘quantum computer’, there exist algorithms that outperform conventional processors on a vast scale. For example, quantum programs could revolutionize cryptography and sensing - and they could have a huge impact on our understanding of quantum systems themselves. Building such a quantum computer is not easy: quantum states are very fragile, and their tiny extent means they are very hard to control and measure them individually. My work looks at finding ways to overcome these challenges. For example, this year I have shown how the state of a single electron can be amplified to many electrons. This has been done before, but my idea shows that the amplifying system can be very simple indeed: a completely uniform grid of electrons that might be found in many different solid state materials. The control needed is also trivial - a simple microwave source will do it. A fascinating feature of this work is that it relied on a result from the theory of numbers, a abstract branch of maths.