Willing waves as you wish
When you hear the word ‘wave’, most people think of surfing or an elaborate hair style. Arguably more important to human life are however light and sound waves that support our two primary senses.
Light and sound waves are being put to good use in our Graduate School.
Incredibly fast: you struggle with your eyes to see movement in 100 milliseconds; how about trying to distinguish 10-15 s! This is being done and we have on different occasions achieved the world’s shortest visible light pulses.
Just like an expensive camera that can freeze high speed motions, our 10-15 second camera can capture molecules in motion or whizzing electrons in atoms.
Incredibly high pitch: with your ears you can distinguish sounds up to 20000 cycles/second (Hz). Bats can hear up to 100000 Hz. We are using sound pulses up to 1000000000000 Hz! (1012 Hz) to look into tiny structures with micron or nanometer (10-6-10-9 m) dimensions. These micro- or nano-structures are used in everything from electronics to cellphones.
We also use these sound pulses to watch tiny ripples travelling on crystals, just like water waves travel over the sea, but a million times smaller.
Incredibly far: using light that has travelled across the cosmos we are searching for new extrasolar planets with long baseline interferometry. In this way we eliminate the light from the host star to home in on the planet itself.
How weird is your shape?
Topology is a field of study in which a doughnut is equal to a tea cup! You see they both have only one hole in them. If you imagine they are made of wet clay then you can deform one into the other. Topology originated as a branch of mathematics and has played an important role in the development of physical theories, for example in Einstein’s general theory of relativity.
We use Topology at our Graduate School to understand materials, networks, economics, and computers from a broader perspective.
Weird crystals: a Möbius strip can be made by turning a strip of paper by 180 degrees before sticking the ends together. Who would have believed that a crystal could form in this shape? This was achieved for the first time in our Graduate School.
Now we are now measuring the properties of such crystals to find new uses for them.
Optical and acoustic vortices: everyone knows that water will form a whirlpool when it goes down the plug hole. What about whirlpools of light or sound? We are busy visualizing them. The centre of the whirlpool is a special point that is called a singularity. Water, sound and light can show these.
How complex can you get?
Complex systems and networks abound in the world around us. If you got caught in the morning traffic jam this morning you have witnessed one example. Paths in an ant hill or in a computer game are other examples.
And the neural network of nerves in your brain is another. What they all have in common is a very complicated organization. Networks can even be used to understand High School dating patterns!
We are modelling complex systems at our Graduate School to understand neural networks and vibrations of sponge like materials containing lots of holes.
Neural networks: human brain cells are being grown one by one on silicon substrates and elementary thought processes modelled. This amazing combination of organic and inorganic should lead to new hybrid devices
Fractal materials: matter with patterns that repeat down to smaller and smaller dimensions, like coral for example, are called fractal materials. If you bang a piece of coral and listen to it, you can hear it vibrating. These vibrations are called fractons.
Electrons in fractal materials are like bad schoolkids—they don’t do what you expect (which is interesting). So we calculate what these electrons do.
Make new matter!
Ever wanted to play God and create entirely new materials by yourself?
Did you know your snowboard contained new materials too?
It’s a fancy form of cookery for atoms, but you cannot eat what you get. In our Graduate School we are a hive of activity designing, making and testing new materials. From large lumps to minute molecular-sized pieces.
Quasicrystals: these are peculiar crystals with a semi-regular structure. They are usually made from metals. In two-dimensions there is a similar structure, called Penrose tiles.
What we do is to make new quasicrystals, and investigate their structure and physical properties.
Carbon nanotubes: these tiny nanometer (1 nm=10-9 m) sized tubes are the strongest known material and at the same time can be made to conduct electricity.
We are calculating how electrons move in these nanotubes. These may be the wires in your computer of the future.
What makes your iPhone work? Why semiconductors of course. Without them electronics would not exist as you know it.
Electrons in semiconductors behave in ways we can exploit to make gates through which electrons can stop or go only with the permission of other electrons. That allows us to build memories, switches and processing circuits.
We are pushing the size of such devices to ever smaller dimensions in our Graduate School, down to tiny atomic-sized dots or lines.
Dots: only a few atoms across, tiny islands of semiconductors have properties totally different from bigger samples. Each behaves like an atom in itself.
We are investigating new ways to grow dots in precise arrays, to provide parts for entirely new machines such as a quantum computer.
Quantum computer: Using the laws of quantum mechanics that apply to tiny objects, unimaginably strange machines can be built. One example is a quantum computer, predicted to be superfast.
Existing only on paper, this dream is rapidly becoming a reality. We are investigating the use of semiconductor dots to make gates for quantum computers.