The development of quantum theory in the early 20th Century brought about a revolution in our understanding of the universe. The theory defies intuition: it says that particles can be in more than one place at once, that the actions of separate particles can be strangely coordinated, and that measurements have inbuilt uncertainty, no matter how accurate our tools. CQT scientists explore this bizarre quantum world and attempt to turn its quirks to our advantage. Harnessing the quantum behaviour of photons and atoms, the particles of light and matter, could lead to new technologies for communication and computation.
We already know about applications of quantum physics in computing, communication, and measurement. Today quantum technologies keep world time and enable secret messaging. It may not be long until they appear in our smartphones. The future could bring quantum computers that zip through calculations today's machines can't cope with – and what more? The history of scientific discovery shows that our imaginations cannot always predict the best outcomes of basic research. Would the inventor of the first mechanical calculator ever have dreamed of the internet?
We can talk about technologies – but that doesn't mean we know all there is to know about quantum physics. Despite the theory being more than 100 years old, some quantum phenomena are as mind-boggling now as when Niels Bohr, one of the theory's founding fathers, said "anyone who is not shocked by quantum theory has not understood it". Some of CQT's research concerns open questions. For example, our scientists have discovered a possible new principle of nature (information causality) and linked the phenomenon that Einstein called "spooky action at a distance" to Heisenberg's Uncertainty Principle.
But even as CQT's researchers ask deep questions, they are inventing and improving technologies that let us study and do useful things with quantum behaviour.
We know that computers which process information 'quantumly' could solve some types of problems faster than today's classical computers. We also know that quantum laws enable new schemes to send secret messages securely, a field of research known as quantum cryptography. Related to this, our researchers are working on theory problems such as designing algorithms for quantum computers, and on experimental problems such as creating and manipulating quantum 'entanglement' between photons. Entanglement is what lets quantum particles coordinate their behaviour, and it's the magic ingredient in many quantum computation and communication schemes.
Atoms and photons are likely to be the working bits, used to store and transmit data, of any future quantum information devices. These same building blocks feature in proposals for other quantum technologies, such as precision measuring devices. Experimental groups at CQT are testing various ways to gain mastery over atoms and photons and their interactions. It's hard to predict what lab techniques will lead to useful technologies.
In the labs
As well as our experiments on photons, we have experiments that trap clouds of atoms with laser light and with magnetic fields. These experiments operate at temperatures close to absolute zero (-273K) so that thermal disturbances don't destroy the atoms' delicate quantum states.
When you make the right kind of atoms cold enough, they form a Bose-Einstein condensate—an exotic phase of matter in which many atoms occupy a single quantum state and behave as one. Groups at CQT have been achieving this feat since 2009. The condensate forms at less than a millionth of a degree above absolute zero, making CQT the coolest place on the Equator! It is also possible to trap a single atom, and another of our groups has observed its "shadow", that is the light that it blocks.
Some of our newest experiments will use cold atoms as "quantum simulators" of other types of matter. One idea is to simulate graphene to better understand its properties. Graphene is the two-dimensional carbon material for which the 2010 Nobel Prize in Physics was awarded. Other possibilities include studying the phenomena of superfluidity and superconductivity.
For a more thorough (and more technical) overview of our research activities, you can tour the "Quantum World" in the main CQT Research page or browse our recommended books. Check our home page for the most up-to-date news.