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.
It's remarkable that we can talk about technologies when scientists today are still puzzling over what quantum theory tells us about nature. 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 the theory's mysteries. 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 the fact is, we don't have to completely understand quantum mechanics to make progress. 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. Many of the methods explored at CQT are as promising for what they could reveal about physics as they are for future applications.
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, some using atom chips. These experiments operate at temperatures close to absolute zero (-273K) so that thermal disturbances don't destroy the atoms' delicate quantum states.
One group proved its set-up by creating a Bose-Einstein condensate—an exotic phase of matter in which many atoms occupy a single quantum state and behave as one—at less than a millionth of a degree above absolute zero, making our lab 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 pages. Some outside sources are recommended in Further Reading. Check our home page for the most up-to-date news.