1. Department of Physics Exploring The Quantum Adam West Entering the Freezer The Age of the Qubit Quantum properties emerge at extremes of energy. We work with the coldest matter in the universe. The quantum world has revealed itself over the past 100 years. Instead of investigating quantum effects we are now trying to harness them for modern day applications. Through this exploration the object of focus shifted from the atom, to the electron, to the qubit. COLD HOT QUANTUM QUANTUM Large Hadron Collider3 Sun2 Atom Electron Qubit 19th Century 20th Century 21st Century Whilst classical computers store information in ‘bits’ which can be in the states ‘0’ or ‘1’, qubits are governed by quantum mechanics and thus can take the states ‘0’, ‘1’, both at once, or anything in between. Exploiting the laws of quantum mechanics we envisage an exponential increase in the data that we can store and process. Deep space1 Laser-cooling techniques allow us to slow atoms which move at the speed of a jumbo jet almost to a standstill. Bose Einstein condensate Fiber optic communication4 300 m/s 5 mm/s Atomic clocks Quantum computing5 The successful taming of the qubit will allow for advances in telecommunications, atomic clocks for GPS technology and quantum computing. Cold atoms can be manipulated and investigated much more easily, and at low temperatures, quantum effects begin to manifest. Quantum Matter Quantum Light We work with many types of quantum matter – atoms, molecules, ions and plasmas. By careful study of their behaviour we can discover the way in which they interact. At low energies we can observe quantum phenomena such as wave-particle duality or quantum tunnelling and interference. Just as all matter is made of atoms, the fundamental building block of light is the photon. A close examination of the behaviour of light can yield unusual phenomena. Lasers harness the quantum nature of matter to produce light. Most of our work uses laser light in some way. Matter wave interference – at low temperatures we observe that atoms begin to behave like waves, showing interference patterns We use a number of techniques to investigate, manipulate and control quantum matter, such as optical lattices, microfabricated chips, magnetic traps and nanometric vapour cells. Laser setup – blue light used to cool Strontium atoms almost to absolute zero Laser beams are used to cool, move, image and prepare the quantum state of atoms in our experiments. Single photon production – carefully tuned lasers and microscopic cells help in making a photon `turnstile’ Some of the work we do aims to create individual photons by exploiting interesting properties of atoms. Nanomagnetic atom mirror – millions of tiny magnets work together to make atoms bounce Optical lattice – atoms are suspended by laser light in an eggbox-like pattern Unusual types of matter, such as ultracold molecules or Rydberg atoms will hopefully help answer questions in both physics and chemistry. Some of the most promising research areas focus on hybrid quantum devices, combining both light and matter. Single photon state – quantum state tomography allows for comparison of experiment and theory Image credits: 1 http://goo.gl/cqt8k, 2 http://goo.gl/4SORK, 3 http://goo.gl/uaUae, 4 http://goo.gl/6bBZ1, 5 http://goo.gl/H4Keo Rydberg atom – highly excited, strongly interacting atoms grow to a micron in size Ultracold molecule – combining laser-cooled atoms allows us to form molecules devoid of energy