Exploring The Quantum Department of Physics Entering the FreezerThe Age of the Qubit HOTCOLD Quantum properties emerge at extremes of energy. We work with the coldest matter in the universe. AtomElectronQubit Quantum Matter Quantum Light Large Hadron Collider 3 Sun 2 Deep space 1 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. Laser-cooling techniques allow us to slow atoms which move at the speed of a jumbo jet almost to a standstill. Some of the most promising research areas focus on hybrid quantum devices, combining both light and matter. 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. The successful taming of the qubit will allow for advances in telecommunications, atomic clocks for GPS technology and quantum computing. 19 th Century20 th Century21 st 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. Bose Einstein condensate Adam West QUANTUM Cold atoms can be manipulated and investigated much more easily, and at low temperatures, quantum effects begin to manifest. 300 m/s5 mm/s 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. Some of the work we do aims to create individual photons by exploiting interesting properties of atoms. 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. 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 Single photon production – carefully tuned lasers and microscopic cells help in making a photon `turnstile’ Single photon state – quantum state tomography allows for comparison of experiment and theory Unusual types of matter, such as ultracold molecules or Rydberg atoms will hopefully help answer questions in both physics and chemistry. 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 Laser beams are used to cool, move, image and prepare the quantum state of atoms in our experiments. Atomic clocks Image credits: Fiber optic communication 4 Laser setup – blue light used to cool Strontium atoms almost to absolute zero Quantum computing 5