27/08/2016 - On Wednesday 16th March 2016, a celebration of the life of our friend and colleague Danny Segal took place. There was a session of talks, followed by an evening of music. Videos from the event can be found here.
06/04/2016 - New publication: "Resolved-Sideband Laser Cooling in a Penning Trap". In this paper we report the cooling the axial motion of a single calcium ion to its quantum ground state using resolved-sideband laser cooling. This is the first time that this has been achieved in a Penning trap and has particular importance to the field of precision measurement, where this type of trap is widely used. We have also measured the motional heating rate in our system and have found it to be lower than any previously reported figure.
29/02/2016 - Congratulations to Graham Stutter on passing his PhD viva!
11/09/2015 - New publication: "Trapped-ion quantum error-correcting protocols using only global operations"
27/02/2015 - Congratulations to Joe Goodwin on passing his PhD viva!
07/03/2014 - New publication: "Optical sideband spectroscopy of a single ion in a Penning trap"
05/11/2013 - New publication: "Theory and simulation of ion Coulomb crystal formation in a Penning trap". In this paper we develop a theoretical model for the formation of small ion Coulomb crystals (ICCs) in a Penning trap, when the ions are subject to a radial laser cooling beam. We show that the rotation speed of the ICC is determined mainly by the parameters of the laser beam and not the trap, so long as the radial extent of the crystal is less than the diameter of the laser beam. This result has been confirmed by simulations of the system that take into account all the forces acting on the ions, including the trapping forces, the Coulomb interaction of the ions, and the interaction with the cooling laser beam.
07/10/2013 - New publication: "Control of the conformations of ion Coulomb crystals in a Penning trap". In this paper we report new images of an exotic state of matter formed by atomic ions that are held in a device called a Penning ion trap. The calcium ions are trapped by a combination of electric and magnetic fields and stay in the trap for hours at a time. They are slowed down till they are virtually stationary by a process of "laser cooling" where they are bathed in laser light at a very precisely known frequency. Once they are cold they arrange themselves in different configurations depending on the strength of the trapping fields. These "ion Coulomb crystals" are very similar to tiny conventional crystals like diamond except that the distance between the ions here is about 100 000 times bigger than the distance between atoms in a conventional crystal, so the density of the ion crystal is extremely low - roughly the same as the ultra-high vacuum inside the trap. The ion crystals can be photographed by a sensitive digital camera and we can manipulate the trapping fields to change the ion crystal shape from a linear string of ions through many different three-dimensional structures to a pancake-like crystal. All of these configurations can be reproduced in simulations. Ion Coulomb crystals have been observed and studied before in different sorts of ion trap but our research represents the most detailed study of all the different structures that are possible at this tiny scale. This work has potential applications in the area of "Quantum Simulation", where systems of atoms or ions are used to simulate quantum processes that cannot be studied using conventional computers.
18/07/2013 - We have a new website!!!