Imperial College London


Faculty of Natural SciencesDepartment of Physics

Professor of Experimental Physics



+44 (0)20 7594 3606r.thompson Website CV




Ms Judith Baylis +44 (0)20 7594 7713




620Blackett LaboratorySouth Kensington Campus




Overview - Laser cooled ions in a Penning trap

My research is concerned with the Physics of Trapped Ions (see

I have recently published a review of Ion Coulomb Crystals (in the journal Contemporary Physics) which can be downloaded from the following link:

We use the Penning trap for studies of the laser cooling process and for the preparation of single laser cooled ions.  Our experiments aim to use ions in a Penning trap for applications in quantum optics and quantum information processing.  Our current goal is to study the decoherence processes taking place when single ions are prepared in quantum superposition states in a Penning trap. Key highlights from our recent work in this area include:

  • Measurement of the first optical sideband spectra for an ion in a Penning trap for determination of the temperature of the all three degrees of freedom of the ion 
  • The first optical sideband cooling of a single ion in a Penning trap to the ground state of its quantum mechanical motion in the trap
  • Demonstration of one of the lowest anomalous heating rates worldwide for a single trapped ion
  • Demonstration of a very long coherence time, approaching one second, for superpositions of the motional states of the ion, both in the ground atomic state and in the excited stomic "qubit" state
  • Ground state optical sideband cooling of all the axial oscillation modes of small ion Coulomb crystals containing one to three ions

In work published in Nature Communications, we demonstrated that we can prepare ion Coulomb crystals containing small numbers of ions (between 1 and about 30 ions) in a wide variety of configurations including one-dimensional strings, two-dimensional planes and three-dimensional "solid" crystals by adjusting the laser cooling and trap parameters.

These experiments are supported by theoretical work and computer simulations.  Our recent results in this area were published in Applied Physics B.

We have developed various new designs for Penning traps including traps using permanent magnets and simple designs based on wires and planar electrodes.  Some of these novel designs trap have been built and tested in our laboratory.

We are also part of the HITRAP European Network which seeks to perform various experiments with trapped, highly charged atomic ions. Our role in this network is to perform laser spectroscopy of such ions.  These experiments will be carried out at the HITRAP facility at GSI in Darmstadt.  Progress towards this goal were published in Physical Review B in 2012.


Our work is funded by the EPSRC and the European Community.


Prof M B Plenio, University of Ulm

Prof W Noertershauser, GSI Helmoltz Centre for Heavy Ioan Research, Darmstadt, Laser Spectroscopy of Highly Charged Ions

Prof P Gill, National Physical Laboratory

Mr A Earis, Royal College of Music

Dr Danny Segal, Imperial College, QOLS Group

Dr A Sinclair, National Physical Laboratory, Ion Trapping

Guest Lectures

Spectroscopy and Quantum Optics with Penning traps, BARC, Mumbai, India, 2011

Research Staff



Research Student Supervision






Hrmo,P, Coherent manipulation of ions in a Penning trap




Stutter,G, Laser spectroscopy of trapped ions