01/8/2017 -  Our new research grant from EPSRC entitled “Optimal Control for Robust Ion Trap Quantum Logic” starts.  This grant will support a collaboration between Richard Thompson (Experiment) and Florian Mintert (Theory) for 4 years. Link to the grant proposal can be found here. 

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!!!

27/8/1960 to 23/9/2015

On 16th March 2016 we celebrated the life of our colleague Danny Segal. Videos of the talks and musical performances can be found here.

It is with enormous sadness that we announce the death of our colleague Danny Segal, who was a truly exceptional person with a boundless enthusiasm for life, a passion for physics and a genuine empathy for others.

After completing a BSc in physics at the University of Manchester in 1983, Danny moved to the Physics Department at Imperial College, where he worked for his doctorate under Keith Burnett in the Spectroscopy Group (later to be absorbed into the Quantum Optics and Laser Science Group (QOLS)). His research involved the use of laser spectroscopic techniques to study the physics of atomic collisions: Danny had to establish a new laboratory virtually from scratch to complete his work and in doing so proved a most talented experimental physicist. It was soon clear to those who worked with him at the time what an admirable, sociable and good humoured colleague he was.

After Danny was awarded his PhD in 1988, Keith Burnett moved to Oxford, taking Danny with him as a post-doctoral research associate. In 1991, he returned to Imperial to join the ion-trapping activity under Richard Thompson. In 1993, Danny was awarded an EPSRC Advanced Fellowship for work using trapped ions in studies of cavity quantum electrodynamics. When the Fellowship ended, he was appointed to a Lectureship, and was subsequently promoted to Senior Lecturer in 2001, Reader in 2004, and Professor in 2011.

Danny’s research was mainly concerned with quantum optics experiments using laser-cooled ions in traps (particularly Penning traps), but his research interests also included electromagnetically-induced transparency and buffer-gas cooling of molecules. Danny was instrumental in the development of various novel Penning trap architectures, and in studies of the dynamics of trapped ions, culminating in the achievement of sideband cooling of a calcium ion in a Penning trap to the ground state of its motion.

Danny was passionate about his research and particularly enjoyed the challenge of undertaking technically difficult experiments. Over the years, his many research students have benefitted from his boundless enthusiasm and physical insight. As a supervisor, he was always able to find time to give his students all the support they needed, both for technical matters and also personal issues.

Danny gave generously of his time to supporting the smooth running of both the QOLS group and the physics department in general. As a teacher, he was the envy of many colleagues, because he had an ability to inspire students in an apparently effortless manner and to convey complex ideas with skill and humour. He was instrumental in the formation of the Centre for Doctoral Training in Controlled Quantum Dynamics, and the success of this venture is to a large extent due to the excellent MRes programme for which he was mainly responsible.

He was the first Warden of the Clayponds Hall of Residence for postgraduate students at Imperial College, and he succeeded in establishing an effective and supportive community for the students based there. For many years he was the postgraduate mentor for the QOLS group, offering confidential advice to students with a wide range of problems. Recently he served as the department’s Senior Tutor, a demanding role to which he was totally committed. He was hugely appreciated in this position by the entire student body, and had a reputation for understanding and compassion, while at the same time remaining completely professional in his dealings with students.

Outside the College he had a reputation for giving his time freely to encourage scientific collaboration and cooperation. Danny did more than his fair share of EU network administration from which many EU research groups working in laser cooling and quantum optics benefitted. At the ion trap Winter School at Les Houches in 2012, when one of the other lecturers was ill, it was Danny who took over at the last minute as a replacement and, as with his other activities, this was carried out with his characteristic professionalism.

Danny was diagnosed with a serious brain tumour in September 2014. There followed a long period of intensive treatment, which was ultimately unsuccessful. The positive and determined attitude he took to his illness has been a true inspiration to those who were able to see him over the last year: he retained his unique character throughout, and it was always a pleasure to chat to him. He continued to be actively involved in the ion trap group’s research programme until very recently. He also maintained his lifelong interest in playing the guitar and painting.

Danny will be greatly missed by all those who came into contact with him. He is survived by his wife, Helen, and two grown-up children, Rose and Jack.

16th March 2016

Afternoon session – Talks by Danny’s colleagues and associates

YouTube links for the individual talks

• Welcome - Head of Department (Jordan Nash)
• Poem: “Quantum Leap” by Rose Segal
• Danny as a fellow PhD student – Steve Young
• Danny as a research colleague – Richard Thompson (Imperial)
• Danny as a colleague in the ion trap community – Martina Knoop (Marseille)
• Danny as a colleague in outreach activities – Nic Harrigan (Bristol)
• Danny as a supervisor – Joe Goodwin (Imperial)
• Danny as the Senior Tutor – Ben Fernando (Imperial)
• Danny as a Departmental colleague – Peter Knight (Imperial)

A recording of the whole event is also available on the College website here

Evening session – reception and concert

Link to videos on the College website

• Informal musical performances by family, friends and colleagues