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Recruitment Status

Project no. Host Status

ESR1 AU filled
ESR2 UNIBAS filled
ESR3 CNRS/LKB filled
ESR4 UOXF filled
ESR5 UDUS open
ESR6 UIBK filled
ESR7 UULM open
ESR8 UBO open
ESR11 CNRS/LAC filled
ESR12 UNIBAS filled


ER AU filled

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13 experimental/theoretical PhD positions within the Marie Curie Initial Training Network:  Cold Molecular Ions at the Quantum limit (COMIQ)

COMIQ is an European Commission funded network focused at educating Early Stage Researchers (ESR) at the PhD level within a range of advanced cooling, trapping, and control techniques with the purpose of developing cold molecular ion research beyond its present state.

The aim of COMIQ is to investigate and control a variety of molecular ion processes at the very quantum limit. COMIQ will work on establishing cold molecular ions as new quantum objects for applications in quantum technology, precision measurements, and controlled chemistry. The network is highly interdisciplinary, combining quantum optics, quantum information sciences, molecular physics, and chemical physics in a novel and original fashion. We therefore invite strong candidates from all relevant disciplines to apply for a fellowship. Each fellowship has its own distinct profile and we wish the same for our future ESRs.

The network consists of ten partners, both academic and industrial, and all ESRs will be seconded at least once during the fellowship at another partner site. The 13 PhD positions, which are in short described below with indication of planned place of secondment, are available from November 1st, 2013. Most of the fellows are expected be hired within the first six months from this date, but later starting dates can potentially be accepted.

Eligibility Criteria

Research experience 0-4 years counted from the diploma that gives the rights to embark in a doctoral degree. The researcher must not have resided or carried out his/her main activity (work, studies, etc) in the country of his/her host organisation for more than 12 months in the 3 years immediately prior to his/her recruitment. Short stays, such as holidays, are not taken into account.

How to apply?

Send the following documents to the supervisor of your preferred project:

  • Motivated application (approx. 1 page)

  • Marks sheets

  • Resumé of Master's thesis (approx. 1 page)

  • Short CV

as well as your name and address. The descriptions of the fellowships can be found below

Any questions may be submitted to this address:

Download the advert (pdf)


2014.08.01 | COMIQ

1st COMIQ Newsletter

The first COMIQ newsletter is out now.

Alexander Dörfler

2014.07.28 | COMIQ

Alexander Dörfler joins COMIQ

Alexander Dörfler joins the group of prof. Stefan Willitsch in Basel on 1 August.

Steffen Meyer

2014.07.01 | COMIQ

Steffen Meyer joins COMIQ

Steffen Meyer joined the Ion Trap Group of Prof. Michael Drewsen, Aarhus University, on 1 July 2014.

Showing results 1 to 3 of 14

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Still open positions

Please find below the descriptions of the still open positions. 

ESR5: High-efficiency preparation of a single quantum state of a molecular ion and a high-precision spectroscopic determination of a fundamental mass ratio

Supervisor: Stephan SchillerHHU

Host Institution: Heinrich Heine University of Düsseldorf

Duration: 36 months

Planned secondment: Aarhus University


In our group, we are focusing on a particular molecular ion, HD+. This is a useful model system for testing techniques that can be of more general utility in the field of heteronuclear molecular ions, but it is of significant interest also in its own right, beign a fundamental quantum system.

HD+ is a three-body bound quantum system that can be accurately described ab initio by Quantum Electrodynamics, using as input certain fundamental constants, in particular the Rydberg energy and the two mass ratios of the three constituent particles. A comparison between experimental HD+ transition frequencies and the ab initio results therefore provides a test of the validity of theoretical treatments, and/or a determination of these fundamental constants. At present, the experimental inaccuracies of the transition frequency measurements is still higher than the theoretical or fundamental constants inaccuracies, resulting in an on-going experimental challenge.

We have performed many seminal experiments on cold molecular ion spectroscopy over the last decade, including laser-based rotational cooling, resonance-enhanced multi-photon dissociation, pure rotational excitation, fundamental vibrational spectroscopy. We also demonstrated addressing of individual hyperfine states of ro-vibrational levels by excitation of individual hyperfine transitions, and controlled transfer of population into a selected hyperfine state. On the theory side, we have worked extensively on the systematic frequency shifts of HD+, a very important topic if precision measurements are pursued.

References on this work can be found in the publication list at

In the open position, developments will be pursued that are aiming at increasing significantly the efficiency and accuracy of precision spectroscopy of HD+.

In detail, the task will be:

  • Develop an ion trap for storing a single atomic and a single molecular ion, sympathetically cooled.
  • Integrate a laser-based scheme for population effectively a single hyperfine state
  • Integrate a scheme for reading out efficiently the population of a single hyperfine state
  • Apply preparation and read-out techniques to various forms of high-resolution spectroscopy (radio-frequency, pure rotational, and ro-vibrational spectroscopy)
  • Compare the measured transition frequencies with the ab-initio theory values in order to validate the ab-initio theory calculations, and combine the results of the various spectroscopic measurements to determine an improved value of the mass ratio electron mass - reduced nuclear mass

The work will be done in a team comprising several Ph.D. and Master's students, a senior researcher and supported by a team of electronics engineers. See also our flyer.

ESR7: Formation and reactions of cold (BaRb)+ and Rb2+ molecules

UULMSupervisor: Johannes Hecker Denschlag

Host Institution: Ulm University

Duration: 36 months

Planned secondment: University of Bonn, Aarhus University, University of Basel


In our BaRbIe experiment we immerse a single cold trapped Barium (Ba) [or Rubidium (Rb)] ion in an ultracold gas of neutral Rb atoms. In this very unique and novel set-up we can study for the first time interactions of ions and atoms at ultralow temperatures.

Compared to the short ranged van der Waals interactions between neutral particles, atom ion interactions are long range due to the 1/r4 polarization potential.  We investigate how ions and atoms collide and react in the cold regime.  

An important goal is to transfer quantum control techniques that have in recent years been developed for ultracold neutral  quantum gases to atoms and ions. For example, we want to demonstrate Feshbach resonances in collisions between ions and atoms, which can be used to control the interactions of the particles and to form cold ionic molecules. We then want to study the properties of these molecules and measure how quickly they relax to more deeply bound states when they collide with cold atoms.  The applicant will join these efforts to move forward the frontier of ultracold chemistry between atoms and ions.


  • Population distribution of product states following three-body recombination in an ultracold atomic gas. A. Härter, A. Krükow, M. Deiß, B. Drews, E. Tiemann, and J. Hecker Denschlag, Nature Physics 9, 512 (2013)
  • A single ion as a three-body reaction center in an ultracold atomic gas , A. Härter, A. Krükow, A. Brunner, W. Schnitzler, S. Schmid, and J. Hecker Denschlag, Phys. Rev. Lett. 109, 123201 (2012)
  • Dynamics of a cold trapped ion in a Bose-Einstein condensate, Stefan Schmid, Arne Härter, Johannes Hecker Denschlag, Phys. Rev. Lett. 105, 133202 (2010)


ESR8: Coherence and decoherence of a single-ion qubit immersed into an environment

UBOSupervisor: Michael Köhl

Host Institution: University of Bonn

Duration: 36 months

Planned secondment: University of Basel


In quantum information processing it is important to manipulate a qubit in a coherently controlled way. Trapped atomic ions have been successfully employed in this field, since they are very well isolated from the environment and therefore offer long coherence times. However, when an isolated ion is coupled to an environment, it will become gradually entangled with many degrees of freedom and therefore eventually decoheres [1,2,3]. Therefore the question remains of how quantum computing could work under realistic conditions (i.e. when there is a finite coupling between qubit and the environment), and how it could potentially be optimised.

In this project, we plan to investigate decoherence mechanisms of a single or a few trapped ions controllably coupled to an environment. Particular focus will be on the question whether the environment could also be used as a resource to generate or protect entanglement between ions. We plan to investigate this process by carefully tailoring the properties of the environment, for example its dimensionality or the coupling strength between ion and environment. To this end, the project is concerned with the design, buildup and operation of the next generation of hybrid ion traps, where the tools for fast preparation and detection of the ion‘s spin coherence are already integrated into the trap. Specifically, we plan to employ recently developed optical fiber cavities [4] as an integral part of a new setup.


[1] L. Ratschbacher et al., Phys. Rev. Lett. 110, 160402 (2013).
[2] L. Ratschbacher et al., Nature Physics 8, 649 (2012).
[3] C. Zipkes et al., Nature 464, 338 (2010).
[4] M. Steiner et al., Phys. Rev. Lett. 110, 043003 (2013).

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Revised 2014.08.01