Lund University, Faculty of Engineering, Department of Physics

Lund University was founded in 1666 and is repeatedly ranked among the world’s top 100 universities. The University has 40 000 students and 7 400 staff based in Lund, Helsingborg and Malmö. We are united in our efforts to understand, explain and improve our world and the human condition.

LTH forms the Faculty of Engineering at Lund University, with approximately 9 000 students. The research carried out at LTH is of a high international standard and we are continuously developing our teaching methods and adapting our courses to current needs.

The Department of Physics is with a staff of about 350 scientists and educators one of the largest departments within Lund University. There are seven research divisions and a number of research centra within the department. The research activities at the department cover a broad spectrum of modern physics.

The Quantum Information Group at the Division of Atomic Physics has a strong activity in quantum information and quantum optics based on light-matter interactions in inorganic crystals doped with rare earth ions. These materials have unique properties as solid state quantum materials due to their exceptionally narrow optical line widths, which also translates to an ability to remain in quantum superposition states over extended periods of time. Rare-earth–ion-doped crystals are also, together with trapped ions and superconducting qubits, one of three quantum computing schemes supported in the first round of the European Union Flagship on Quantum Technology. The group has been a pioneer in introducing quantum memory schemes in rare-earth-ion-doped crystals, a field in which many groups are active today. We have pioneered sophisticated structuring of the inhomogeneous absorption profiles of rare earth-ion doped crystals using optical pumping methods. Recently, this structuring has been used to control the speed of light in the crystals, with some remarkable consequences as further described below. The position is linked to the Quantum Information Group at the Division of Atomic Physics.

Subject description  The group works on the development of hardware for quantum computing and quantum memories and on developing materials where the speed of light can be slowed by 3-5 orders of magnitude for applications in e.g. laser frequency stabilization and medical imaging and treatment.

Area 1: Experimental quantum information in rare-earth-ion doped Crystals Quantum technology with rare-earth ions in solids is a fast growing field that has been recognized in the EU Flagship as the only contender to the two main approaches (superconducting qubits and ion traps). Rare-earth-ion doped crystals are unique among solid state systems because of their millisecond optical coherence times. These are then combined with spin coherence times of more than 6 hours. There is also a strong and controllable dipole-dipole interaction between ions that are close to each other in space and this interaction can provide reliable quantum gate operations. The main benefits are good interconnectivity of the qubits and a potentially very high qubit density. However, at present only a single full qubit has been realized, which means that the coming few years will be very impactful in demonstrating the potential of the rare-earth approach. The primary challenge right now is developing detection and interactions with single ions inside the crystals. We are pursuing several approaches for this, including coupling different qubit and readout ion species and also enhancement using micro cavity QED effects. Once this has been established, the strong dipole-dipole interactions between the ions can be used to extend the work to the multi-qubit regime, and to explore the high qubit scaling potential.

Area 2: Slow and fast light using slow light rare-earth-ion-doped crystals for metrology The frequency stability of lasers locked to reference cavities is presently limited by the thermal Brownian motion of the atoms constituting the reference cavities, which causes the length of the cavity to fluctuate with time. The current limit for the average cavity length variation is ~0.1 proton radius. We have recently demonstrated that slow light effects in Fabry-Pérot cavities made of rare-earth-ion-doped crystal materials can decrease cavity mode spacing and line widths by 3-5 orders of magnitude. Further we have shown that in such cavities the effect of length fluctuations on the cavity resonance frequency is decreased by 3-5 orders of magnitude compared to a conventional vacuum cavity of the same length. This project aims to explore the possibility to use this type of cavities for improving laser frequency stabilization beyond the current limits, partly in cooperation with SYRTE (Systèmes de Référence Temps-Espace) in Paris. At the other end of changes to the speed of light, we would also like to investigate the possibility to use fast light (pulses travelling faster than c), to increase the sensitivity for certain applications, e.g. gravity wave detection.

Area 3: Rare-earth spectral filters that can enable tissue imaging and treatment beyond what is possible today This project presents a unique opportunity to work in the border between advanced atomic physics and applied medical imaging. By using our techniques to spectrally program the rare-earth materials, we can create very narrow filters that use a combination of absorption and slow light effects to separate shifted photons from their carrier. We have made calculations that show that these filters can be used to enable non-invasive optical imaging of deep lying organs, such as the heart. In this project, we will strive to develop filters and laser technology that can then be tested together with researchers in medicine and biomedical engineering. Successful tests could have a significant impact on medicine in general, as this kind of optical imaging allows a molecular sensitivity not available to current techniques like ultrasound and x-rays.

Area 4: Theory and simulations – possible topics may include light-matter interactions, quantum computing schemes or simulation of light propagation in tissue Similar as described for experimental quantum information above (area 1), theory work related to rare-earth-ion quantum information has considerable potential for generating important results in the near future. A large part of the current protocols and schemes for quantum computing was developed with other approaches in mind, which means that novel schemes for rare-earth ions, using their unique features may have high impact.

We are also working with light propagation simulations to understand slow and fast light behavior, as well as for deep tissue imaging. There are also rare-earth-based slow light related medical applications where analysis of phase conjugation schemes for tissue imaging could be of significant importance.

Work duties The main duties involved in a post-doctoral posistion is to conduct research. Teaching may also be included, but up to no more than 20% of working hours. The position shall include the opportunity for three weeks of training in higher education teaching and learning.

Which research project/projects the succesful candidate(s) will be involved in is decided in discussions with the candidate. The duties may include teaching (however at the most 20%), again this possibility will be discussed with the succesful candidate. The postdoctoral researcher is expected to assist in supervision of degree projects and in part also in supervision for postgraduate students. Depending on his/her experience we may also offer the candidate training in applying for external funding. For the interested candidate we also expect to have outreach projects such that the postdoctoral researcher could collect experience from such tasks.

Qualification requirements Appointment to a post-doctoral position requires that the applicant has a PhD, or an international degree deemed equivalent to a PhD, within the subject of the position, completed no more than three years before the last date for applications. Under special circumstances, the doctoral degree can have been completed earlier.

Additional requirements:

  • Very good oral and written proficiency in English.

Assessment criteria and other qualifications This is a career development position primarily focused on research. The position is intended as an initial step in a career, and the assessment of the applicants will primarily be based on their research qualifications and potential as researchers. Particular emphasis will be placed on research skills within the subject.

For appointments to a post-doctoral position, the following shall form the assessment criteria:

  • A good ability to develop and conduct high quality research.
  • Teaching skills.
  • We are searching for a person with ability to run projects independently but also able to interact efficiently with the other members in the research team.
  • We expect the successful applicant to have extensive experience in experimental laser-based research and optics.
  • Programming experience is considered required for the theoretical work, and a plus for the experimental

Additional assessment criteria:

  • Documented prior teaching experience
  • Experience in coherent light-matter interactions

Strong consideration will also be given to good collaborative skills, drive and independence. How the applicant’s experience and skills can complement and strengthen our ongoing research activities within the Quantum Information Group, and how the applicant might stand to contribute to its future development, will also be of significant importance.

Terms of employment This is a full-time, fixed-term employment of a maximum of 2 years. The period of employment is determined in accordance with the agreement “Avtal om tidsbegränsad anställning som postdoktor” (“Agreement on fixed-term employment as a post-doctoral fellow”) between Lund University, SACO-S, OFR/S and SEKO, dated 4 September 2008.

Instructions on how to apply Applications shall be written in English. Please draw up the application in accordance with LTH’s Academic qualifications portfolio – see link below. Upload the application as PDF-files in the recruitment system. Read more:



Type of employment Temporary position longer than 6 months
Contract type Full time
First day of employment as soon as possible
Salary Monthly paid
Number of positions 1
Working hours 100
City Lund
County Skåne län
Country Sweden
Reference number PA2018/3425
  • Stefan Kröll, professor, +4646 2229626,
Union representative
  • OFR/ST:Fackförbundet ST:s kansli, 046-222 93 62
  • SACO:Saco-s-rådet vid Lunds universitet, 046-222 93 64
Published 30.Nov.2018
Last application date 21.Dec.2018 11:59 PM CET

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