Lunds universitet, LTH, Fysiska institutionen

Lund University was founded in 1666 and is repeatedly ranked among the world’s top universities. The University has around 45 000 students and more than 8 000 staff based in Lund, Helsingborg and Malmö. We are united in our efforts to understand, explain and improve our world and the human condition.

Lund University welcomes applicants with diverse backgrounds and experiences. We regard gender equality and diversity as a strength and an asset.

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. 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 has been used to control the speed of light in the crystals. This has had some remarkable consequences as further described below.

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.

Four different working areas relevant for the position are described below.

Area 1: Experimental quantum information in rare-earth-ion doped crystals

Quantum information in general concerns the science of utilising quantum systems and the laws of quantum mechanics to get a performance better than can be obtained with classical information devices and techniques. Our quantum hardware is inorganic crystals doped with rare earth ions. As a solid-state system rare-earth-ion doped crystals are unique because of their millisecond optical coherence times, i.e. several orders of magnitude longer than in most other solid state systems and the spin coherence times of more than 6 hours. Further, a strong and controllable dipole-dipole interaction between ions that are close to each other in space can provide reliable quantum gate operations. Current work includes developing a capability to read out the quantum state of individual rare earth ions in rare-earth-ion doped crystals by enhancing the emission from ions by using a micron-sized cavity and development of high fidelity quantum gate operations. The high fidelity gate operations includes using extensive spectral tailoring and quantum state preparation and control tools that we have available.

Area 2: Laser stabilization using slow light rare-earth-ion-doped crystal cavities

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 variations are ~0.1 proton radius. We have 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. We will participate in the EU project “Next generation ultrastable lasers” (NEXTLASERS) together with several metrology groups in Europe.

Area 3: Using narrowband high suppression and low loss slow light filters to enable deep 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 rare earth materials, we can create very narrow filters that use a combination of absorption and slow light effects to separate frequency shifted photons from a carrier. We have made calculations that show that such filters can enable non-invasive optical imaging of deep lying organs, such as the heart. In this project, we 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 in deep tissue medical diagnostics, as optical imaging allows a molecular sensitivity not readily available in 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

Present work includes Maxwell-Block simulations of coherent interactions between multi-level ground and excited states in rare earth crystal. This type of simulations are important to understand and predict outcomes of both our quantum information and slow light experiments. We have recently carried out extensive work looking into the possibility to develop scalable schemes for quantum computing in rare earth ion doped crystals. We also carry out various light propagation simulations in order to model and understand our deep tissue imaging experiments.

Work duties

This is a 2-year position, where we are looking for a qualified candidate with the ability to efficiently contribute to the research in the group directly or with a short learning period. Teaching, up to 20% of working hours, may be included in the position and there are opportunities for training in higher education and learning. The researcher is expected to supervise/assist to supervise degree projects/doctoral students and if appropriate seek external funding. To a smaller extent the work may include outreach and administrative duties related to the projects.

Qualification requirements

A successful applicant must have:

  • A PhD or equivalent research qualification within the subject position
  • Two or more years research experience beyond the PhD of relevance for the subject of the position
  • Very good oral and written proficiency in English

Assessment criteria and other qualifications

  • The candidate should have the ability to run projects independently but also be able to interact efficiently with the other members in the research team.
  • We are looking for a candidate with knowledge and ability to contribute to both our simulation/theory work on coherent light-matter interaction and our experimental laser-based research on coherent systems. 

Good ability to cooperate, matched with drive and independence are important, as well as how the candidate’s experience and competence complement and strengthen the research and the future development of the group.

Terms of employment

This is a full-time, fixed-term employment of a maximum of 2 years.

Instructions on how to apply

Applications shall be written in English and should be completed into a PDF-file containing:

  • résumé/CV, including a list of publications
  • a general description of past research and future research interests (no more than three pages),
  • contact information of at least two references,
  • copy of the doctoral degree certificate, and other certificates/grades that you wish to be considered
Type of employment Temporary position
Contract type Full time
First day of employment 2021-07-06
Salary Monthly salary
Number of positions 1
Full-time equivalent 100
City Lund
County Skåne län
Country Sweden
Reference number PA2021/1194
  • Professor Stefan Kröll, +4646 222 9626
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.Apr.2021
Last application date 14.May.2021 11:59 PM CEST

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