Postdoc in Fabrication and Characterization of Quantum Light Sources

fredag 23 okt 20

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Frist 24. november 2020
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The Quantum and Laser Photonics Group at DTU Fotonik, Department of Photonics Engineering at the Technical University of Denmark, is seeking a candidate for a Postdoc position. The Postdoc will work in the field of microfabrication and quantum optical characterization of sources of single indistinguishable photons based on semiconductor quantum dots. The position is offered with support from the European Research Council.

Solid-state sources of single photons are expected to play an important role in various quantum information applications, such as secure communications, quantum computation and metrology. These applications require deterministic on-demand emission as well as high efficiency, purity and indistinguishability of the emitted photons. A promising platform for a deterministic single-photon source (SPS) is based on the semiconductor quantum dot (QD) in a solid-state environment. Until now the activities at DTU Fotonik have been limited to theory and modelling of SPSs, but with this opening we are launching also an experimental activity in this field. 

Responsibilities and tasks
You will participate in a project team with several Postdocs and PhD students, which will design and fabricate quantum-dot-based SPSs meeting all the requirements of the quantum information applications. Your overall responsibility will be to lead the experimental activities including the microfabrication and the optical characterization of the devices.

We will grow wafers with cavities with Stranski-Krastanov randomly distributed semiconductor InAs QDs surrounded by distributed Bragg reflectors in collaboration with the University of Würzburg. We will subsequently identify the randomly positioned QDs using an optical imaging technique, and we will etch pillar structures around the QDs. The lithography will be done using a combination of UV and e-beam lithography, and the etching will be performed using reactive ion etching, and possibly also wet chemical etching. The structures will be electrically contacted in order to use the Stark effect for stabilization of the local charge environment. For the optical characterization, the devices will be characterized placed in a cryostat and the QDs will be excited using resonant or quasi-resonant optical excitation. We will then characterize the single-photon emission in terms of purity, indistinguishability and efficiency. The experimental activity will take place in a close feedback loop with the theoretical activity to take into account the experimental results in subsequent design iterations, and the entire project team will discuss promising opportunities for next-generation SPS designs.

The candidate is thus expected to

  • Take responsibility for and lead an experimental activity.
  • Perform spectroscopy and optical imaging of QDs.
  • Perform UV and e-beam lithography.
  • Perform reactive ion etching and wet chemical etching.
  • Perform metal deposition.
  • Implement a setup for optical device characterization.
  • Characterize the devices in terms of efficiency, purity (Hanbury Brown-Twiss) and indistinguishability (Hong-Ou-Mandel).
  • Supervise experimental PhD students as well as project students.
  • Contribute to the development of new SPS designs.

Candidates should have a PhD degree or equivalent. Furthermore, preference will be given to candidates with 

  • Experience in cleanroom fabrication of nanophotonic devices (UV and e-beam lithography, spin-coating, reactive ion etching, wet chemical etching, metal deposition).
  • Experience performing optical characterization of light emitting devices in an optical lab.
  • Knowledge of quantum optics and of cavity quantum electrodynamics.
  • Knowledge of numerical simulations of the optical field using e.g. FDTD or FEM.
  • Willingness to work in close collaboration with an internal project team consisting both of theoreticians and experimentalists.
  • Willingness to supervise PhD, MSc and BSc students.

Additionally, the candidate should fit the following profile:

  • You strive to develop talent amongst others.
  • You thrive on collaboration and teamwork.
  • You are focused on the process as well as the outcome.
  • You believe in dialogue and feedback as the best foundation for sound decision-making.

The candidate should describe his/her qualifications in relation to the points above in the cover letter.

We offer
DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

Salary and terms of employment
The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is three years. The start date is February 1, 2021 (with some flexibility). 

You can read more about career paths at DTU here

Further information
Further information may be obtained from Niels Gregersen (, tel.: +45 45253789. (Applications submitted by email will not be considered, instead you should use the on-line portal described below.) 

You can read more about DTU Fotonik at

Application procedure
Please submit your online application no later than 24 November 2020 (local time)Applications must be submitted as one PDF file containing all materials to be given consideration. To apply, please open the link "Apply online", fill out the online application form, and attach all your materials in English in one PDF file. The file must include:

  • Application (cover letter)
  • CV
  • Diploma (MSc/PhD)
  • List of publications
  • Name and email address of 1-3 reference, e.g. your PhD supervisor

Applications and enclosures received after the deadline will not be considered. 

All interested candidates irrespective of age, gender, disability, race, religion or ethnic background are encouraged to apply. 

DTU Fotonik has 220 employees with competences in optics. In a typical year, DTU Fotonik educates 55 PhD students from more than 25 countries and our student numbers are constantly growing. As one of Europe’s largest public photonics research departments, DTU Fotonik covers a multitude of optical disciplines ranging from fundamental light-matter interaction and optical telecommunications to applied research and innovation. Our research topics include optical sensors, lasers, LEDs, photovoltaics, ultra-high speed optical transmission systems, bio-photonics, nano-optics and quantum photonics.

Technology for people
DTU develops technology for people. With our international elite research and study programmes, we are helping to create a better world and to solve the global challenges formulated in the UN’s 17 Sustainable Development Goals. Hans Christian Ørsted founded DTU in 1829 with a clear vision to develop and create value using science and engineering to benefit society. That vision lives on today. DTU has 12,000 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. Our main campus is in Kgs. Lyngby north of Copenhagen and we have campuses in Roskilde and Ballerup and in Sisimiut in Greenland.