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 PhD position. The PhD student 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 qualifications
You will participate in a project team with several senior researchers and PhD students, which will design and fabricate quantum-dot-based SPSs meeting all the requirements of the quantum information applications. The focus of this PhD project is the experimental activities, including the microfabrication, electrical tuning 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 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 to use the Stark effect to stabilize 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 fabricate the state-of-the-art micropillar-based SPS devices with optimized designs. The primary responsibilities of the Ph.D. student are to:
- Perform e-beam and photo-lithography.
- Perform reactive ion etching and wet chemical etching.
- Perform thin film deposition.
- Implement electrical contacts for the tuning.
- Optical characterization of the fabricated devices.
- Supervise project students.
- Contribute to the development of new SPS designs.
You must have a two-year master’s degree (120 ECTS points) or a similar degree with an academic level equivalent to a two-year master’s degree. Additionally, the candidate must have passed an introductory course on quantum mechanics. The candidate must describe his/her previous experience with quantum mechanics in the cover letter (see below).
Approval and Enrolment
The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see the DTU PhD Guide.
The assessment of the applicants will be made by Assoc. Prof. Niels Gregersen, Assist. Prof. Battulga Munkhbat and Assist. Prof. Luca Vanucci.
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 appointment terms
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 3 years.
You can read more about career paths at DTU here.
Further information may be obtained from Assoc. Prof. Niels Gregersen, (firstname.lastname@example.org, tel.: +45 45253789) and Assist. Prof. Battulga Munkhbat (email@example.com). 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 www.fotonik.dtu.dk/english.
If you are applying from abroad, you may find useful information on working in Denmark and at DTU at DTU – Moving to Denmark.
Your complete online application must be submitted no later than 14 November 2021 (Danish 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:
- A letter motivating the application (cover letter)
- Curriculum vitae
- Grade transcripts and BSc/MSc diploma
- Excel sheet with translation of grades to the Danish grading system (see guidelines and Excel spreadsheet here)
- Name and email address of at least one reference, e.g. your MSc project supervisor.
You may apply prior to obtaining your master’s degree but cannot begin before having received it.
All interested candidates irrespective of age, gender, race, disability, religion or ethnic background are encouraged to apply.