PhD scholarship in Quantum State Preserving Frequency Conversion

The Fiber optics, devices and nonlinear effects group at DTU, Department of Photonics Engineering (DTU Fotonik), is looking for an excellent candidate for a PhD position to explore application of four-wave mixing in multimode optical fibers for manipulation of quantum states of light. Our ambition is to explore processing of, for example, single-photon states and in particular, frequency conversion of a single photon by utilizing four-wave mixing among multiple fiber modes. The ability to perform quantum-state-preserving frequency conversion is key to quantum communication networks where it is necessary to interface low-loss optical fibers with quantum components such as efficient single-photon detectors, single-photon sources or even quantum repeaters. 

The core focus of the proposed project is experimental demonstration of quantum-state-preserving frequency conversion using multimode optical fibers. The project will lay the foundation for additional research within generation and processing of quantum states in optical fibers.

The project is part of a larger project focused on wideband frequency conversion using nonlinear fiber optics funded by the independent research fund Denmark and will take place at DTU Fotonik.

You will become part of a team with expertise in design and characterization of optical fibers optimized for nonlinear optical phenomena. The activities within the project will benefit from synergies with other projects in the group as well as with other activities at the department, notably in the center of excellence “Silicon photonics for optical communication”.  

The project
Recent development in optical fibers have enabled fabrication of fibers that support multiple stable modes simultaneously, this include so-called linearly polarized modes as well as modes having a non-uniform state of polarization across the beam as for example modes carrying orbital angular momentum, radially polarized modes as well as azimuthally polarized modes. This platform has paved the way for utilization of intermodal nonlinear effects in optical fibers to achieve for example ultrahigh capacity optical communication systems or fiber lasers emitting ultrahigh power beams. One specific favorable application of intermodal nonlinearities is to achieve phase matching over unprecedented bandwidth in four-wave mixing. In the proposed project you will participate in a team with both senior researchers and other PhD students aimed at demonstrating generation and processing of quantum states using intermodal nonlinear effects in multimode optical fibers.

You will learn the basic principles behind nonlinear effects in state-of-the-art multimode fibers and, in particular, intermodal four-wave mixing. Your primary task will be to demonstrate quantum-state frequency conversion over wide bandwidths or in configurations where the output frequency is tunable. You will also have the opportunity to be trained in general design and characterization of state of-the-art optical fibers. Depending on the success of the experimental demonstration, you will have the opportunity to demonstrate the designed devices in state-of-the-art quantum key distribution laboratories.

The ideal candidate
We are looking for an engineer or physicist with a MSc level degree or equivalent who has excellent academic records and/or has demonstrated scientific achievements. We are interested in working with candidates who are highly motivated, self-driven and have demonstrated excellence in experimental photonics, and preferably passed an introductory course on quantum optics. Other qualities of the successful candidate include:

• academically curious and strong in thinking deeply and creatively
• high degree of responsibility for the progress and quality of their projects.
• willingness to develop any required skills and knowledge
• a good team player
• communicates well in both written and spoken English
• is empathetic and enjoy working with others having diverse backgrounds.

You must have a two-year master's degree (120 ECTS points) in photonics, applied physics or similar and obtained an academic level equivalent to a two-year master's degree.

Furthermore, you will:

• actively collaborate with the national and international partners of the project
• engage in DTU’s teaching activities e.g. supervise Bachelor and Master Project students
• participate in international conferences, compose scientific manuscripts for publications, and take part in outreach activities.

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 .    

Assessment
The assessment of the applicants will be made by. Prof. Karsten Rottwitt and Senior Researcher Lars Rishøj and Post doc. Jacob G. Koefoed.

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 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.Starting date: as soon as possible.

You can read more about career paths at DTU here . 

Further information
Further information may be obtained from Prof. Karsten Rottwitt. Applications submitted by email will not be considered, 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 .  

Application procedure
Your complete online application must be submitted no later than 15 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 ).

You may apply prior to ob­tai­ning your master's degree but cannot begin before having received it.

Incomplete applications will not be considered. Applications received after the deadline will not be considered.

All interested candidates irrespective of age, gender, race, disability, 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 12,900 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. DTU has campuses in all parts of Denmark and in Greenland, and we collaborate with the best universities around the world.