Job type: PhD fellowship, full-time.
Start date: October 1, 2020 (later also possible).
Job duration: three years, working towards PhD degree.
Location: Faculty of Physics, Sofia University, 5 James Bourchier Blvd, 1164 Sofia, Bulgaria (EU).
PhD Advisor: Marin Bukov, PhD.
Requirement: successful applicants must hold a Master degree or its equivalent at the start date of the job.

Applications are now open for a VIHREN PhD fellowship (see also job ad for postdocs).

We are currently looking for highly motivated and skilled students to join a new research group at Sofia University. The group is funded by a VIHREN research frontier grant from the Bulgarian National Science Foundation, and a Marie Sklodowska-Curie actions grant from the European Commission’s Research Executive Agency. The group maintains an active network of international collaborations with leading groups in the field [Berkeley, Boston, Brussels, Harvard, Munich, etc.].

We are interested in a broad range of topics revolving around the field of quantum many-body systems [non-equilibrium quantum dynamics, condensed matter theory (phase transitions, critical phenomena), AMO physics, and statistical physics], developing techniques and ideas from Deep Learning for quantum systems. The students are expected to engage in active, full-time research, and work towards obtaining a PhD degree; they will be actively supervised by the principal investigator M. Bukov. The working language in the group is English.

VIHREN PhD fellowship benefits:

  • generous stipend
  • laptop
  • participation in international conferences, workshops, and schools
  • opportunities for collaboration with an international network of leading scientists in the field, and local experts.

The PhD thesis topic will be at the interface of far-from-equilibrium many-body dynamics (theoretical physics) and deep reinforcement learning (machine learning). The obtained results are expected to be applicable in experimental platforms, such as ultracold atoms, trapped ions, and superconducting circuits. The precise project will be selected based on the student’s preferences and can involve a combination of:
       (i) building analytical descriptions and approximate theories for understanding nonequilibrium many-body states of matter [e.g., periodically-driven systems, Floquet engineering, pre-thermalization and thermalization in integrable and nonintegrable models, quantum control and manipulation of exotic many-body states of matter, optimization landscapes and their complexity, etc.], and
       (ii) developing deep reinforcement learning (RL) algorithms specifically tailored for quantum systems [e.g., applying and assessing the performance of recent RL algorithmic breakthroughs to manipulate quantum systems, developing new hybrid RL-quantum control techniques specifically designed to interact with quantum systems, etc.].
Examples of past projects can be found on https://mgbukov.github.io/. After graduation, VIHREN PhD fellows will develop an in-depth research expertise, and a number of high-demand skills useful to pursue a career in both academia and industry.

The PhD project involves numerical simulations (with varying extent, depending on interests). Hence, basic knowledge of a programing language (Mathematica, Matlab, Python, C++, or similar) is required, except for analytical projects (but then the student will be expected to learn coding quickly). Familiarity with a quantum mechanics library [e.g., QuTip, QuSpin, TeNPy, iTensor, NetKet], or a machine learning package [e.g., TensorFlow, PyTorch, JAX] is not required but will be considered an advantage. The group has access to three hpc clusters and successful applicants will have the opportunity to learn state-of-the-art high-performance computing techniques and practices. The PhD advisor is one of the developers of QuSpin, and interested students can also participate in scientific software development. PhD students will be provided with a laptop as part of the VIHREN fellowship.

Scientific activities in the group will include a weekly group meeting to discuss recent progress in the field, and participation in journal clubs and seminars on topics of common interest. Group members may also be asked to help partially with the teaching activities the group is involved in. To build a friendly and productive working environment, VIHREN fellows – as an integral part of the group – will be cordially invited to join in non-scientific activities [Sofia lies in between Vitosha mountain and the Balkan mountains which provide many opportunities for outdoor activities, and enjoy four-season weather].

VIHREN PhD fellows are expected to enroll as PhD students. The stipend covers the PhD program tuition fees for EU/EEA students; non-EU/EEA students should also check the additional criteria for enrolling in a PhD program at Sofia University.


Application Materials: interested applicants should send the following materials to Marin Bukov at mgbukov(at)phys.uni-sofia.bg. Please, use the subject line “VIHREN PhD fellowship application”:

  1. CV (emphasize those strengths and skills relevant for this PhD position),
  2. the names and e-mail contacts of at least one Reference (we will contact them for letters of recommendation),
  3. transcript of records for your bachelor and master studies, and (if not present therein) a list of audit-only classes.

We strongly encourage both physics majors with interest in machine learning, and science majors with knowledge of quantum mechanics to apply for the VIHREN PhD fellowship! Generally, as long as you have a strong interest and background knowledge in some of the topics listed above, we will give serious consideration to your application, even if your major is not physics.


Sofia University “St. Clement of Ohrid” is the oldest research university in Bulgaria and one of the largest in south-east Europe, with about 20,000 students. Situated within walking distance from downtown Sofia in Sofia University’s Lozenets campus, the Faculty of Physics hosts research groups in various areas of modern physics, and has been enjoying the most productive research environment in Bulgaria [340 publications/yr. (Web of Science) in 2018]. The Quantum Optics and Quantum Information theory group hosts the annual workshop CAMEL (Control of quantum dynamics of Atoms, Molecules and Ensembles by Light). The Faculty of Physics shares campus with the Faculty of Mathematics & Informatics, and the Faculty of Chemistry & Pharmacy, providing opportunities for interdisciplinary collaborations. The Bulgarian capital Sofia also hosts the institutes for Solid State Physics and Informatics, and Information and Communication Technologies (ICT) at the Bulgarian Academy of Sciences, with groups interested in condensed matter, quantum optics, and ML/big data.


Competitive applicants will be invited for an interview on a rolling basis (apply early!). This position will remain open until filled, but we will have more openings in the following years. The position is open as part of the research project “Reinforcement Learning to Manipulate Quantum Matter away from Equilibrium”, funded by a VIHREN frontier research grant from the Bulgarian National Science Foundation.

Copyright © 2020 Marin Bukov