PhD student in Physics: Data-Driven Response Theory for Complex Dynamical Systems

The Department of Physics is located in the AlbaNova University Center and has approximately 240 employees, 250 students at undergraduate level and 70 graduate students. There are four research subjects within the postgraduate program: Physics, Theoretical Physics, Chemical Physics and Medical Radiation Physics. These subjects span over several research groups with different research activities. For information about the Department of Physics, see: www.fysik.su.se/english.

Project description

Subject: Theoretical Physics

This PhD project aims to develop a mathematically grounded, data-driven framework to predict how complex, nonlinear dynamical systems respond to small perturbations. The project combines the Generalized Fluctuation–Dissipation Theorem (GFDT) from statistical physics with modern score-based generative modeling (SBGM) to estimate response functions without costly ensemble simulations or restrictive Gaussian assumptions. The key idea is to learn the score (the gradient of the log of the invariant density) directly from data and use it within the GFDT to compute response functions for general observables.

The student will (i) design and analyze score estimators tailored to response theory, (ii) extend the framework to cyclostationary systems and parameter calibration, and (iii) develop open, reproducible software. Applications will span reduced-order stochastic models and spatially extended systems relevant to fluid dynamics and climate, where non-Gaussian statistics and extremes are central.

The training blends stochastic processes, dynamical systems, and machine learning, with emphasis on interpretability, rigorous validation, and computational efficiency. The outcome is a versatile toolkit for sensitivity analysis, enabling principled prediction and control in nonlinear, non-Gaussian regimes.

Qualification requirements

In order to be admitted to postgraduate education, the applicant must have the general and specific entry requirements. The qualification requirements must be met by the deadline for applications.

You meet general entry requirements if you have completed a second-cycle degree, or completed courses equivalent to at least 240 higher education credits, of which 60 credits must be in the second cycle, or have otherwise acquired equivalent knowledge in Sweden or elsewhere.

Specific entry requirements. In order to be accepted as a PhD student in Physics or Theoretical Physics a BSc in Physics (or equivalent) is required. The studies must include 60 credits of second-cycle courses in physics out of which at least 15 credits correspond to a second-cycle degree project. The degree project does not have to have been examined at the application deadline, but work corresponding to half a semester of full-time studies should have been devoted to it. For the subject Chemical Physics courses in chemistry may replace the required physics courses. The subject Medical Radiation Physics requires a second-cycle degree project of 30 credits in the subject area, or with 60 credits of physics, a second-cycle degree project of 30 credits in another subject area.

In addition, proficiency in English language, equivalent to English B in Swedish high school, is required, or

• Previously completed University degree taught in English
• IELTS score (Academic) of 6.0 or more (with none of the sections scoring less than 5.0)
• TOEFL score of 550 or more (computer based test 213, internet based 79)
• Cambridge/Oxford - Advanced or Proficiency level.

Selection

The selection among the eligible candidates will be based on their capacity to benefit from the training. The following criteria will be used to assess this capacity:

• documented knowledge in a relevant field of research
• capacity for analytical and creative thinking
• initiative
• independence
• ability to collaborate
• written and oral proficiency in both Swedish and English.

Admission Regulations for Doctoral Studies at Stockholm University.

About the employment

We offer a fixed-term employment as a doctoral student according to Chapter 5 of the Higher Education Ordinance (1993:100). The period of employment may not be longer than what corresponds to full-time doctoral education for four years. As a doctoral student, you should primarily devote yourself to your own doctoral education, but the employment may include work with education, research and administration to a limited extent (maximum 20 %).

A new employment as a doctoral student is for a maximum of one year, the employment is then renewed for a maximum of two years at a time.

Stockholm University strives to be a workplace free from discrimination and with equal opportunities for all.

Contact

For more information about the project, please contact Prof. John Wettlaufer, john.wettlaufer@su.se.

For information about the employment Prof. Michael Odelius, odelius@fysik.su.se, who can also forward questions to the PhD student council at Fysikum.

Application

Apply for the PhD student position at Stockholm University's recruitment system. Attach a personal letter and CV as well as the attachments requested in the application form. It is the responsibility of the applicant to ensure that the application is complete in accordance with the instructions in the job advertisement, and that it is submitted before the deadline.

The instructions for applicants are available at: How to apply for a position.