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Theoretical Quantum Optics

Research Group for Quantum Information and the theory of Open Quantum Systems headed by Prof. Dr. Otfried Gühne and Prof. Dr. Stefan Nimmrichter

Emmy Noether Campus

Our research profile

Our research group focuses on foundational questions in quantum information and open quantum systems. A first major topic is the phenomenon of quantum entanglement between two or more particles. Here, we are developing analytical approaches to characterize the different forms of entanglement and their usefulness.

A second major topic is quantum thermodynamics. There, we extend and refine the thermodynamical laws using tools from quantum optics and information theory in order to understand how microscopic quantum systems exchange heat, work, and information with their environment. 

Third, we are developing methods to analyze and improve quantum information processing devices using tools like shadow tomography or error mitigation.

In this research, the group forges a bridge from advanced mathematical methods to collaborations with experimentalists. We work closely with other groups doing quantum science at the University of Siegen. In addition, we collaborate with many partners around the world, e.g., from Austria, Brazil, China, France, Poland, Spain, and Sweden.

Main research areas

  • Multi-particle Entanglement
  • Graph States and the Stabilizer Formalism
  • Theory of Measurements in Quantum Mechanics
  • Open Quantum Systems
  • Bayesian Metrology
  • Shadow Tomography

Our courses

We offer various lectures and courses for the Bachelor's degree program in Physics, the Master's degree program in Physics, and the Master's degree program in Quantum Science program. The courses of the current semester can be viewed and booked on unsiono and can be booked. The regularly offered courses are

  • Introduction to Quantum Theory
  • Concepts of Quantum Science
  • Quantum Thermodynamics
  • Key Concepts of Theoretical Physics
  • Foundations of Quantum Mechanics
  • Quantum Information Theory
  • Machine Learning
Chau Nguyen

PD Dr. Chau Nguyen

Temporary Academic Councillor
Personal profile photo

Ph.D. Ismaël Septembre

Research assistant
Giulio Gasbarri

Dr. Giulio Gasbarri

Research assistant
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Dr. Raphael Mothe

Humboldt Research Fellow (Postdoc)
Kenneth Goodenough

Kenneth Goodenough

Scholarship holder (AvH Scholarship)
Lisa Weinbrenner

Lisa Teresa Weinbrenner

Doctoral candidate
Siyuan Qi

Siyuan Qi

Doctoral candidate

Our publications

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Journal article
2016

Generalized effective operator formalism for decaying systems

Journal article
2016

Steering Maps and Their Application to Dimension-Bounded Steering

Journal article
2015

Stochastic extensions of the regularized Schrödinger-Newton equation

Journal article
2015

Evaluating convex roof entanglement measures

Journal article
2015

Systematic errors in current quantum state tomography tools

Journal article
2015

Cavity-Assisted Manipulation of Freely Rotating Silicon Nanorods in High Vacuum

Journal article
2015

Quantum Nondemolition Measurement Enables Macroscopic Leggett-Garg Tests

Journal article
2015

Nonclassicality tests and entanglement witnesses for macroscopic mechanical superposition states

Journal article
2015

Coherence in the presence of absorption and heating in a molecule interferometer

Journal article
2015

Contextuality in phase space

Journal article
2015

Relaxations of separability in multipartite systems: Semidefinite programs, witnesses and volumes

Journal article
2015

Erratum: Coherence in the presence of absorption and heating in a molecule interferometer

Postal address

University of Siegen
Department of Physics
Emmy-Noether-Campus
Walter-Flex-Straße 3
57072 Siegen
Germany

Visitor address

University of Siegen
Department of Physics
Emmy-Noether-Campus, Room B-107
Walter-Flex-Straße 3
57072 Siegen
Germany

Secretariat

You can find the contact details of the group members in the team overview.