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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
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Ph.D. Ismaël Septembre

Research assistant
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Dr. Giulio Gasbarri

Wissenschaftliche*r Mitarbeiter*in
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Dr. Raphael Mothe

Humboldt Research Fellow (Postdoc)
Kenneth Goodenough

Kenneth Goodenough

Scholarship holder (AvH Scholarship)
Albert Rico

Albert Rico

Wissenschaftliche*r Mitarbeiter*in
Lisa Weinbrenner

Lisa Teresa Weinbrenner

Doctoral candidate
Siyuan Qi

Siyuan Qi

Doctoral candidate
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Adam Fredriksson

Doktorand*in

Our publications

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Journal article
2008

Mermin inequalities for perfect correlations

Journal article
2008

Low energy properties of even-legged d-dimensional quantum spin systems: A variational approach

Conference paper
2008

Quantum computation with trapped ions

Journal article
2008

Theory of near-field matter-wave interference beyond the eikonal approximation

Journal article
2008

Generalized Ardehali-Bell inequalities for graph states

Journal article
2008

Multiparticle entanglement under the influence of decoherence

Journal article
2008

Lower bounds on entanglement measures from incomplete information

Journal article
2008

Unifying several separability conditions using the covariance matrix criterion

Journal article
2008

Absolute absorption spectroscopy based on molecule interferometry

Journal article
2007

Experimental entanglement of six photons in graph states

Journal article
2007

Toolbox for entanglement detection and fidelity estimation

Journal article
2007

Covariance matrices and the separability problem

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.