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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
2006

Energy and multipartite entanglement in multidimensional and frustrated spin models

Journal article
2006

Generalized spin-squeezing inequalities in N -qubit systems: Theory and experiment

Journal article
2005

Bell inequalities for graph states

Book chapter
2005

Entanglement of trapped ions

Book chapter
2005

Quantum Correlations as Basic Resource for Quantum Key Distribution

Journal article
2005

Detecting two-party quantum correlations in quantum-key-distribution protocols

Journal article
2005

Experimental analysis of a four-qubit photon cluster state

Journal article
2005

Detecting genuine multipartite entanglement with two local measurements

Conference paper
2005

Entanglement of trapped ions

Journal article
2005

Scalable multiparticle entanglement of trapped ions

Journal article
2005

Entanglement detection in the stabilizer formalism

Journal article
2005

Multipartite entanglement in spin chains

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.