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Experimental Quantum Optics Chair

Welcome to the Experimental Quantum Optics Chair of Prof. Dr. Ch. Wunderlich at the University of Siegen.

Our experimental and theoretical work concentrates on the development and exploration of new schemes for quantum information processing using individual atoms and open fundamental questions related to quantum physics.


Improving complex Computer Vision Tasks with Quantum Computers


Shape correspondence is a fundamental computer vision task in which vertices of 2D or 3D bodies are mapped to another. This represents a combinatorial optimization problem that takes a lot of time on classical computers. In the publication Q-Match: New approach for shape matching with Quantum Annealing our work group contributed to a new quantum computing approach, called Q-Match, to speed up this optimization problem.

ATIQ Project started: Implementation of quantum algorithms from chemistry and finance


Standorte der Quantencomputerforschung in NRW

In the project "Quantum Computers with Trapped Ions for Applications" (ATIQ), quantum computer demonstrators are being developed together with users. The 25 project partners are tackling major technical challenges in order to realize German quantum computer demonstrators and make them accessible to users in 24/7 operation. The leading groups in ion trap research at the universities in Hanover/Braunschweig, Siegen and Mainz have joined forces with other leading research institutions and industrial partners for this purpose. The project is funded by the Federal Ministry of Education and Research. ATIQ indeed holds enormous potential for economic and scientific success. Quantum computers promise unprecedented computing power for applications where purely digital classical high-performance computers alone fail completely. The combination of a classical high-performance computer and a quantum computer, on the other hand, opens up completely new possibilities. There is therefore an urgent need for Germany to provide robust and scalable quantum hardware. The ATIQ consortium aims at optimized hardware for applications in chemistry. Novel chemical substances and the reactions to produce them could then be simulated on quantum computers. Another use case is in finance, where completely new approaches are being taken in credit risk assessment. The core of the quantum processor in ATIQ is based on ion trap technology, which is seen worldwide as one of the most promising routes to quantum computing. However, current systems are still complex laboratory machines with significant maintenance and calibration required by highly skilled personnel. ATIQ addresses the technical challenges to achieve continuous operation with reliable high quality computing operations. To this end, the ATIQ partners, in cooperation with technology and industry partners, optimize the control of the processors with electronic and optical signals and thus aim to achieve high reliability and availability so that external users can independently execute computing algorithms. In addition, such optimization also promises to scale up the quantum demonstrators from an initial 10 to eventually more than 100 qubits. The strength of the consortium is based on its knowledge as a developer of ion trap technology and the physical and technical fundamentals at the participating universities and research institutions.

Further partners are: Leibniz-Universität Hannover, Johannes Gutenberg-Universität Mainz, TU Braunschweig, RWTH Aachen, Physikalisch-Technische Bundesanstalt and Fraunhofer-Gesellschaft.

The companies are: AMO GmbH, AKKA Industry Consulting GmbH, Black Semiconductor GmbH, eleQtron GmbH, FiberBridge Photonics GmbH, Infineon Technologies AG, JoS QUANTUM GmbH, LPKF Laser & Electronics AG, Parity Quantum Computing Germany GmbH, QUARTIQ GmbH, Qubig GmbH and TOPTICA Photonics AG.

Associated partners are: AQT Germany GmbH, Boehringer Ingelheim, Covestro AG, DLR-SI, Volkswagen AG and QUDORA Technologies GmbH.

Pioneers in Quantum Computing


Quantum Computing Research in NRW

The Frankfurter Allgemeine Sonntagszeitung reported in the article "Quantentechnologien in NRW" about the current research projects throughout NRW. At the University of Siegen, in the research group of Prof. Dr. Christof Wunderlich, the first German quantum computer was put into operation in 2010. It is based on the MAGIC (Magnetic Gradient Induced Coupling) principle, which allows to use commercial high frequency technology for qubit control. It also enables operations on individual qubits with unprecedented fidelity while minimizing crosstalk and providing high connectivity between qubits.

„Deterministic control of individual quantum systems is leading to a new paradigm in information processing.“ PROF. DR. CHRISTOF WUNDERLICH, UNIVERSITÄT SIEGEN

MAGIC quantum computer for industry and science: Start of research project MIQRO


The joint research project MIQRO between the University of Siegen, Leibniz Universität Hannover , Heinrich-Heine-Universität Düsseldorf, QUARTIQ GmbH and eleQtron GmbH as an associated partner is funded by the BMBF and is scheduled to run for 4 years. The quantum computer developed and operated in this project will be scalable to a thousand quantum bits, paving the way for diverse industrial and academic applications beyond the capabilities of classical supercomputers. The MIQRO project will develop a breakthrough modular quantum computer built from quantum kernels that use stored atomic ions as quantum bits. The quantum logic operations performed in these quantum kernels – equipped with unprecedented functionality – are controlled by radio frequency (RF) waves. This is made possible by Magnetic Gradient Induced Coupling (MAGIC). The MAGIC concept is distinguished from other approaches by perfectly reproducible qubits, greatly reduced cooling requirements, and integrable high-frequency electronics for controlling qubits. Moreover, the simultaneous coupling of many qubits in a quantum kernel, while maintaining unrivaled small crosstalk between qubits, will accelerate quantum algorithms. Here, the MAGIC method will be extended to include new high-performance, microstructured trapped ion memories. This will enable high-fidelity quantum gates and quantum logic error correction, thus contributing significantly to the scaling of quantum computers. The quantum kernel developed and operated in this project, represents the core of a future ion-based universal quantum computer. This quantum computer will be scalable to a thousand qubits, paving the way for a wide variety of industrial and academic applications that are unthinkable today.


Aus Quantenregistern bestehender Quantenkern, welcher sich zu Multi-QPU-Systemen für erste industrielle Anwendungen skalieren lässt. © MIQRO/eleQtron GmbH

Aus Quantenregistern bestehender Quantenkern, welcher sich zu Multi-QPU-Systemen für erste industrielle Anwendungen skalieren lässt. © MIQRO/eleQtron GmbH

Within this joint project, the expertise of the participating partners will be put to optimal use. For example, at the University of Siegen, the conceptual basis for the implementation of quantum logic operations envisaged here, MAGIC, was developed and demonstrated. Together with the Institute of Quantum Optics at Leibniz Universität Hannover, headed by Prof. Dr. Christian Ospelkaus, the chips will be specified and developed, extending the proven MAGIC method with new high-performance, micro-structured ion processors. This will make LUH's innovative microfabrication processes and experience with the production of several generations of ion traps fruitful for the collaborative project. With experts in the field of quantum state measurement and reconstruction, Heinrich Heine University Düsseldorf, with Prof. Dr. Martin Kliesch as theory partner, is ideally placed to develop and implement the necessary characterization and verification methods. For the electronic control systems, MIQRO builds on the leading developments of QUARTIQ GmbH led by Dr. Robert Jördens, whose control software platforms ARTIQ and Sinara are already used by research groups worldwide to control quantum technologies and cover a broad requirement profile with industrial-grade components.

Leibniz Universität Hannover - Fakultät für Mathematik und Physik - Institut für Quantenoptik, Hannover
Heinrich-Heine-Universität Düsseldorf - Quantum Technology, Düsseldorf
QUARTIQ GmbH, Berlin
eleQtron GmbH
BMBF Quantentechnologien
VDI-TZ Düsseldorf

Genuine temporal correlations can certify the quantum dimension


TemporalCorrelationsTemporal correlations in quantum mechanics are the origin of several non-classical phenomena, but they depend on the dimension of the underlying quantumsystem. This allows one to use such correlations for the certification of a minimal Hilbert space dimension. Here we provide a theoretical proposal and an experimental implementation of a device-independent dimension test, using temporal correlations observed on a single trapped 171Yb+ ion. Our test goes beyond the prepare-and-measure scheme of previous approaches, demonstrating the advantage of genuine temporal correlations.

Computational art with quantum tricks


From September 16 to 21, 2019, the highlights of physics in Bonn focused on how current physics research succeeds in making the invisible visible. The heart of the science festival under the motto "Show yourself" was an interactive exhibition on Münsterplatz. At each of the approximately 40 exhibits, scientists from Bonn and all over Germany were available for questions, explanations and discussions.  With our contribution "Rechenkunst mit Quantentricks" we were able to show the basics of a quantum computer based on stored ions in a generally understandable way. The live demonstration of a functioning Paul trap, named after the former Bonn Professor Wolfgang Paul, invited to lively discussions on the topic of quantum computing. There were also science shows, live experiments, the Einstein Slam, a junior lab, workshops, a competition for schoolchildren, numerous lectures and lots of science to touch and try out.

Engineering a Scalable Quantum Information Proccessor



The realization of a quantum computer requires interdisciplinary efforts in the field of basic research and engineering. That is why we organize a workshop in cooperation with Dr. Ing. Degenhardt from Forschungszentrum Jülich in the period from 23.04.19 to 26.04.19 in the Physikzentrum Bad Honnef.

Quantum computers, once available for widespread use, will revolutionize the ways we generate and use new knowledge – of fundamental scientific nature and for a wide range of applications. The quest for a scalable quantum computer is as of yet largely driven by experts in physics and in computer science. The challenges posed by this task, however, will necessarily require in addition dedicated and target-driven efforts in engineering. Vigorous innovative research and development in various fields of engineering will be pivotal for advancing successfully on the route towards a quantum computer, or quantum simulator, that is able of solving problems that, for all practical purposes, are intractable on classical computers. This workshop will bring together researchers already active at the forefront of this rapidly developing field, both from fundamental science and from engineering. It will put emphasis on implementations of quantum computing and quantum simulation using semiconductors, superconducting structures, and trapped atomic ions as physical systems.

Leaping into the future with quantum technologies


The CEO of the IT security company secunet AG, Rainer Baumgart, visited our group for the recent issue of their customer magazine "secuview". Together with Prof. Christof Wunderlich (Siegen) and Prof. Dieter Meschede (Bonn) he discussed current developments and the state of the art of quantum technologies in the context of IT security.
Issue 1|2018 of "secuview" features an article about the visit and the discussions.

"Quantum technology is currently one of the hottest topics in science and technology. In particular, the development of quantum computers is the subject of much discussion, and if these innovative computers one day become very powerful, cryptography once more will have to reinvent itself from the ground up. With quantum computers (among many other applications) threatening cryptographic processes which are commonplace today, the aim of research into quantum communication is to develop new, highly secure encryption methods. What many people do not know is that cutting-edge research on quantum technologies is taking place in the heart of Germany. secuview visited two of the most influential scientists in this field – Professor Dieter Meschede and Professor Christof Wunderlich – who are conducting fundamental research with very different objectives." - secuview 1|2018

Investigation of the anomalous heating of trapped ions


A major obstacle in the way of miniaturisation of ion traps, desired for many aspects of trapped ion quantum information processing, is anomalous heating. This is heating of the ion's motion via electric field fluctuations of the trap electrodes. These fluctuations are orders of magnitude stronger than expected from Johnson noise. The reason for that is mostly associated with surface contamination/oxidation, however the actual mechanism behind this phenomenon is not understood so far, hence the heating is called "anomalous".
One of the ways to shed light onto the anomalous heating mechanism is the study of the ion's heating rate dependence on the ion-electrode distance.
We have built a unique planar ion trap with tuneable ion-surface separation and measured this dependence directly for the first time. Our measurements yield a dependence in reasonable agreement with a power law of exponent -4 that is predicted by some theories.