Current research projects
Towards Photonic Non-Abelian Quantum Gates
Funding Agency: DFG
Budget: 247,350€
Summary: Quantum information science, a field that has emerged over the past several decades, addresses the question of whether harnessing quantum mechanical effects through storing, processing and transmitting information encoded in inherently quantum mechanical systems can lead to new phenomena, functionalities, and devices. Quantum information is both fundamental science and a progenitor for new technologies. Photonic quantum systems provide many advantages, reaching from low levels of decoherence to precise single-particle quantum control and being mobile. Laser-written integrated photonic waveguides provide the unique capability of designing complex, stable quantum information circuitry with unprecedented flexibility. For example, non-Abelian geometric phases associated with non-Abelian synthetic gauge fields have recently been successfully implemented. Such phases are crucial for topological quantum computation, non-Abelian anyon statistics, and the quantum simulation of Yang–Mills theories. The aim of our proposal is to promote the implementation of photonic non-Abelian U(N) holonomies in integrated waveguide architectures with the vision to establish a basis for new quantum information processing applications in the framework of noisy intermediate-scale quantum (NISQ) processing. In particular, in the proposed project we will (1) develop the theoretical foundations for and experimentally demonstrate a U(3) holonomy using two indistinguishable photons and a network of four coupled sites, in which the waveguides’ bending geometry has been optimized, (2) develop and demonstrate a conceptual and experimental framework to include non-orthogonal modes and non-adiabatic quantum state evolution in the functionality of our integrated waveguide circuits which will allow us to access larger degenerate subspaces, including a U(4)-holonomy for two photons, and (3) implement various holonomic quantum gates and experimentally demonstrate holonomic quantum computation protocols. The strength of our proposal comes from combining two very fruitful modern research directions: multi-photon-state manipulation and integrated optical circuitry in order to explore fundamental concepts of quantum information processing, for the advancement of fundamental science as well as photonic applications.
Integrating 2D crystals and waveguide circuits: Active components and versatile exciton spectroscopy (LIMATI W02)
Funding Agency: DFG, Collaborative Research Centres
Budget: 890,400€
Summary: Project W02 is focused on the exploration of previously inaccessible features of the unique excitonic properties of transition-metal dichalcogenides (TMDCs) by establishing tailored near-surface interactions between TMDCs and laser-written freeform optical pathways within a carrier chip. The fundamental insights and technological advances developed in the process will allow us to incorporate TMDC-augmented waveguides and characterize their enhanced optical nonlinearity, as well as the non-Hermitian dynamics mediated by their absorption and optical gain. Our project intends to pave the way towards harnessing two-dimensional materials as functional elements in a new class of advanced photonic circuitry.
Imaging topological phases of laser-driven few- and many-particle systems (LIMATI W01)
Funding Agency: DFG, Collaborative Research Centres
Budget: 534,400€
Summary: In project W01, we address fundamental questions of topological features in quantum systems and photonics for strongly driven, interacting many-particle systems, as they occur in intense laser-matter interactions. With our combined theoretical and experimental efforts, we will address how topological invariants can be properly defined in nonlinear systems, and what the shapes and characteristics of topological edge states in interacting or nonlinear systems are. Further, we will investigate how topological invariants and the associated topological features behave under dimensional mapping. With our findings we will pave the way to experimentally explore multi-electron dynamics using a photonic platform.
Imaging of quantum systems: photons, molecules and materials (IRTG)
Funding Agency: DFG
Summary: The International Research Training Group (Canadian and German IRTG Coordination and Organization Agency) combines the research areas of quantum optics, ultrafast electron dynamics and electronic coherence to develop innovative concepts in telecommunications and data and image processing. Quantum technology exploits quantum mechanical effects to store, process and transmit information. This leads to novel phenomena, concepts and functionalities.
Research Training Groups offer doctoral candidates the opportunity to pursue their doctorate at the highest professional level through a comprehensive research- and qualification program.
Nonlinear topological phenomena in photonic lattices
Funding Agency: Sino-German Centre for Science Promotion
Budget: 95,294€
Summary: Topological photonics has emerged as a new frontier of research in optics and photonics and attracted increasing attention recently. Topological states of light offer a novel way for robust transport of light without backscattering even in the presence of disorder or defects. So far, topological phenomena have been studied mainly in linear topological structures, drawing much analogy from concepts developed in solid-state systems. However, rich fundamental phenomena are expected due to the interplay between nonlinearity and topology, which are difficult or even inaccessible in electronic systems. In this joint project, we study nonlinear topological phenomena in periodic structures based on the platform of photonic lattices. We explore nonlinearity-induced topological phase transition, topologically protected nonlinear edge states (solitons) and their interactions, and nonlinear topological phenomena in photonic lattices mediated by parity-time symmetry.
Electronic-photonic integrated quantum simulator platform (EPIQUS)
Funding agency: European Union
Budget: 325,000€
Summary: The aim of this project is to establish a cornerstone technology capable of simulating quantum mechanical problems in a compact device operating at ambient temperatures. To this end, we will develop a 3D-integrated quantum simulator, where a reconfigurable photonic quantum interference circuit, the entangled photon sources, and the qubit state preparation stage are monolithically integrated together with arrays of single-photon detectors. From this system, a quantum software will extract and process the quantum simulation results from the hardware. The consortium is comprised of several groups from across Europe with diverse expertise, ranging from material, device and circuit engineering to microfabrication technology, quantum optics, spectroscopy, and information technologies.
Non-Markovian Quantum Random Walks
Funding agency: German Research Foundation
Budget: 220,000€
Summary: In quantum physics, environmental noise represents the most prominent adversary that precludes the generation, control, and preservation of fundamental properties such as coherence, entanglement, and quantum correlations. Indeed, the fragility of quantum coherence is one of the main impediments for the development of quantum-enhanced technologies. Clearly, identifying mechanisms to prevent or slow down decoherence effects in quantum systems is an issue of scientific and practical importance. The aim of this proposal is to investigate the behavior of multiple interacting particles traversing dynamically disordered quantum systems. Our studies will advance our understanding of the primary physical events occurring in quantum complex systems. In addition, our work will help to identify potential applications of decoherence to control photon encoded information and many-body quantum correlations. Importantly, our theoretical findings will always be tested experimentally within the context of integrated quantum photonics.
3D Quantum Random Walks in Laser-Written Waveguide Structures
Funding agency: German Research Foundation
Budget: 200,000€
Summary: The aim of our project is to promote the understanding and control of quantum random walks (QRWs) of correlated and entangled photons on various lattice geometries, with the vision to establish a basis for new, on-chip quantum simulation and computing applications. Gaining knowledge about fundamental aspects of quantum transport is essential to understand a variety of elaborate phenomenon in nature like for instance photosynthesis. Along these lines, by enhancing the QRW complexity to three-dimensional lattice geometries a whole new class of networks can be investigated.
Besides the possibility to simulate complicated quantum systems the implementation of quantum search algorithms becomes feasible, which will give a tremendous boost in the field of quantum computation. Since the complete project relies on waveguide lattices it benefits from the advantages of integrated quantum-optical devices. With the superior stability and robustness, it is possible to design quantum networks for photonic QRWs that are orders of magnitudes smaller than bulk-optical systems built on an optical table, that work with higher efficiency and fidelity, and that require much less resources for their implementation.
Alfried Krupp Research Prize
Funding agency: Alfried Krupp von Bohlen und Halbach Foundation
Budget: 1,000,000€
Summary: As one of the most prestigious and highly endowed German research prizes, the Alfried Krupp Research Prize is awarded annually since 1996 to young professors at German universities in the field of natural and engineering sciences. Its aim is to allow the laureate to further improve his working environment and to push forward their scientific work in research and education.
Multi-scale laser system for the synchronized generation of high-power ultra-short laser pulses and high repetition pulse trains
Funding agency: German Research Foundation and the state of Mecklenburg-Vorpommern
Budget: 500,000€
Summary: The intense pulses supplied by this custom laser system allow for the highly localized deposition of energy within the bulk of transparent materials, a key requirement for the inscription of three-dimensional freeform photonic waveguide structures. As “circuitry for light”, intricate ensembles of such waveguides will drive several cutting-edge fields of research in the Solid-State Optics Group, including the complex nonlinear spatiotemporal dynamics of solitons and “light bullets”. Channeled by photonic lattices, light can be used to switch, route and modulate optical signals without the need for conventional slow electronics. Along a different avenue of research, the laser system will shed light on the formation of laser-induced refractive index changes by means of rapid pump-probe measurements with closely synchronized high- and low-energy pulses. The insights gained here will be instrumental the optimization of the waveguide inscription process and its adaptation to a wider range of functional materials for a new generation of advanced integrated optical circuits.
Addressing quantum eigenstates in integrated photonic structures
Funding agency: German Research Foundation
Budget: 200,000€
Summary: The aim of this project is to promote the understanding and control of waveguide architectures for coherent information transfer with the vision to establish a basis for new quantum information processing applications. In particular, our research will address (1) Eigenstate formation and transmission in periodically driven lattice systems, (2) Tailored input state projection on system eigenstates, and (3) Transport studies of multi-photon states in lossy integrated optical networks. Therefore, the main goal of our proposal is to conceive, implement and test a new approach for quantum information transfer. We will exploit the quantum eigenstates of the on-chip waveguide structures that in principle can travel indefinitely without any distortion due to their stationary nature. Apart from revealing new and fundamental scientific knowledge, which is based on our sophisticated approach of combining quantum state manipulation and optical integrated circuitry, our results will have immediate technological significance. We will combine the experimental work with theoretical analysis, in order to explain our results thoroughly and optimize device performance.
Polarization-entangled two-photon source
Funding agency: European Union
Budget: 60,000€
Summary: The polarization-entangled two-photon source by OZ Optics enables the holistic characterization of the birefringence of laser-written waveguide systems. Future fields of applications of this quantum-light source will be the fine-tuning and tailoring of quantum-optical circuits and the development of novel sensor systems for properties of quantum light based on integrated-optical arrangements in combination with the now accessible entanglement of photons.
High-power whitelight source with tuneable polarization-maintaining fiber output
Funding agency: European Union
Budget: 60,000€
Summary: The fiber-coupled high-power white-light source by NKT is employed for the holistic characterization of the optical properties of laser-written waveguide systems with high spectral resolution and large bandwidth. As “circuitry for light”, functionalized waveguides constitute the building blocks of integrated photonic devices. In conjunction with precisely characterized laser-induced micro- and nanostructures for the local modification of the host material, they enable all degrees of freedom of photons to be harnessed for classical as well as quantum-optical applications on a chip.
High precision positioning system for micro machining
Funding agency: European Union
Budget: 53,000€
Summary: The acquisition of a novel high precision positioning system has the ultimate goal of establishing new research directions within the field of optical micro machining using ultrashort laser pulses at the Institute of Physics. With the purchased apparatus, we are able to position a sample with nanometer precision with respect to an ultrashort pulse laser beam, which is vital for high precision modification of the sample material. A particular application of such high-precision material modifications is the fabrication of complex three-dimensional photonic waveguide structures in transparent bulk media. As “wires for light,” these devices constitute a fundamental component of integrated optical circuits. In combination with precisely tailored and positioned laser-induced micro- and nanostructures multiple degrees of freedom of photons are accessible for classical and quantum applications.
Quantum Simulators – from Atomic to Photonic
Funding agency: German Research Foundation
Budget: 420,000€
Summary: The central theme of this project is the use of quantum simulators for the realization of ‘topological physics’ that would be difficult or impossible to implement otherwise. One example is the realization of the ‘Topological Anderson Insulator’ - a system that has quantized edge conductance when disorder is increased. We aim to explore this system and demonstrate the first “Topological Anderson Insulator”. Likewise, we plan to explore and demonstrate non-Hermitian parity-time (PT) symmetric topologically protected states – which are currently believed to be impossible. In yet another direction, we will investigate wave dynamics in systems emulating relativistic phenomena, going far beyond current experiments: light waves and ultracold atoms displaying highenergy effects such as Klein tunneling, and redshift/blueshift together with tidal forces at the vicinity of massive gravitational objects. In a many-body setting, proximity to a quantum critical point will allow us to observe relativistic ‘Higgs’ like modes in variable dimensions. The quantum simulators described in this proposal have the capacity to realize physics that would be impossible otherwise.
Completed Projects
Error-Proof Bell-State Analyser (ErBeStA)
Funding agency: European Union
Budget: 270,000€
Summary: During this project, we will address the long-standing challenge of realizing a complete Bell-state analyser that is impervious to measurement errors. The implementation of such an error-proof Bell-state analyser constitutes an important milestone for information technologies as it forms the key component for universal optical quantum computers and long-distance quantum communication. Reliable Bell-state detection will immediately impact the development of emerging quantum technologies, facilitate high-precision time-keeping and sensing, and enable future technologies such as secure communication or quantum cloud computing. This major conceptual and technological advancement will be made possible by combining two of the most recent breakthroughs at the frontier of quantum optics and nanophotonics: (i) ultra-strong quantum optical nonlinearities obtained from Rydberg-atom interactions or from a single quantum emitter strongly coupled to an optical microresonator and (ii) nanofabricated optical waveguide chips that permit high-level control of light propagation at the wavelength scale. Building the proposed Bell-state analyser will involve the development of advanced optical devices such as nondestructive photon-number-resolving detectors as well as configurable photon-number-specific filters and sorters, all of which constitute major scientific and technological breakthroughs on their own.
Nonlinear Photonic Topological Insulators (NoPhToI)
Funding agency: German Research Foundation
Budget: 200,000€
Summary: The aim of this project is to promote the understanding of new physical phenomena in disordered photonic topological materials by using coupled optical waveguide systems. In particular, our theoretical and experimental research will address (1) Studies of topological nonlinear modes; (2) studies of novel lattice structures, in particular Lieb- and Kagome geometries; (3) Studies of nonlinear wave dynamics in topological media with PT-symmetric lattice structure. Apart from revealing new and fundamental scientific knowledge, which is based on our sophisticated approach of using a highly controllable optical system (i.e., arrays of evanescently coupled waveguides), our results will have immediate technological significance, as they can be used in telecommunication and photonic data processing. We will take advantage of the unique capabilities of our fabrication technology that allows us to directly address numerous physical questions. The synergies of our experimental work and theoretical analysis will serve to optimize device performance.
Radially Accelerating Light Waves (RALW)
Funding agency: German Research Foundation
Budget: 200,000€
Summary: It is the aim of this project to deepen the knowledge on so called Radially Self-Accelerating Beams (RABs). Our studies will involve theoretical as well as experimental aspects in order to enrich this flourishing field of research. In particular, we are going to answer the following questions: (1) How do the physical beam properties change under strong focusing conditions? (2) How can RABs be efficiently synthesized? (3) Do numerical methods allow for versatile beam tailoring in order to achieve specific spatial intensity distributions? (4) What are the advantages for laser material processing, especially in regards to laser drilling and photo lithography? (5) How can RABs be employed for the complex manipulation of nano-particles and even living cells?
Multipath Interference Tests in Quantum Mechanics
Funding agency: German Research Foundation
Budget: 200,000€
Summary: One of the key features of quantum mechanics is interference: if a particle can follow multiple paths towards a destination, all of these possibilities need to be taken into account to determine the chance of it ending up at the destination. However, this interference only considers all possible combinations of pairs of paths, but not three or more at a time. Our experiments using modern optical waveguide technology will test very precisely whether particles of light actually behave as quantum mechanics predicts, or whether there are deviations. At the same time, we will explore theoretically how alternative theories could look like and how their predictions could be tested.
Light Propagation in Locally Symmetric Waveguide Arrays
Funding agency: German Research Foundation
Budget: 200,000€
Summary: In a close collaboration between theory and experiment in this project a new class of systems will be explored, which consist of units with different local symmetries. The aim of this research is the systematic study of optical-wave mechanical properties of locally symmetric materials with the ultimate goal of developing a deep understanding of wave evolution in those systems. This includes a new form of controlling light localization due to local symmetries, and the design and construction of perfectly transmitting resonances in fully locally symmetric waveguide structures.
JIVE
Funding agency: German Ministry of Science and Education
Budget: 80,000€
Summary: The mission of JIVE is to develop a R&D network based on a strong High-Tech platform for fabrication and functionalization of optical sensors, which provides efficient communication channels for the transfer of knowledge. This allows viable international connections along the value-added chain, which by itself fosters and supports the transfer of technology between partners from industry and end users of sensor technology. Therefore, this project will have significant social impact such that people, their health as well as their environment will benefit in a sustainable manner. The main scientific and technological goal of JIVE is the development of novel technology approaches that can ultimately be transferred in enhanced optical sensors. To this end, the realization of photonic structures with dimensions across several orders of magnitude (100nm – 10cm) is of central importance. This will allow sensors that perfectly adapt to the conditions of applications with a particularly high demand on accuracy and manageability. Such applications are particularly important in the field of non-invasive diagnostics (e.g., cardiology, pneumonology, ophthalmology), for the detection of noxious substances in air and water, or for the characterization of biomedical compounds in pharmacological industry.
Optical transitions in photonic lattices
Funding agency: German Academic Exchange Service
Budget: 7,000€
Summary: This project focuses on the design and the fabrication of different linear photonic lattices with flat bands in their dispersion relation. Our main aim is to explore the dependence of different optical transitions in the system on both the fabrication parameters and the parameters of system itself. During the first year of the project, we shall work on optical transitions in photonic lattices with alternating couplings whereas in the concluding project’s year we are going to examine light dynamics in lattices with more than one flat band in the bandgap diagram.
Photonic circuits for deterministic photon sources based on 2D materials
Funding agency: German Academic Exchange Service
Budget: 16,000€
Summary: This project will develop an approach to perform complete quantum tomography of a deterministic photon source on a chip. Our preliminary work indicates that this method will be stable, fast and scalable, allowing rapid characterization of the quality of photon sources and facilitating scaling to multi-photon states. Then we will extend this approach to the 2D-material-based deterministic generation of photon states entangled in time and space. The final step will be on-chip manipulation of complex entangled states and their applications to biological sensing and quantum communication.
PhoToMaD
Title: Photonic Topological Materials with Disorder (PhoToMaD)
Funding agency: German Research Foundation
Budget: 200,000€
Summary: The aim of this proposal is to promote the understanding of new physical phenomena in disordered photonic topological materials, by using coupled optical waveguide systems. In particular, our theoretical and experimental research will address (1) Studies of topologically protected edge transport in disordered media with broken time reversal symmetry (i.e., a topological Anderson insulator); (2) Studies of edge and bulk transport in disordered non-Hermitian topological media; (3) Studies of nonlinear wave dynamics in disordered topological media.
E-GRAS
Title: Emulation of the Graphene Structure using Photonics (E-GRAS)
Funding agency: German Research Foundation
Budget: 200,000€
Summary: In this project, we emulate the physics of graphene using optical waveguide arrays that are arranged in honeycomb geometry. Since the paraxial wave equation, which describes the propagation of light through the waveguide array, is mathematically equivalent to the Schrödinger equation, describing the time-evolution of electrons in graphene, the dynamics of a propagating light wave in a periodic refractive index modulation (a waveguide array) is similar to the evolution of an electronic wave function in the crystalline potential of a solid. This allows us to exploit the impact of strain and disorder on the graphene structure, to probing new states inaccessible to conventional graphene, and to control the existence of these states in the fabricated structures.
PICQUE
Title: Photonic Integrated Compound Quantum Encoding (PICQUE)
Funding agency: European Union
Budget: 250,000€
Summary: This Initial Training Network is at the core of European technological innovation. Excellence in science is guaranteed by the involvement of world-leading groups which founded this research area. All the fundamental components of a photonic quantum processor will be addressed: generation, manipulation and detection of photon states. Particular attention will be devoted to potential applications and on how to interface all the different components. We will establish a world-class training platform spreading around the highly interdisciplinary and multisectorial European-led area of quantum integrated photonics. By driving the development of quantum optical technologies we foresee results of interest also for conventional optical technologies. The mission of PICQUE is to shape the new generation of quantum information scientists and empower them to engage in fruitful interactions with the industry.
Nonlinear Circuits
Title: Integrated Nonlinear Circuits for Broadband Quantum Optics
Funding agency: German Academic Exchange Service
Budget: 12,000€
Summary: This project will develop and demonstrate photonic devices for integrated generation, shaping, and routing of quantum states of light, based on ultrafast nonlinear optical interactions. Manipulation of photons entangled across a broad range of optical wavelengths will be achieved. This project will take advantage of complementary expertise of Australian and German partners in advanced fabrication technologies and their applications in photonic circuit development. The results of this work will open new opportunities for the use of non-classical photon states in the areas of information and communication, as well as imaging and sensing at extremely low-light few-photon levels for biological and security-related applications.
Enlightning New States of Matter
Titel: Enlightning New States of Matter
Funding agency: Thuringian Ministry for Economy, Science and Digital Society
Budget: 100,000€
Summary: In this project, the formation of a new state of matter based on crystalline phases in ferminonic condensates was investigated using lattices of evanescently coupled waveguides. Using a particular arrangement of the waveguides allows the emulation of the famous Gross-Neveu model, which in turn is the basis for the analysis of new fermonic states of matter.
Diamond Optics
Title: Diamond-/Carbon Based Optical Systems
Funding agency: German Ministry for Education and Research
Budget: 4,500,000€
Summary: The work within the research project was aimed at the fundamental understanding of the propagation of optical waves in different systems, whose material parameter and structure are based on the different macroscopic manifestations of carbon. The main motivation was to evaluate organic and inorganic carbon-based and -inspired optical materials as alternatives to the conventional silicon-based integrated optics dominating today and to harness them for innovative applications in optical micro- and nanotechnology.
Guided Light
Title: Defect-free Confinement of Light Waves
Funding agency: German Research Foundation
Budget: 400,000€
Summary: This project within the German‐Canadian Research Training Group „Guided light – Tightly packed“ aims at understanding novel mechanisms for advanced light confinement will be studied, in theory and experiment, using classical and quantum light. The basis for all implementations will be arrays of evanescently coupled waveguides, which are one of the most prominent model systems for advanced physics concepts. In particular, they allow the extension of the investigated concepts from the Hermitian into the non-Hermitian domain, opening the gate to unravel further novel and unexpected phenomena.
Luminous Flow
Title: Luminous Fluid Flow in 2d Structures: Experiment and Theory
Funding agency: German-Israeli Research Foundation
Budget: 200,000€
Summary: The goals of this research is the further development of analytical and numerical approaches for analysis of photonic flow equations, including proper consideration of quantum potentials and genuine quantum effects, applications of novel fabrication methods for complex waveguide structures, and experimental studies of a luminous liquid flow. This holds the promise of better insight into basic physical phenomena, from tunneling to "sonic" event horizons.
Quilmi
Title: Quantum Integrated Light and Matter Interfaceory (QuILMI)
Funding agency: European Union
Budget: 100,000€
Summary: In this project, we developed a new technology for interfacing atoms with light that is based on holes intersecting on-chip laser-written waveguides. These photonic cavities are created by ultrashort laser pulses – a technique which is completely novel. We have demonstrated our ability to realise cavities of arbitrary shape and to drill holes through the entire photonic chip, which will be eventually used to store the atom molasses on the chip. Moreover, we demonstrated that these holes can also be used for connecting photonic fibres with the chip, to ensure a stable setup in the vacuum chamber.
Space Time
Title: Correlated Photons in Integrated Optical Structures
Funding agency: Thuringian Ministry for Education, Science amd Culture
Budget: 110,000€
Summary: This project within the frame work of the collaborative research group „Space Time“ aims at understanding fundamental processes in the evolution of correlated photons in lattices of evanescently coupled waveguides. A focus of this project was the fabrication and characterization of systems with two transverse spatial dimensions that allowed us to investigate new features based on the dimensionality of quantum random walks.