Our Research Topics
Our research focuses on fundamental research and experimental investigations in quantum science, as well as the development of advanced photonic quantum technology for applications in quantum information processing. The fact that photons have an intrinsic lack of decoherence and can be conveniently manipulated with high precision, makes them attractive for many applications. The photons’ inherent advantage of being mobile provides a unique opportunity of transmitting and processing quantum information by using the same physical system.
Quantum Cryptography
We investigate how the laws of quantum theory can boost the security of modern cryptography, from secure computation to secure communication. By carefully designing quantum-cryptographic primitives, proving their security in the ideal and photonic settings, and mapping them onto state-of-the-art photonic platforms, we experimentally demonstrate new applications, ranging from blind quantum computation to quantum-digital payments, quantum leader election, limited-knowledge proofs and secure multiparty computation.
Quantum Foundations
Quantum foundations explores the fundamental principles of quantum mechanics, and as such underpins modern quantum technologies. It is a broad and = interdisciplinary field, building on concepts from quantum information, quantum communication, quantum computing and fundamental quantum optics. Our group investigates a wide array of these foundational topics using table-top photonic experiments. Our research spans topics from quantum thermodynamics to the development of new techniques to generate and characterize complex entangled states.
Quantum - Gravity Interface
We investigate the influence of Earth's gravitational field on the quantum interference of entangled photons. Our research advances precision optical fiber interferometry to detect the minute gravitational phase shifts acquired by maximally path-entangled quantum states propagating along trajectories separated by laboratory-scale height differences, providing a platform for probing the interplay between quantum mechanics and gravity.
Photonic Quantum Computing
Photonics is a leading platform for quantum computing, combining high-fidelity control of quantum states with scalable integration. Integrated photonics enables compact, stable processors, while advances in single-photon sources and detectors are moving the field toward fault-tolerant operation.
Our group investigates the hardware and computational building blocks of scalable photonic quantum technologies. Using state-of-the-art single-photon sources, time-bin architectures and programmable photonic circuits, we implement adaptive protocols, including quantum machine learning algorithms. A central question in our research is where quantum resources benefit information processing. We study how interference and entanglement can enhance computation and address tasks that may be hard for classical approaches. We also generate and characterize large multipartite entangled states, such as GHZ and cluster states, which are key resources for measurement-based quantum computing.
Nonlinear Nanophotonics
Nonlinear optics is a fundamental resource for quantum technologies, enabling essential operations like the generation of entangled photon pairs. While traditional bulk crystals require strict phase-matching that tightly constrains device design, scaling materials down to the ultimate thickness limit unlocks a highly flexible, phase-matching-free regime. This freedom allows us to engineer quantum sources without the rigid geometric and dispersive limitations of conventional optics. Our group investigates ultra-thin media and 2D materials to develop scalable nanophotonic quantum hardware. Because identifying the right physical platform is critical, we utilize classical nonlinear optical measurements to rapidly characterize and discover new materials that exhibit exceptionally strong nonlinearities.
Impressions from our labs
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Valeria Saggio -
Solvejg Skalvy -
Der Knopfdrücker -
Solvejg Skalvy -
Solvejg Skalvy -
Peter Schiansky
The Walther Group on Screen
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