Highly defined 2D arrays of surface-decoupled molecular qubits

• Applicants: Professorin Dr. Anke Krüger; Professor Dr. Joris van Slageren
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569330862

Quantum technologies have been at the center of scientific and societal attention for some time now. Current systems for quantum technologies have a number of limitations with regard to the required properties, depending on the system selected. For example, the properties, in particular the energy levels, of available material classes such as superconducting qubits, color centers in diamond or donors in phosphorus can only be adjusted to a very limited extent. The positioning and arrangement of a larger number of qubits is also impossible or very difficult. Molecular systems offer a number of advantages here, such as long coherence times and electrical or optical readout at single-particle level. Through targeted synthesis, qubits with precisely adjustable energy levels can be obtained and a defined surface connection or linkage to larger arrangements can be achieved through derivatization. The aim of this project is to exploit the curved, highly symmetric structure of tribenzotriquinacene (TBTQ) to create highly defined arrays of molecular quantum bits (MQBs) on surfaces and to study their quantum properties. Tribenzotriquinacene has a highly curved triquinacene core that is triply benzannulated. This results in the strongly curved, C3-symmetric structure of this hydrocarbon. Due to this structure, TBTQ has a number of advantageous properties, among them the disruption of π-conjugation in the sp3-hybridized dome of the convex molecule and the rigid, highly symmetric structure, which enables the formation of defined two-dimensional lattices. In this project, we propose to synthesize and study tailored, qubit-functionalized TBTQ conjugates and to apply them to form self-assembled arrangements on different substrates. The building blocks and their 2D-assemblies will be investigated with regard to their quantum properties and the quantum spin dynamics will be characterized using pulsed electron spin resonance spectroscopy The modular approach of this project aims at the investigation of a range of MQB-TBTQ conjugates and the optimization of their assembly and qubit properties. This paves the way for the application of two-dimensional molecular assemblies in quantum technology.

• DFG Programme: Research Grants