Bottom-up design and exploration of p-electron quantum magnetism

In recent years, new surface chemistry methods have enabled the fabrication of graphene nanostructures, so-called nanographenes, which is not possible via classical solution chemistry or 'top-down' structuring of graphene layers. Meanwhile, the atomic precision achieved in these molecule-based 'bottom-up' processes allows the fabrication of a variety of different shapes of these pure carbon structures - and thus the ability to selectively choose the electronic properties. The latest breakthrough in this field now even makes it possible to produce magnetic nanographenes.

The main goal of our project is to fabricate magnetic nanographenes in which multiple magnetic moments are coupled together in a controlled manner. The atomic precision of the 'bottom-up' strategy will be used to chemically control this coupling and thus realize complex quantum states that can provide the basis for future quantum computers. To provide the necessary expertise in synthesis, characterization, and modeling, we have assembled a highly interdisciplinary consortium with backgrounds in organic chemistry, surface chemistry and physics, electron spin resonance, and theoretical physics. The proposed investigation methods are capable of resolving single molecules and even single spins, allowing direct relationships to be established between atomic structure, its modeled properties, and experimentally determined magnetic and electronic properties. Important milestones of the project are the elaboration of a fundamental understanding of magnetic moments induced via molecular orbitals and the development of new methods for the combined solution and surface synthesis of complex magnetic nanostructures.
Current quantum computers show us the potential that can be unlocked with 'qubits' based information technology. Currently, however, the quantum states required for this can only be realized at very low temperatures in the millikelvin (mK) range. An important reason for this is their sensitivity to environmental influences, which severely limits their lifetime. The use of carbon has important advantages in this respect due to its low atomic number. The 'PiMag' project will systematically explore this potential. Thus, via measurements on individual spins, we will be able to measure the exact lifetime of nanograph-based quantum states. This will allow an accurate evaluation of the required environmental conditions under which the predicted long lifetime of carbon-based quantum states can actually be put into practice. Together with the chemically controlled coupling of different quantum states, we will thus establish fundamentals that show to what extent nanograph-based materials can be used for the generation of long-lived quantum states in quantum computing.