(A)diabatic passages in solids for nuclear hyperpolarization and optimization on the model system nitrogen-vacancy centers in diamond

• Applicant: Dr. Ralf Wunderlich
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 510693845

The aim of the project is to investigate the transfer of non-Bolzmann distributed electron spin polarization to nuclear spins. The basic idea is to exploit diabatic and adiabatic passages in the eigenstates of the electron-nucleus systems. A parameter (e.g. an external magnetic field or an externally irradiated microwave field) is continuously changed in time. The chosen time course determines the efficiency with which a potential polarization transfer between the system constituents occurs. The question will be investigated in combination with a compact and inexpensive benchtop NMR device. These devices offer a comparatively weak (by NMR standards) magnetic field of about three Tesla. This results in a lower NMR signal compared to large superconducting NMR magnets. Nuclear hyperpolarization methods can potentially compensate for this signal difference. Nitrogen-vacancy centers (NV centers for short) in diamond will be used as a model system. Their electron spins can be highly polarized by optical illumination. The challenge is now to transfer this polarization to surrounding nuclei (13C spins in the diamond model system). This involves hyperpolarizing the solid sample in a very low magnetic field (a few millitesla) in a so-called "hyperpolarizer" under optical illumination and then transferring it to the benchtop NMR instrument. For the electron-nucleus spin transfer different methods can be considered, but here the (a)diabatic passages will be used. Exploitation of this technique could in the future increase the signals in NMR applications by orders of magnitude and thus reduce measurement times and costs. Furthermore, the electrons and nuclei involved can be considered as qubits and the polarization transfer as a gate operation between them. Thus, understanding the underlying quantum mechanical processes of hyperpolarization is equally relevant for quantum information processing (QIP). The focus will be on direct nuclear hyperpolarization application, but relevance will always be considered in QIP.

• DFG Programme: Research Grants
• Major Instrumentation: Tisch-NMR-Gerät
• Instrumentation Group: 1740 Hochauflösende NMR-Spektrometer
• Co-Investigator: Dr. Wolfgang Knolle