Non-invasive imaging and high-fidelity coherent control of surface-supported spins

• Applicant: Dr. Aparajita Singha, Ph.D.
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 504973613

Controlling individual atoms and molecules at their native spatio-temporal limit has an indispensable appeal that has driven fundamental research for decades. Atomic-scale interactions and correlations are also the basis of all timeless technological progress, ranging from nanoelectronics to information processing. In particular, a new attractive avenue has recently emerged for nanoscale quantum bits made of individual lanthanide atoms and molecules. The intrinsic large magnetic moment, non-trivial intra- as well as inter-atomic electron correlations, and long-term quantum coherence in these model systems altogether offer a myriad of new exciting possibilities across molecular magnetism and quantum computing research. My present scientific effort is devoted to understand and control quantum mechanical properties of such smallest building blocks of matter, especially by probing them in the least invasive manner. However, addressing the spin states in such quantum systems is an extremely challenging task. So far, only scanning tunneling microscopy (STM) with subatomic spatial resolution is capable of achieving this, albeit being highly invasive and limited with the scope of operational temperature (<4 K). Atomic force microscopy (AFM) using novel defect centers in diamond (NV) has the potential to overcome these limitations, given their unparalleled magnetic sensing capability, high-fidelity optical readout, and broad operational range of temperature. However, this method currently suffers from insufficient resolving power (tens of nm) primarily due to fluorescence quenching in so-called shallow NV centers. By combining controlled surface-chemistry with AFM-based manipulation techniques, I aim to resolve this in order to achieve highly sensitive and yet non-invasive access and quantum control at the atomic scale. The proposed programme is designed to surpass the current capabilities of STM in this context, while simultaneously generalizing the scopes of scanning NV-magnetometry for addressing solid-state spin systems. Through this programme I will target atomic-scale quantum architectures made of lanthanide single spins either adsorbed or embedded as artificial 2D lattice, for approaching room-temperature stable qubit arrays.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: First UHV sample manipulator, one for each setup ; Second UHV sample manipulator, one for each setup
• Instrumentation Group: 8180 Vakuumbauteile, Rezipienten, Dampfsperren