Characterization of Multi-Qubit Molecular system using Scanning Tunneling Microscope (STM)

Abstract

Quantum computing exploits the coherent manipulation of quantum two level systems to perform computational tasks beyond the capabilities of classical computers. Among the various physical implementations of qubits, molecular spin systems have emerged as promising candidates due to their reproducibility, chemical tunability, and potential scalability. Furthermore, molecular qubits can be engineered to host one or multiple interacting spin centers with tailored magnetic properties, making them attractive platforms for quantum information processing. In order to design practical molecular quantum technologies, it is required first the ability to characterize individual molecules and then to be able to manipulate their quantum states with high spatial precision. Scanning tunneling microscopy (STM) provides atomic resolution imaging of molecules adsorbed on conductive surfaces, while electron spin resonance (ESR) provides coherent control of spin states through resonant microwave excitation. The combination of both techniques in ESR-STM has recently enabled coherent manipulation of individual atomic and molecular spins with spatial resolution of the other of ˚A, opening new opportunities for controlling single molecules. This thesis characterizes NiCu molecular spin qubits using STM techniques and performs the first step for designing practical molecular quantum technologies. These molecules constitute a chemically engineered multi-qubit platform in which coupled spin-1/2 states can be individually addressed and manipulated.