Space-Time Quantum Information from the Entangled States of Magnetic Molecules
W. Ho, University of California, Irvine (Principal Investigator)
W. J. Evans, University of California, Irvine (Co-Investigator)
R. Wu, University of California, Irvine (Co-Investigator)
The speed and capacity for information storage and processing can be greatly enhanced by tapping into the quantum properties of the system. This collaborative project combines synthesis, measurement, and theory of magnetic molecules as qubits by studying the energies of quantized excitations, the length of time the quantum states remain superposed and entangled, and the different factors that degrade their quantum behavior. Unlike the discrete and deterministic states in the classical binary 0 or 1 bit, the superposition of the two-level spin states of magnetic molecules and their quantum correlation give rise to a vast number of probabilistic states that can be tapped for quantum information processing. In this research, the magnetic excitations in molecular systems, from a single molecule to molecular lattices, are measured by inelastic electron tunneling spectroscopy with the scanning tunneling microscope (STM). The superposition and entanglement of the magnetic states are created and tracked in time by terahertz (THz) laser pulses of femtosecond duration coupled with the STM. Measurement with simultaneous spatial and temporal resolution enables a basic understanding and system control at the atomic scale. A variety of molecular complexes that have a magnetic atom sandwiched between two rings of carbon atoms will be synthesized, measured, and calculated. The two rings isolate the central magnetic atom from its environment, which would increase the length of time the spin quantum states remain superposed and entangled. An important goal of the planned research is to maximize this time for information processing based on the quantum states by optimizing the composition and structure of molecules. The sandwiched metal atom in these molecules can be a transition metal, a rare earth metal, or uranium to provide rich spin correlation effects. The possibility of ligand substitution allows alterations of the molecular motions that affect the strength of the spin-vibrational coupling and the time duration of the spin coherence in molecular qubits. Reversible electron transfer from the STM tip to the bridging molecule in bimetallic rare-earth magnetic molecules allows electrical control of the spin correlation between the two magnetic atoms within the complex. This research lays the foundation for optimizing the composition, structure, and interaction of magnetic molecules as qubits for quantum computing and information storage through the combined efforts of chemical synthesis, space-time measurement, and ab-initio theory.
