Light Modulation of Charge Transfer-Induced Spin-Transfer Processes in Single Molecules for Quantum Information Science

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

In this project, funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Natia Frank of the Department of Chemistry at the University of Nevada-Reno is developing chemical complexes that change color on exposure to light (photochromic). These complexes also exhibit changes in magnetic properties with light. Functional materials that change magnetism, color or charge upon application of external stimuli (light, electric field, or magnetic field) are central to the development of non-volatile memory technologies for computers, spintronics devices, and sensors for quantum information science. The materials designed and developed in this research can be used as "qubits" in Quantum computing, communications, and sensors. In general, a qubit possesses at least two well-defined states that can be prepared and addressed independently. Qubits can interact with stimuli to generate an infinite number of intermediate states leading to exciting new possibilities for data processing, storage, and sensing at the quantum level. The immediate goal of this project is the creation of a generalized strategy for molecular qubits that can be controlled with light under ambient conditions to enable embedded resistive memory devices and sensors with significantly decreased energy demand. The research lies at the interface of chemistry, physics, and material science, providing multidisciplinary training to students in the STEM sciences. The research project will also serve as a platform for Community Engaged Learning and the development of modified teaching practices for increasing the success of diverse groups in the STEM fields. Community-engaged learning activities will involve research assistantships with structured mentoring activities for middle-school and high-school students and the development of new teaching strategies for diverse learners in the undergraduate classroom. The concept of coupling optically-bistable photochromic ligands to electronically-bistable metal complexes is a strategy for controlling the electronic structure and lifetime of optically-gated functional materials. Photochromic spirooxazine ligands have two electronic states that can be gated optically. When coupled to an electronically bistable cobalt semiquinone with two ground state electronic states, a four-state electronic system is generated. This coupling, a Photoisomerization Induced Spin Charge Excited State (PISCES) process, could lead to a powerful strategy for optically gating spin states. The electronic coupling between metal center and photochrome states, however, is complex, and fundamental studies towards elucidating the primary mechanism of electronic coupling are central to the expansion of this strategy towards other spin-based systems. This project will determine the fundamental electronic and structural factors that govern PISCES processes in a broad class of electronically bistable metal complexes that can serve as spin-qubits; evaluate the spin dynamics and decoherence times for optically-gated metal complexes to determine design principles for this class of spin-based qubits; and determine the effect of intermolecular interactions on PISCES processes, spin lifetimes and decoherence in nanostructured thin films and surfaces. The results of this project could provide fundamental insight into the electronic coupling parameters critical for the acceleration of low-energy demand sensor and computing applications based on quantum architectures. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.