Photogenerated molecular excited states and electron transfer reactions are beginning to play a major role in quantum information science (QIS). From the QIS perspective, a critical requirement for any physical qubit is preparation of a pure initial spin state. In addition, the preparation of two-qubit entangled states is necessary to execute fundamental quantum gate operations. Photoexcitation of a covalent organic donor-acceptor (D-A) molecule having a well-defined D-A distance and orientation can result in sub-nanosecond electron transfer to produce a spin-entangled radical ion pair (RP) having an initial pure singlet spin configuration. If the spin-spin exchange and dipolar interactions within the RP are weaker than the electron-nuclear hyperfine interactions, the initially pure singlet RP will coherently mix with its corresponding triplet states via the radical pair intersystem crossing mechanism to form a superposition state that can be used to implement a variety of QIS strategies. Time-resolved electron paramagnetic resonance (EPR) and pulse-EPR spectroscopy will be used to manipulate, control, and observe these coherent spin states. This project will address several goals based on what are known in the QIS field as the Di Vincenzo criteria, which are essential for exploiting the properties of multi-radical assemblies as spin qubits that target QIS applications: 1) generate a high fidelity entangled quantum state multiple spin qubits using hyperpolarization strategies; 2) determine the dephasing mechanisms within the spin qubit assemblies; 3) manipulate and address specific spin qubits to demonstrate quantum gates; 4) use both microwave and visible photon pulses to move (teleport) spin coherences between two sites; 5) establish strategies for scalable spin qubit arrays based on DNA hairpin structures.
|Effective start/end date||7/1/19 → 6/30/22|
- National Science Foundation (CHE-1900422)