CASTLE · Chirality and spin selectivity in electron transfer processes: from quantum detection to quantum enabled technologies

Chirality is a key property of molecules important in many chemical and nearly all biological processes. Recent observations have shown that electron transport through chiral molecules attached to solid electrodes can induce high spin polarization even at room temperature. Electrons with their spin aligned parallel or antiparallel to the electron transfer displacement vector are preferentially transmitted depending on the chirality of the molecular system resulting in Chirality-Induced Spin Selectivity (CISS). The long-term vision of the CASTLE project is to transform the CISS effect into an enabling technology for quantum applications. This will be accomplished by achieving four key objectives. 1) The occurrence of CISS will be studied at the intramolecular level by photo-inducing rapid electron transfer within covalent donor-chiral spacer-acceptor molecules to generate long-lived radical pairs (RPs). 2) Direct detection of RP spin polarization will be performed using time-resolved and pulsed electron and nuclear magnetic resonance techniques. In addition, polarization transfer from one of the radicals comprising the spin-polarized RP to a stable molecular spin (Q) will be used to initialize the quantum state of Q, making it a good qubit for quantum applications, particularly sensing. 3) Quantum mechanical studies of the CISS effect will provide predictive models for molecular qubit design. 4) The CISS effect will be used to control, readout, and transfer information in prototypical devices embedding hybrid interfaces based on semiconducting or conducting substrates, thus dramatically advancing the use of molecular spins in quantum information technologies targeting high-temperature operation. These devices will be used also to prove molecule-based Quantum Error Correction. The knowledge acquired with CASTLE will impact a wide range of fields, including magnetless spintronics, dynamic nuclear polarization for NMR signal enhancement, catalysis, and light harvesting.