Jacob Olshansky

Assistant Professor of Chemistry at the University of Massachusetts Amherst

Host: Dr. Aaron Rossini

Physical and Theoretical Chemistry

"Quantum Dot–Organic Molecule Conjugates as Hosts for Photogenerated Spin Qubit Pairs"

The inherent spin polarization present in photogenerated spin-correlated radical pairs makes them promising candidates for quantum computing and quantum sensing applications. The spin states of these systems can be probed and manipulated with microwave pulses using electron paramagnetic resonance spectrometers. However, there are no prior reports on magnetic resonance-based spin measurements of photogenerated spin-correlated radical pairs hosted on quantum dots. In the current work, we prepare dye molecule–inorganic quantum dot conjugates and show that they can produce photogenerated spin-polarized states. A series of dye molecules are chosen for their ability to undergo efficient charge separation, and the nanoparticle materials, ZnO quantum dots, are chosen for their promising spin properties. Transient and steady state optical spectroscopy performed on ZnO quantum dot–organic dye conjugates shows that reversible photogenerated charge separation is occurring. Transient and pulsed electron paramagnetic resonance experiments are then performed on the photogenerated radical pairs, which demonstrate that (1) the radical pairs are polarized at moderate temperatures and well modeled by existing theories and (2) the spin states can be accessed and manipulated with microwave pulses. This work opens the door to a new class of promising qubit materials that can be photogenerated in polarized states and hosted by highly tailorable inorganic nanoparticles.