Publications

Conspectus Preparing and manipulating pure magnetic states in molecular systems are the key initial requirements for harnessing the power of synthetic chemistry to drive practical quantum sensing and computing technologies. One route for achieving the requisite higher spin states in organic systems exploits the phenomenon of singlet fission, which produces...

Surface charge-carrier traps are ubiquitous in colloidal semiconductor nanocrystals and fundamentally impact excited-state relaxation, making it critical to understand both their nature and their dynamics. Here, using photoluminescence upconversion and transient absorption spectroscopy, we study hole trapping and the dissociation between electrons and trapped holes in nonuniform CdSe nanorods and...

Charge-carrier traps play a central role in the excited-state dynamics of semiconductor nanocrystals, but their influence is often difficult to measure directly. In CdS and CdSe nanorods of nonuniform width, spatially separated electrons and trapped holes display relaxation dynamics that follow a power-law function in time that is consistent with...

The photo-driven process of singlet fission generates coupled triplet pairs (TT) with fundamentally intriguing and potentially useful properties. The quintet 5TT0 sublevel is particularly interesting for quantum information because it is highly entangled, addressable with microwave pulses, and could be detected using optical techniques. Previous theoretical work on a model...

Singlet fission, a process that splits a singlet exciton into a biexciton, has promise in quantum information. We report time-resolved electron paramagnetic resonance measurements on a molecule, TIPS-BP1′, designed to exhibit strongly state-selective relaxation to specific magnetic spin sublevels. The resulting optically pumped "spin polarization" is a nearly pure initial...

Short coherence times present a primary obstacle in quantum computing and sensing applications. In atomic systems, clock transitions (CTs), formed from avoided crossings in an applied Zeeman field, can substantially increase coherence times. We show how CTs can dampen intrinsic and extrinsic sources of quantum noise in molecules. Conical intersections...

Singlet fission is a photoconversion process that generates a doubly excited, maximally spin entangled pair state. This state has applications to quantum information and computing that are only beginning to be realized. In this article, we construct and analyze a spin-exciton hamiltonian to describe the dynamics of the two-triplet state...

We examine the role of electronic polarizability in water on short (tens of femtoseconds), intermediate (hundreds of femtoseconds), and long (≈1 ps) time scales by comparing molecular dynamics results to experimental data for vibrational spectroscopy of HOD in liquid D 2 O. Because the OH absorption frequency is sensitive to...

Recent experiments in living cells have observed subdiffusive motion, where the mean squared displacement of a molecule grows sublinearly with time as 〈 x 2 〉∼ t α . Motivated by these experiments, we develop a theory for subdiffusion-limited bimolecular enzyme kinetics. As in normal diffusion, the statistics of the...

We present a theory for carrier transport in semiconducting nanoscale heterostructures that emphasizes the effects of strain at the interface between two different crystal structures. An exactly solvable model shows that the interface region, or junction, acts as a scattering potential that facilitates charge separation. As a case study, we...