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Abstract: Lattices of dipolar coupled nuclear spins in natural crystals are large, interacting quantum systems -- ideal platforms to study non-equilibrium many-body dynamics. Using the magnetic resonance toolkit, which includes Dynamic Nuclear Polarization (DNP), Hamiltonian engineering, and multiple-quantum Nuclear Magnetic Resonance (NMR) experiments, we studied aspects of coherent control, manipulation, and readout of the complex dynamics of the spin system.

First, DNP is shown to be a potential initial state preparation method that cools the nuclear spins to access the lower energy levels of the system. This is achieved by polarization transfer from electronic spins under resonant microwave excitation. We demonstrate high nuclear polarization and NMR signal enhancement of 13C spins in diamond using microwave irradiation of the substitutional nitrogen (P1) centers.

Furthermore, applying Hamiltonian engineering sequences, we control the system evolution. Specifically, we use a combination of numerical simulations and NMR experiments on adamantane to evaluate and compare the performance of several known sequences that aim to suppress the magnetic dipolar interaction between spins. The effect of sequence parameters and control errors on sequence performance is explored and the presence of local disorder is established, perhaps unsurprisingly, as a distinguishing factor in the decoupling efficiency of spectroscopic and time-suspension sequences. Additionally, we use time-reversal multiple-quantum experiments to probe the growth of multi-spin correlations involving large clusters of spins and explore the ability of time-suspension sequences to protect these correlated initial states.

Finally, we study a Hamiltonian with tunable interactions and disorder that can be engineered from the natural Hamiltonian of a heteronuclear spin system. Disorder plays a central role in determining the thermalization properties and dynamics of quantum Hamiltonians. We use numerical simulations of small 1D systems to demonstrate the possibility of an ergodic to non-ergodic transition of the Hamiltonian dynamics at high values of disorder. This transition is reflected in the change in behavior of multiple metrics of quantum ergodicity and information scrambling including eigenstate entanglement, statistics of the eigen spectrum, entanglement dynamics, and growth of an out-of-time-ordered commutator.

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https://dartmouth.zoom.us/j/91353004102?pwd=MOwN2TyH3pLZ4imIMKF41kFBb3p6N8.1

Meeting ID: 913 5300 4102
Email Physics.Department@dartmouth.edu for passcode.