%0 Journal Article %D Submitted %T Realization of portable room temperature nanodiamond 13C hyperpolarizer %A A. Ajoy %A R. Nazaryan %A E. Druga %A K. Liu %A B. Han %A J.T. Oon %A M. Gierth %A R. Tsang %A J.H. Walton %A C.A. Meriles %A J.A. Reimer %A D. Suter %A A. Pines %G eng %0 Journal Article %J Proceedings of the National Academy of Science %D 2019 %T Dynamics of frequency-swept nuclear spin optical pumping in powdered diamond at low magnetic fields %A P.R. Zangara %A S. Dhomkar %A A. Ajoy %A K. Liu %A R. Nazaryan %A D. Pagliero %A D. Suter %A J. Reimer %A A. Pines %A C. Meriles %X

A broad effort is underway to improve the sensitivity of NMR through the use of dynamic nuclear polarization. Nitrogen vacancy (NV) centers in diamond offer an appealing platform because these paramagnetic defects can be optically polarized efficiently at room temperature. However, work thus far has been mainly limited to single crystals, because most polarization transfer protocols are sensitive to misalignment between the NV and magnetic field axes. Here we study the spin dynamics of NV−13C pairs in the simultaneous presence of optical excitation and microwave frequency sweeps at low magnetic fields. We show that a subtle interplay between illumination intensity, frequency sweep rate, and hyperfine coupling strength leads to efficient, sweep-direction-dependent 13C spin polarization over a broad range of orientations of the magnetic field. In particular, our results strongly suggest that finely tuned, moderately coupled nuclear spins are key to the hyperpolarization process, which makes this mechanism distinct from other known dynamic polarization channels. These findings pave the route to applications where powders are intrinsically advantageous, including the hyperpolarization of target fluids in contact with the diamond surface or the use of hyperpolarized particles as contrast agents for in vivo imaging.

%B Proceedings of the National Academy of Science %8 01/2019 %G eng %U https://www.pnas.org/content/early/2019/01/23/1811994116 %R https://doi.org/10.1073/pnas.1811994116 %0 Journal Article %J Review of Scientific Instruments %D 2019 %T Wide dynamic range magnetic field cycler: Harnessing quantum control at low and high fields %A A. Ajoy %A X. Lv %A E. Druga %A K. Liu %A B. Safvati %A A. Morabe %A M. Fenton %A R. Nazaryan %A S. Patel %A T. Sjolander %A J. Reimer %A D Sakellariou %A C. Meriles %A A. Pines %X

We describe the construction of a fast field cycling device capable of sweeping a 4-order-of-magnitude range of magnetic fields, from ∼1 mT to 7 T, in under 700 ms, and which is further extendable to a 1 nT-7 T range. Central to this system is a high-speed sample shuttling mechanism between a superconducting magnet and a magnetic shield, with the capability to access arbitrary fields in between with high resolution. Our instrument serves as a versatile platform to harness the inherent dichotomy of spin dynamics on offer at low and high fields—in particular, the low anisotropy, fast spin manipulation, and rapid entanglement growth at low field as well as the long spin lifetimes, spin specific control, and efficient inductive measurement possible at high fields. Exploiting these complementary capabilities in a single device opens up applications in a host of problems in quantum control, sensing, and information storage, besides in nuclear hyperpolarization, relaxometry, and imaging. In particular, in this paper, we focus on the ability of the device to enable low-field hyperpolarization of 13C nuclei in diamond via optically pumped electronic spins associated with nitrogen vacancy defect centers.

%B Review of Scientific Instruments %V 90 %8 01/2019 %G eng %U https://aip.scitation.org/doi/10.1063/1.5064685 %R https://doi.org/10.1063/1.5064685