Browsing by Author "Maze, J. R."

Now showing 1 - 8 of 8
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    Characterization of antiferromagnetic magnons using nitrogen vacancy center relaxometry
    (2024) Heitzer, R. C.; Pinto, F.; Rodriguez, E.; Rodriguez-Suarez, R.; Maze, J. R.
    Quantum impurities, such as nitrogen vacancy (NV) centers in diamond, exhibit excellent quantum coherence, single-spin sensitivity, and a significant capability to be optically manipulated. These defects act as single spin sensors, allowing the detection of local magnetic fields on length scales of tens of nanometers. Their relaxation rates, affected by the magnetic noise in their vicinity, could capture information about the dynamics of a magnetic environment. In recent years, NV centers have been increasingly utilized to measure magnetic properties of ferromagnetic materials and, on a few occasions, to study antiferromagnets with uniaxial anisotropy. Both systems have the capability to propagate spin waves, whose quanta are called magnons. However, a complete theoretical description of how NV centers interact with antiferromagnetic magnons is still a topic to explore. In this work, we calculate the NV center relaxation rates considering collinear anisotropic antiferromagnetic insulators, such as MnF2 2 and NiO, represented as magnon systems. For an easy-axis of anisotropy z " and an external magnetic field H 0 , we did these calculations for both H 0 H z " (antiferromagnetic phase) and H 0 1 z " (canted phase), finding that the relaxation rates are greater in the canted phase. Moreover, we found that NiO induces remarkably lower relaxation rates than MnF2, 2 , because of its high effective exchange field mu 0 H E 1000 T.
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    Effect of intersystem crossing rates and optical illumination on the polarization of nuclear spins close to nitrogen-vacancy centers
    (2021) Duarte, H.; Dinani, H. T.; Jacques, V; Maze, J. R.
    Several efforts have been made to polarize the nearby nuclear environment of nitrogen-vacancy (NV) centers for quantum metrology and quantum information applications. Different methods showed different nuclear spin polarization efficiencies and rely on electronic spin polarization associated to the NV center, which in turn crucially depends on the intersystem crossing. Recently, the rates involved in the intersystem crossing have been measured leading to different transition rate models. Here, we consider the effect of these rates on several nuclear polarization methods based on the level anticrossing, and precession of the nuclear population while the electronic spin is in the m(s) = 0 and m(s) = 1 spin states. We show that the nuclear polarization depends on the power of optical excitation used to polarize the electronic spin. The degree of nuclear spin polarization is different for each transition rate model. Therefore, the results presented here are relevant for validating these models and for polarizing nuclear spins. Furthermore, we analyze the performance of each method by considering the nuclear position relative to the symmetry axis of the NV center.
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    Optically Enhanced Electric Field Sensing Using Nitrogen-Vacancy Ensembles
    (2021) Block, M.; Kobrin, B.; Jarmola, A.; Hsieh, S.; Zu, C.; Figueroa, N. L.; Acosta, V. M.; Minguzzi, J.; Maze, J. R.; Budker, D.; Yao, N. Y.
    Nitrogen-vacancy (N-V) centers in diamond have shown promise as inherently localized electric field sensors, capable of detecting individual charges with nanometer resolution. Working with N-V ensembles, we demonstrate that a detailed understanding of the internal electric field environment enables enhanced sensitivity in the detection of external electric fields. We follow this logic along two complementary paths. First, using excitation tuned near the N-V's zero-phonon line, we perform optically detected magnetic resonance (ODMR) spectroscopy at cryogenic temperatures in order to precisely measure the N-V center's excited-state susceptibility to electric fields. In doing so, we demonstrate that the characteristically observed contrast inversion arises from an interplay between spin-selective optical pumping and the N-V centers' local charge distribution. Second, motivated by this understanding, we propose and analyze a method for optically enhanced electric field sensing using N-V ensembles; we estimate that our approach should enable order-of-magnitude improvements in the dc electric field sensitivity.
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    Physically motivated analytical expression for the temperature dependence of the zero-field splitting of the nitrogen-vacancy center in diamond
    (2023) Cambria, M. C.; Thiering, G.; Norambuena, A.; Dinani, H. T.; Gardill, A.; Kemeny, I.; Lordi, V.; Gali, A.; Maze, J. R.; Kolkowitz, S.
    The temperature dependence of the zero-field splitting (ZFS) between the vertical bar m(s) = 0 > and vertical bar m(s) = +/- 1 > levels of the nitrogen-vacancy (NV) center's electronic ground-state spin triplet can be used as a robust nanoscale thermometer in a broad range of environments. However, despite numerous measurements of this dependence in different temperature ranges, to our knowledge no analytical expression has been put forward that captures the scaling of the ZFS of the NV center across all relevant temperatures. Here we present a simple, analytical, and physically motivated expression for the temperature dependence of the NV center's ZFS that matches all experimental observations, in which the ZFS shifts in proportion to the occupation numbers of two representative phonon modes. In contrast to prior models our expression does not diverge outside the regions of fitting. We show that our model quantitatively matches experimental measurements of the ZFS from 15 to 500 K in single NV centers in ultrapure bulk diamond, and we compare our model and measurements to prior models and experimental data.
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    Room-temperature polarization of individual nuclear spins in diamond via anisotropic hyperfine coupling and coherent population trapping
    (2022) Jamonneau, P.; Dreau, A.; Hetet, G.; Roch, J. F.; Maze, J. R.; Jacques, V.
    We employ the electronic spin of a single nitrogen-vacancy (NV) defect in diamond to detect and control the quantum state of remote nuclear spins coupled by hyperfine interaction. More precisely, our work focuses on individual C-13 nuclei featuring a moderate hyperfine coupling strength (similar to 1 MHz) with the NV's electron spin. Two different methods providing an efficient room-temperature polarization of these peculiar C-13 nuclear spins are described. The first one is based on a polarization transfer from the NV electron spin to the C-13 nucleus, which is mediated by the anisotropic component of the hyperfine interaction. The second one relies on coherent population trapping (CPT) within a A-type energy-level configuration in the microwave domain, which enables to initialize the C-13 nuclear spin in any quantum state superposition on the Bloch sphere. This CPT protocol is performed in an unusual regime for which relaxation from the excited level of the Lambda-scheme is externally triggered by optical pumping and separated in time from coherent microwave excitations. For these two polarization techniques, we investigate the impact of optical illumination on the nuclear spin polarization efficiency. This work adds new methods to the quantum toolbox used for coherent control of individual nuclear spins in diamond, which might find applications in quantum metrology.
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    State-dependent phonon-limited spin relaxation of nitrogen-vacancy centers
    (2021) Cambria, M. C.; Gardill, A.; Li, Y.; Norambuena, A.; Maze, J. R.; Kolkowitz, S.
    Understanding the limits to the spin coherence of the nitrogen-vacancy (NV) center in diamond is vital to realizing the full potential of this quantum system. We show that relaxation on the vertical bar m(s) = -1 > <-> vertical bar m(s) = +1 > transition occurs approximately twice as fast as relaxation on the vertical bar m(s) = 0 <-> vertical bar m(s) = +/- 1 > transitions under ambient conditions in native NVs in high-purity bulk diamond. The rates we observe are independent of NV concentration over four orders of magnitude, indicating they are limited by spin-phonon interactions. We find that the maximum theoretically achievable coherence time for an NV at 295 K is limited to 6.8(2) ms. Finally, we present a theoretical analysis of our results that suggests Orbach-like relaxation from quasilocalized phonons or contributions due to higher-order terms in the spin-phonon Hamiltonian are the dominant mechanism behind vertical bar m(s) = -1 > <-> vertical bar m(s) = +1 > relaxation, motivating future measurements of the temperature dependence of this relaxation rate.
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    Structural characterization of the saxitoxin-targeting APTSTX1 aptamer using optical tweezers and molecular dynamics simulations
    (2019) Casanova-Morales, Nathalie; Figueroa, Nataniel L.; Alfaro, Karol; Montenegro, Felipe; Barrera, Nelson P.; Maze, J. R.; Wilson, Christian A. M.; Conejeros, Pablo
    Optical tweezers have enabled the exploration of picoNewton forces and dynamics in single-molecule systems such as DNA and molecular motors. In this work, we used optical tweezers to study the folding/unfolding dynamics of the APTSTX1-aptamer, a single-stranded DNA molecule with high affinity for saxitoxin (STX), a lethal neurotoxin. By measuring the transition force during (un)folding processes, we were able to characterize and distinguish the conformational changes of this aptamer in the presence of magnesium ions and toxin. This work was supported by molecular dynamics (MD) simulations to propose an unfolding mechanism of the aptamer-Mg+2 complex. Our results are a step towards the development of new aptamer-based STX sensors that are potentially cheaper and more sensitive than current alternatives.
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    Temperature-Dependent Spin-Lattice Relaxation of the Nitrogen-Vacancy Spin Triplet in Diamond
    (2023) Cambria, M. C.; Norambuena, A.; Dinani, H. T.; Thiering, G.; Gardill, A.; Kemeny, I.; Li, Y.; Lordi, V.; Gali, A.; Maze, J. R.; Kolkowitz, S.
    Spin-lattice relaxation within the nitrogen-vacancy (NV) center's electronic ground-state spin triplet limits its coherence times, and thereby impacts its performance in quantum applications. We report measurements of the relaxation rates on the NV center's jms 1/4 0i & DIVIDE;-> jms 1/4 ⠂1i and jms 1/4 -1i & DIVIDE;-> jms 1/4 thorn 1i transitions as a function of temperature from 9 to 474 K in high-purity samples. We show that the temperature dependencies of the rates are reproduced by an ab initio theory of Raman scattering due to second-order spin-phonon interactions, and we discuss the applicability of the theory to other spin systems. Using a novel analytical model based on these results, we suggest that the high-temperature behavior of NV spin-lattice relaxation is dominated by interactions with two groups of quasilocalized phonons centered at 68.2(17) and 167(12) meV.