The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Alexander Pines - One of the best experts on this subject based on the ideXlab platform.
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magnetic field induced delocalization in hybrid electron Nuclear Spin ensembles
arXiv: Mesoscale and Nanoscale Physics, 2020Co-Authors: Daniela Pagliero, Ashok Ajoy, Alexander Pines, Pablo R Zangara, Jacob Henshaw, Rodolfo H Acosta, Neil B Manson, Jeffrey A Reimer, Carlos A. MerilesAbstract:We use field-cycling-assisted dynamic Nuclear polarization to demonstrate magnetic-field-dependent activation of Nuclear Spin transport from otherwise isolated strongly-hyperfine-coupled sites. With the help of a toy model comprising electron and Nuclear Spins, we recast our observations in terms of a dynamic phase diagram featuring zones of active or forbidden Nuclear Spin current separated by boundaries defined by the interplay between Spin Zeeman, dipolar, and hyperfine couplings. Analysis of the polarization transport as a function of the driving field reveals the presence of many-body excitations stemming from the hybrid electron-Nuclear nature of the system. These findings could prove relevant in applications to Spin-based quantum information processing and nanoscale sensing.
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Room-temperature in situ Nuclear Spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond
Nature Communications, 2015Co-Authors: Jonathan P. King, Keunhong Jeong, Chang S Shin, Claudia E Avalos, Hai-jing Wang, Ralph H. Page, Christophoros C. Vassiliou, Alexander PinesAbstract:Low detection sensitivity stemming from the weak polarization of Nuclear Spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance Nuclear Spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C Nuclear Spins observed via high-field magnetic resonance. The technique harnesses the high optically induced Spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic Nuclear polarization. We observe bulk Nuclear Spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal of the hyperpolarized Spins was detected in situ with a standard Nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. Hyperpolarization via optical pumping/dynamic Nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for Nuclear magnetic resonance of solids and liquids under ambient conditions.
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liquid state Nuclear Spin comagnetometers
Bulletin of the American Physical Society, 2012Co-Authors: M P Ledbetter, Alexander Pines, Szymon Pustelny, Dmitry Budker, Michael Romalis, John W BlanchardAbstract:We discuss Nuclear Spin comagnetometers based on ultralow-field Nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different Nuclear Spin. In one version thereof, Larmor precession of protons and $^{19}\mathrm{F}$ nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\text{ }\text{ }\mathrm{Hz}$, or about $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }\mathrm{Hz}$ in $\ensuremath{\approx}1$ day of integration. In a second version, Spin precession of protons and $^{129}\mathrm{Xe}$ nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to Spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.
Paola Cappellaro - One of the best experts on this subject based on the ideXlab platform.
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Atomic-scale Nuclear Spin imaging using quantum-assisted sensors in diamond
Physical Review X, 2015Co-Authors: Ashok Ajoy, U. Bissbort, Mikhail Lukin, Mikhail D. Lukin, Ronald L. Walsworth, Paola CappellaroAbstract:Nuclear Spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nano-scale sensors has given hope of achieving the long-standing goal of single-protein, high spatial-resolution structure determination in their natural environment and ambient conditions. In particular, quantum sensors based on the Spin-dependent photoluminescence of Nitrogen Vacancy (NV) centers in diamond have recently been used to detect nanoscale ensembles of external Nuclear Spins. While NV sensitivity is approaching single-Spin levels, extracting relevant information from a very complex structure is a further challenge, since it requires not only the ability to sense the magnetic field of an isolated Nuclear Spin, but also to achieve atomic-scale spatial resolution. Here we propose a method that, by exploiting the coupling of the NV center to an intrinsic quantum memory associated with the Nitrogen Nuclear Spin, can reach a tenfold improvement in spatial resolution, down to atomic scales. The spatial resolution enhancement is achieved through coherent control of the sensor Spin, which creates a dynamic frequency filter selecting only a few Nuclear Spins at a time. We propose and analyze a protocol that would allow not only sensing individual Spins in a complex biomolecule, but also unraveling couplings among them, thus elucidating local characteristics of the molecule structure.
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Stable three-axis Nuclear-Spin gyroscope in diamond
Physical Review A - Atomic Molecular and Optical Physics, 2012Co-Authors: Ashok Ajoy, Paola CappellaroAbstract:We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 Nuclear Spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic Spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.
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Imaging mesoscopic Nuclear Spin noise with a diamond magnetometer
Journal of Chemical Physics, 2010Co-Authors: Carlos A. Meriles, Jonathan S. Hodges, Garry Goldstein, Mikhail D. Lukin, Liang Jiang, Paola CappellaroAbstract:Magnetic Resonance Imaging (MRI) can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale Nuclear Spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring Nuclear Spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long Nuclear Spin correlation times to reconstruct a local, high-resolution sample spectrum.
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coherence of an optically illuminated single Nuclear Spin qubit
Physical Review Letters, 2008Co-Authors: Liang Jiang, E. Togan, Paola Cappellaro, M Gurudev V Dutt, Lily Childress, Jacob M Taylor, Mikhail D. LukinAbstract:We investigate the coherence properties of individual Nuclear Spin quantum bits in diamond [Dutt et al., Science 316, 1312 (2007)] when a proximal electronic Spin associated with a nitrogen-vacancy (N-V) center is being interrogated by optical radiation. The resulting Nuclear Spin dynamics are governed by time-dependent hyperfine interaction associated with rapid electronic transitions, which can be described by a Spin-fluctuator model. We show that due to a process analogous to motional averaging in Nuclear magnetic resonance, the Nuclear Spin coherence can be preserved after a large number of optical excitation cycles. Our theoretical analysis is in good agreement with experimental results. It indicates a novel approach that could potentially isolate the Nuclear Spin system completely from the electronic environment. Nuclear Spins are of fundamental importance for storage and processing of quantum information. Their excellent coherence properties make them a superior qubit candidate even in room temperature solids. Unfortunately, their weak coupling to the environment also makes it difficult to isolate and manipulate individual nuclei. Recently, coherent preparation, manipulation and readout of individual 13 C Nuclear Spins in the diamond lattice were demonstrated [1,2]. These experiments make use of optical polarization and manipulation of the electronic Spin associated with a nitrogen-vacancy (N-V) color center in the diamond lattice [3‐6]. This enables reliable control of the Nuclear Spin qubit via hyperfine interactions with the electronic Spin. In order to be useful for applications in scalable quantum information processing [3], such as quantum communication [7] and quantum computation [8], the quantum coherence of the Nuclear Spins must be maintained even when the electronic state is undergoing fast transitions associated with optical measurement and with entanglement generation between electronic Spins. In this Letter, we investigate coherence properties of such an optically illuminated Nuclear Spin-electron Spin system. We show that these properties are well-described by a Spin-fluctuator model [9‐ 12], involving a single Nuclear Spin (system) coupled by the hyperfine interaction to an electron [13] (fluctuator) that undergoes rapid optical transitions and mediates the coupling between the Nuclear Spin and the environment. We generalize the Spin-fluctuator model to a vector description, necessary for single N-V centers in diamond [1], and make direct comparisons with experiments. Most importantly we demonstrate that the decoherence of the Nuclear Spin due to the rapidly fluctuating electron is greatly suppressed via a mechanism analogous to motional narrowing in Nuclear magnetic resonance (NMR) [14,15], allowing the Nuclear Spin coherence to be preserved even after hundreds of optical excitation cycles. We further show that by proper tuning of experimental parameters it may be possible to completely decouple the Nuclear Spin system from the electronic environment. The Spinfluctuator model discussed here for N-V centers can be generalized to other AMO systems (see Refs. [16,17] for the recent progress). The essential idea of this work is illustrated in Fig. 1. We consider an individual Nuclear Spin system (I " 1=2, associated with a 13 C atom) that is weakly coupled to the electronic Spin of an N-V center via the hyperfine interaction. The transitions between ground and optically excited electronic states are caused by laser light and spontaneous emission of photons. The strength of the hyperfine interFIG. 1 (color online). (a) Energy levels (left) and schematic model (right) for optical transitions between different electronic states (jai and jbi), with transition rates rba and rab. The precession of the Nuclear Spin ( ~ !a or ~
Norikazu Mizuochi - One of the best experts on this subject based on the ideXlab platform.
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coherence of single Spins coupled to a Nuclear Spin bath of varying density
Physical Review B, 2009Co-Authors: Petr Siyushev, Florian Rempp, Philipp Neumann, Norikazu Mizuochi, J Beck, V Jacques, Kazuo Nakamura, D J Twitchen, Hideyuki WatanabeAbstract:The dynamics of single electron and Nuclear Spins in a diamond lattice with different 13 C Nuclear Spin concentration is investigated. It is shown that coherent control of up to three individual nuclei in a dense Nuclear Spin cluster is feasible. The free-induction decays of Nuclear Spin Bell states and single Nuclear coherences among 13 C Nuclear Spins are compared and analyzed. Reduction in a free-induction-decay time T2 and a coherence time T2 upon increase in Nuclear Spin concentration has been found. For pure diamond, T 2 as long as 30 s and T2 of up to 0.65 ms for the electron Spin has been observed. The 13 C concentration dependence of T 2 is explained by Fermi contact and dipolar interactions with nuclei in the lattice. It has been found that T2 decreases approximately as 1 / n, where n is 13 C concentration, which corresponds to the reported theoretical line of T2 for an electron Spin interacting with a Nuclear Spin bath.
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coherence of single Spins coupled to a Nuclear Spin bath of varying density
Physical Review B, 2009Co-Authors: Petr Siyushev, Florian Rempp, Philipp Neumann, Norikazu Mizuochi, J Beck, V Jacques, Kazuo Nakamura, D J Twitchen, Hideyuki WatanabeAbstract:The dynamics of single electron and Nuclear Spins in a diamond lattice with different $^{13}\text{C}$ Nuclear Spin concentration is investigated. It is shown that coherent control of up to three individual nuclei in a dense Nuclear Spin cluster is feasible. The free-induction decays of Nuclear Spin Bell states and single Nuclear coherences among $^{13}\text{C}$ Nuclear Spins are compared and analyzed. Reduction in a free-induction-decay time ${T}_{2}^{\ensuremath{\ast}}$ and a coherence time ${T}_{2}$ upon increase in Nuclear Spin concentration has been found. For pure diamond, ${T}_{2}^{\ensuremath{\ast}}$ as long as $30\text{ }\ensuremath{\mu}\text{s}$ and ${T}_{2}$ of up to 0.65 ms for the electron Spin has been observed. The $^{13}\text{C}$ concentration dependence of ${T}_{2}^{\ensuremath{\ast}}$ is explained by Fermi contact and dipolar interactions with nuclei in the lattice. It has been found that ${T}_{2}$ decreases approximately as $1/n$, where $n$ is $^{13}\text{C}$ concentration, which corresponds to the reported theoretical line of ${T}_{2}$ for an electron Spin interacting with a Nuclear Spin bath.
Koichi Oyanagi - One of the best experts on this subject based on the ideXlab platform.
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observation of Nuclear Spin seebeck effect
arXiv: Materials Science, 2021Co-Authors: Takashi Kikkawa, D Reitz, Hayate Ito, Takahiko Makiuchi, T Sugimoto, K Tsunekawa, Shunsuke Daimon, Koichi Oyanagi, R RamosAbstract:Thermoelectric effects have been applied to power generators and temperature sensors that convert waste heat into electricity. The effects, however, have been limited to electrons to occur, and inevitably disappear at low temperatures due to electronic entropy quenching. Here, we report thermoelectric generation caused by Nuclear Spins in a solid: Nuclear-Spin Seebeck effect. The sample is a magnetically ordered material MnCO$_{3}$ having a large Nuclear Spin ($I = 5/2$) of $^{55}$Mn nuclei and strong hyperfine coupling, with a Pt contact. In the system, we observe low-temperature thermoelectric signals down to 100 mK due to Nuclear-Spin excitation. Our theoretical calculation in which interfacial Korringa process is taken into consideration quantitatively reproduces the results. The Nuclear thermoelectric effect demonstrated here offers a way for exploring thermoelectric science and technologies at ultralow temperatures.
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observation of Nuclear Spin seebeck effect
Nature Communications, 2021Co-Authors: Takashi Kikkawa, D Reitz, Hayate Ito, Takahiko Makiuchi, T Sugimoto, K Tsunekawa, Shunsuke Daimon, Koichi OyanagiAbstract:Thermoelectric effects have been applied to power generators and temperature sensors that convert waste heat into electricity. The effects, however, have been limited to electrons to occur, and inevitably disappear at low temperatures due to electronic entropy quenching. Here, we report thermoelectric generation caused by Nuclear Spins in a solid: Nuclear-Spin Seebeck effect. The sample is a magnetically ordered material MnCO3 having a large Nuclear Spin (I = 5/2) of 55Mn nuclei and strong hyperfine coupling, with a Pt contact. In the system, we observe low-temperature thermoelectric signals down to 100 mK due to Nuclear-Spin excitation. Our theoretical calculation in which interfacial Korringa process is taken into consideration quantitatively reproduces the results. The Nuclear thermoelectric effect demonstrated here offers a way for exploring thermoelectric science and technologies at ultralow temperatures. Thermoelectric effects are limited to electrons to occur, and disappear at low temperatures due to electronic entropy quenching. Here, the authors report thermoelectric generation caused by Nuclear Spins down to 100 mK due to Nuclear-Spin excitation in a magnetically ordered material MnCO3.
Wolfgang Wernsdorfer - One of the best experts on this subject based on the ideXlab platform.
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Nuclear Spin isomers engineering a et4 n dypc2 Spin qudit
Angewandte Chemie, 2017Co-Authors: Eufemio Morenopineda, Mario Ruben, Wolfgang Wernsdorfer, Marko Damjanovic, Olaf FuhrAbstract:Two dysprosium isotopic isomers were synthesized: Et4 N[163 DyPc2 ] (1) with I=5/2 and Et4 N[164 DyPc2 ] (2) with I=0 (where Pc=phthalocyaninato). Both isotopologues are single-molecule magnets (SMMs); however, their relaxation times as well as their magnetic hystereses differ considerably. Quantum tunneling of the magnetization (QTM) at the energy level crossings is found for both systems via ac-susceptibility and μ-SQUID measurements. μ-SQUID studies of 1(I=5/2) reveal several Nuclear-Spin-driven QTM events; hence determination of the hyperfine coupling and the Nuclear quadrupole splitting is possible. Compound 2(I=0) shows only strongly reduced QTM at zero magnetic field. 1(I=5/2) could be used as a multilevel Nuclear Spin qubit, namely qudit (d=6), for quantum information processing (QIP) schemes and provides an example of novel coordination-chemistry-discriminating Nuclear Spin isotopes. Our results show that the Nuclear Spin of the lanthanide must be included in the design principles of molecular qubits and SMMs.
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Electrically driven Nuclear Spin resonance in single-molecule magnets
Science, 2014Co-Authors: Stefan Thiele, Franck Balestro, Rafik Ballou, Svetlana Klyatskaya, Mario Ruben, Wolfgang WernsdorferAbstract:Recent advances in addressing isolated Nuclear Spins have opened up a path toward using Nuclear-Spin-based quantum bits. Local magnetic fields are normally used to coherently manipulate the state of the Nuclear Spin; however, electrical manipulation would allow for fast switching and spatially confined Spin control. Here, we propose and demonstrate coherent single Nuclear Spin manipulation using electric fields only. Because there is no direct coupling between the Spin and the electric field, we make use of the hyperfine Stark effect as a magnetic field transducer at the atomic level. This quantum-mechanical process is present in all Nuclear Spin systems, such as phosphorus or bismuth atoms in silicon, and offers a general route toward the electrical control of Nuclear-Spin-based devices.
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Electrical Readout of Individual Nuclear Spin Trajectories in a Single-Molecule Magnet Spin Transistor
Physical Review Letters, 2013Co-Authors: Stefan Thiele, Franck Balestro, Svetlana Klyatskaya, Mario Ruben, Romain Vincent, Holzmann Markus, Wolfgang WernsdorferAbstract:We present the electrical readout of time trajectories obtained from an isolated Nuclear Spin. The device, a TbPc2 single-molecule magnet Spin transistor, detects the four different Nuclear Spin states of the Tb3+ ion with fidelities better than 69%, allowing us to measure individual relaxation times (T1) of several tens of seconds. A good agreement with quantum Monte Carlo simulations suggests that the relaxation times are limited by the current tunneling through the transistor, which opens up the possibility to tune T1 electrically by means of bias and gate voltages.
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landau zener tunneling of a single tb 3 magnetic moment allowing the electronic read out of a Nuclear Spin
Physical Review B, 2013Co-Authors: Matias Urdampilleta, Svetlana Klyatskaya, Mario Ruben, Wolfgang WernsdorferAbstract:A multi-terminal device based on a carbon nanotube quantum dot was used at very low tem- perature to probe a single electronic and Nuclear Spin embedded in a bis-phthalocyanine Terbium (III) complex (TbPc2). A Spin-valve signature with large conductance jumps was found when two molecules were strongly coupled to the nanotube. The application of a transverse field separated the magnetic signal of both molecules and enabled single-shot read-out of the Terbium Nuclear Spin. The Landau-Zener (LZ) quantum tunneling probability was studied as a function of field sweep rate, establishing a good agreement with the LZ equation and yielding the tunnel splitting \Delta. It was found that ? increased linearly as a function of the transverse field. These studies are an essential prerequisite for the coherent manipulation of a single Nuclear Spin in TbPc2.
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electronic read out of a single Nuclear Spin using a molecular Spin transistor
Nature, 2012Co-Authors: Romain Vincent, Mario Ruben, Svetlana Klyatskaya, Wolfgang Wernsdorfer, Franck BalestroAbstract:The long-lived Nuclear Spin state of an individual metal atom embedded in a single-molecule magnet is shown to be readable electronically. Nuclear Spins are increasingly being considered for the role of active elements in a quantum computer: in contrast to electronic Spins they are well isolated from the environment, a favourable condition for achieving stable quantum coherence. The challenge is to address and manipulate these Spins. Romain Vincent et al. bring such applications closer by showing that the long-lived Nuclear-Spin state of an individual metal atom embedded in a single-molecule magnet can be read electronically. They observe long Nuclear-Spin lifetimes — tens of seconds — and are able to determine the dynamics of Spin states. Quantum control of individual Spins in condensed-matter devices is an emerging field with a wide range of applications, from nanoSpintronics1,2 to quantum computing3. The electron, possessing Spin and orbital degrees of freedom, is conventionally used as the carrier of quantum information in proposed devices4,5,6,7,8,9. However, electrons couple strongly to the environment, and so have very short relaxation and coherence times. It is therefore extremely difficult to achieve quantum coherence and stable entanglement of electron Spins. Alternative concepts propose Nuclear Spins as the building blocks for quantum computing10, because such Spins are extremely well isolated from the environment and less prone to decoherence. However, weak coupling comes at a price: it remains challenging to address and manipulate individual Nuclear Spins11,12,13,14. Here we show that the Nuclear Spin of an individual metal atom embedded in a single-molecule magnet can be read out electronically. The observed long lifetimes (tens of seconds) and relaxation characteristics of Nuclear Spin at the single-atom scale open the way to a completely new world of devices in which quantum logic may be implemented.
