Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session F31: Focus Session: Spin-Dependent Phenomena in Semiconductors: Defects in Diamond and SiC |
Hide Abstracts |
Sponsoring Units: GMAG DMP FIAP Chair: Michael Flatte, University of Iowa Room: 207A |
Tuesday, March 3, 2015 8:00AM - 8:12AM |
F31.00001: Nuclear magnetic resonance of external protons using continuous dynamical decoupling with shallow NV centers Charles De Las Casas, Kenichi Ohno, David D. Awschalom The nitrogen vacancy (NV) center in diamond is a paramagnetic defect with excellent spin properties that can reside within a few nanometers of the diamond surface, enabling atomic-scale magnetic resonance sensing of external nuclear spins. Here we use rotating frame longitudinal spin relaxation (T$_{\mathrm{1\rho }})$ based sensing schemes, known as Continuous Dynamical Decoupling (CDD), to detect external nuclear spins with shallow NV centers (\textless 5 nm from the surface). Distinguishing neighboring nuclear spins from each other requires the NV center be near enough to create differences in the hyperfine shifts and coupling strengths of the nuclei. However, spin coherence time and consequently the sensitivity of dynamical decoupling techniques degrade sharply as NVs become shallower. We use strong continuous driving to overcome this fast decoherence and detect an ensemble of external nuclear spins using a single shallow NV center with a short T$_{\mathrm{2}}$ (\textless 2$\mu $s) at magnetic fields as high as 0.5 Tesla. The increased sensitivity of this method relative to pulsed dynamical decoupling techniques demonstrates the benefits of CDD for sensing with very shallow NV centers. [Preview Abstract] |
Tuesday, March 3, 2015 8:12AM - 8:24AM |
F31.00002: High-field optically detected magnetic resonance of a single nitrogen-vacancy center in diamond Viktor Stepanov, Chathuranga Abeywardana, Franklin Cho, Rana Akiel, Susumu Takahashi A nitrogen-vacancy center (NV) in diamond is a promising candidate for fundamental investigation of spin physics and applications to quantum information processing and quantum sensing because of its remarkable properties such as long lived coherence, superb photostability and capability to detect a single NV center using an optically detected magnetic resonance (ODMR) technique. Here, we discuss a platform to investigate a NV center at high magnetic fields. We will present the development of a high-field ODMR system consisting of a high-frequency excitation component, superconducting magnet, NV detection system, microscope system and sample stage. We also discuss ODMR and double electron-electron resonance measurements of a single NV center at high magnetic fields. [Preview Abstract] |
Tuesday, March 3, 2015 8:24AM - 8:36AM |
F31.00003: Fast Room-Temperature Phase Gate on a Single Nuclear Spin in Diamond S. Sangtawesin, T.O. Brundage, J.R. Petta Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance as a result of the small nuclear magnetic moment. We demonstrate a fast $\sim 500$\ ns nuclear spin phase gate on a $^{14}$N nuclear spin qubit intrinsic to a nitrogen-vacancy center in high purity diamond [1]. This phase gate is achieved by utilizing electron-nuclear hyperfine interaction. By driving off-resonant Rabi oscillations on the electronic spin, we can generate an arbitrary phase gate on the nuclear spin. We also demonstrate that repeated applications of $\pi$-phase gates can bang-bang decouple the nuclear spin from the environment, locking the spin state for up to 140\ $\mu$s. \\[4pt] [1] S. Sangtawesin, T. O. Brundage, and J. R. Petta, Phys. Rev. Lett. 113, 020506 (2014) [Preview Abstract] |
Tuesday, March 3, 2015 8:36AM - 9:12AM |
F31.00004: Quantum control of orbital and spin dynamics in diamond using ultrafast optical pulses Invited Speaker: F. Joseph Heremans Optically addressable spin defects in solid-state materials have shown great potential for applications ranging from metrology to quantum information processing. Many of these experiments require a detailed understanding of the full Hamiltonian dynamics in order to develop precise quantum control. Here we use picosecond resonant optical pulses to investigate the coherent orbital and spin dynamics of the nitrogen-vacancy (NV) center in diamond, over timescales spanning six orders of magnitude. We implement an ultrafast optical pump-probe technique to study the NV center's orbital-doublet, spin-triplet excited state at cryogenic temperatures (T \textless\ 20 K), where the excited state becomes stable and optically coherent with the ground state. This technique, coupled with optical polarization selection rules, allows us to probe the coherent orbital dynamics of the NV center's excited state [1]. These experiments reveal dynamics on femtosecond to nanosecond timescales due to the interplay between the ground and excited state orbital levels. This all-optical technique also provides a method to dynamically control the spin state of the NV center by harnessing the excited state structure. Through studying the spin dynamics of the NV center with coherent pulses of light, we are able to rotate the spin state on sub-nanosecond timescales. Furthermore, by tuning the excited-state spin Hamiltonian with an external magnetic field, we demonstrate arbitrary-axis spin rotations through controlled unitary evolution of the spin state. Extending this to the full excited-state manifold, we develop a time-domain quantum tomography technique to precisely map the NV center's excited state Hamiltonian. These techniques generalize to other systems and can be a powerful tool in characterizing and controlling qubits in other optically addressable spin systems. \\[4pt] [1] L. C. Bassett*, F. J. Heremans*, D. J. Christle, C. G. Yale, G. Burkard, B. B. Buckley, and D. D. Awschalom, Science 345, 1333 (2014). [Preview Abstract] |
Tuesday, March 3, 2015 9:12AM - 9:24AM |
F31.00005: Electron spin lifetimes in 1e14 cm$^{-3}$ proton irradiated SiC Kyle Miller, John Colton, Sam Carter Silicon vacancies created by irradiation with protons or electrons in 4H silicon carbide (SiC) are potential spintronic devices. In our experiments, electron spin states are polarized with 870 nm laser light, and we manipulate the spins with resonant microwaves at 10.47 GHz and a magnetic field of 350 mT. Spin states are detected by the change in photoluminescence from the silicon defects, and lifetimes are calculated through optically detected spin resonance and electron spin echo. We have measured T$_{2}$ lifetimes in 1e14 cm$^{-3}$ proton irradiated SiC to be about 16 $\mu$s at various temperatures, fairly independent with temperature. Future plans include studying how defect density will impact spin lifetimes. [Preview Abstract] |
Tuesday, March 3, 2015 9:24AM - 9:36AM |
F31.00006: Spin states of the silicon vacancy in silicon carbide Michel Bockstedte, Felix Schuetz SiC as a semi conductor fulfills all necessary requirements$^1$ for implementing qubits via defect electron spins, such as the silicon vacancy, the di-vacancy or a complex of a silicon vacancy and a nitrogen impurity. The spin-selective fluorescence in contrast to the prototypical NV-center in diamond operates in the spectral range favorable for telecom applications.Spin-manipulation of the intrinsic centers was demonstrated even at room temperature.$^{2,3}$ For the silicon vacancy in SiC inter system crossings (ISCs) from high to yet unknown low spin states govern the spin-relaxation. By DFT and a DFT-based multi-reference Hamiltonian we analyze the spin physics of the defect. In 4H SiC distinct luminescence lines are obtained for the inequivalent defect sites in agreement with experiment. Our result thus establishes an assignment of the lines to the sites. Owing to the spin (S=3/2) and a stronger electron-phonon coupling in the excited state, we find ISCs distinct from the NV-center.\\ $^1$ J.~R.~Weber \emph{et al.}, PNAS \textbf{107}, 8513 (2010).\\ $^2$ F.~Koehl \emph{et al.}, Nature\textbf{479}, 84 (2011).\\ $^3$ V.~A.~Soltamov \emph{et al.}, Phys.~Rev.~Lett.~\textbf{108} 226402 (2012).\\ $^4$ E.~Janz\'{e}n \emph{et al.} Physica B \textbf{404}, 4354 (2009). [Preview Abstract] |
Tuesday, March 3, 2015 9:36AM - 9:48AM |
F31.00007: Near unity optical spin polarization of $^{29}$Si nuclei in silicon carbide W.F. Koehl, A.L. Falk, P.V. Klimov, D.J. Christle, D.D. Awschalom, K. Sz\'{a}sz, V. Iv\'{a}dy, A. Gali We demonstrate optical polarization of $^{29}$Si nuclei that are coupled to the electronic spins bound at neutral divacancy and PL6 defects in 4$H$- and 6$H$-SiC. We polarize high concentrations (10$^{16}$ cm$^{-3})$ of nuclear spins and measure efficient nuclear polarization at temperatures ranging from 5 K up to room temperature. The peak polarization is near unity (99 $\pm$ 1\%), corresponding to a 5 $\mu$K effective nuclear bath temperature. To explain the large polarization, we locate the spin transitions of the defects' optically excited electronic states and show that nuclear orientation is strongest at the ground and excited state spin-sublevel anticrossings. These findings suggest that nuclear polarization in SiC is a powerful platform for quantum memories, nuclear gyroscopes, and probes for magnetic resonance imaging. [Preview Abstract] |
Tuesday, March 3, 2015 9:48AM - 10:00AM |
F31.00008: Ground-state magnetic properties of transition-metal dopants in silicon carbide Wenhao Hu, Michael E. Flatt\'{e} Recently, a decoherence-free subspace(DFS) system has been predicted in the substitutional nickel spin center of diamond [1]. Here we describe our investigations of substitutional transition metal dopants in 3C silicon carbide using density functional theory in the SGGA approximation. We used a 64-atom supercell for the silicon carbide host, inserted a dopant atom (Ni or Cr) at a single carbon or a single silicon site. The atomic positions were allowed to relax with a force precision of 0.1 mRy/a.u. The Heisenberg exchange coupling energy J was calculated as a function of hydrostatic strain. An antiferromagnetic-ferromagnetic transition can be seen in nickel spin centers at certain strains. A model of two spatially separated spins can be used to explain the dependence of J on the atomic separation. By applying a magnetic field, we predict two of the triplet states can be split off so as to create a DFS. Strain modulation and resonant microwave can be exploited to manipulate the qubit. Finally, the experimental feasibility of our scheme is evaluated. \\[4pt] [1] T. Chanier, C. E. Pryor, M. E. Flatt\'{e}, Europhys. Lett. 99, 67006 (2012) [Preview Abstract] |
Tuesday, March 3, 2015 10:00AM - 10:12AM |
F31.00009: spds* Tight-Binding Model for Exchange Interaction Between Transition Metal Dopants in Diamond and SiC Victoria R. Kortan, C\"{u}neyt \c{S}ahin, Michael E. Flatt\'e Diamond and SiC are wide-band-gap semiconductors with long-lived spin lifetimes[1,2] and promising for quantum information technology device design. Spin initialization, manipulation and readout has already been demonstrated for the NV center in diamond[3] and the divacancy in SiC[4]. Transition metal spin centers offer additional benefits in tetrahedral hosts due to the crystal field splitting of the d-states into localized and extended states. For example, the application of strain in diamond allows switching between two spin states of a single Ni dopant[5]. Here we use a spds* tight-binding model including spin-orbit interaction to describe transition metal spin centers in diamond and 3C-SiC as well as the NV center in diamond and divacancy in 3C-SiC. The energy levels for an isolated dopant are taken from experiment, when available, and density functional theory calculations otherwise. We calculate and compare the wavefunctions of these spin centers, as well as the strength of the exchange interaction between pairs of them.\\[4pt] [1] A. Falk, et al, Nature Comm. 4, 1819 (2013).\\[0pt] [2] G. Balasubramanian, et al, Nature Mat. 8, 383 (2009).\\[0pt] [3] N.B. Manson, et al, Phys. Rev. B 74, 104303 (2006).\\[0pt] [4] W.F. Koehl, et al, Nature 479, 84 (2011).\\[0pt] [5] T. Chanier, et al, EPL 99, 67006 (2012). [Preview Abstract] |
Tuesday, March 3, 2015 10:12AM - 10:24AM |
F31.00010: Isolation and Control of Spins in Silicon Carbide with Millisecond-Coherence Times David J. Christle, Abram L. Falk, Paolo Andrich, Paul V. Klimov, David D. Awschalom, Jawad Ul Hassan, Nguyen T. Son, Erik Janz\'{e}n, Takeshi Ohshima The elimination of defects from silicon carbide (SiC) has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. We demonstrate that individual electronic spin states of the divacancy defect in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled\footnote{D. J. Christle, A. L. Falk, P. Andrich, P. V. Klimov, J. Hassan, N. T. Son, E. Janz\'{e}n, T. Ohshima, and D. D. Awschalom, Nat. Mater. (to be published)}. This defect has analogous behavior to the prominent nitrogen-vacancy center in diamond, yet exists in a material amenable to modern growth and microfabrication techniques. We spectroscopically identify the different forms of divacancies, and show that divacancy spins exhibit an exceptionally long ensemble Hahn-echo coherence time that exceeds one millisecond. [Preview Abstract] |
Tuesday, March 3, 2015 10:24AM - 10:36AM |
F31.00011: Two-dimensional nanoscale imaging of gadolinium spins via scanning probe relaxometry with a single spin in diamond Matthew Pelliccione, Bryan Myers, Laetitia Pascal, Anand Das, Ania Jayich Spin-labeling of molecules with paramagnetic ions is an important approach for determining molecular structure, however current ensemble techniques lack the sensitivity to detect few isolated spins. In this talk, we demonstrate two-dimensional nanoscale imaging of paramagnetic gadolinium compounds using scanning relaxometry of a single nitrogen vacancy (NV) center in diamond. Gadopentetate dimeglumine attached to an atomic force microscope tip is controllably interacted with and detected by the NV center, by virtue of the fact that the NV exhibits fast relaxation in the fluctuating magnetic field generated by electron spin flips in the gadolinium. We demonstrate a reduction in the $T_1$ relaxation time of the NV center by over two orders of magnitude, probed with a spatial resolution of 20 nm, limited by thermal drift in ambient conditions. We discuss the importance of mitigating drift to reach truly nanoscale imaging and present progress towards cryogenic scanning magnetometry, along with utilizing chemically functionalized tips to gain greater control over the Gd distribution on the tip. Our result exhibits the viability of the technique for imaging individual spins attached to complex nanostructures or biomolecules, along with studying the magnetic dynamics of isolated spins. [Preview Abstract] |
Tuesday, March 3, 2015 10:36AM - 10:48AM |
F31.00012: Coherent Control of a Nitrogen-Vacancy Center Spin Ensemble with a Diamond Mechanical Resonator F. Guo, E.R. MacQuarrie, T.A. Gosavi, A.M. Moehle, N.R. Jungwirth, S.A. Bhave, G.D. Fuchs In contrast to the traditional coherent control of the nitrogen vacancy (NV) center in diamond's triplet spin state with ac magnetic fields, we recently demonstrated that gigahertz-frequency lattice strain resonant with the $m_s$= +1 to -1 spin state splitting can also be used to drive spin transitions.\footnote{E. R. MacQuarrie {\it et al.} Phys. Rev. Lett. 111, 227602 (2013)} We present coherent spin control over NV center ensembles with a bulk-mode mechanical microresonator that generates large amplitude ac stress within the diamond substrate. Using these structures, we mechanically drive coherent Rabi oscillations between the -1 and +1 states. We also accurately model the Rabi dephasing with a combination of a spatially inhomogeneous mechanical driving field and magnetic noise from a fluctuating spin bath. Understanding mechanically driven dynamics in spin ensembles could have applications in sensing and quantum optomechanics where interactions can be enhanced by the number of spins. Moreover, these results demonstrate coherent mechanical control of the magnetically forbidden -1 to +1 spin transition, thus closing the loop on NV center ground state spin control and enabling the creation of a coherent $\Delta$-system within the NV center ground state. [Preview Abstract] |
Tuesday, March 3, 2015 10:48AM - 11:00AM |
F31.00013: Recursive polarization of nuclear spins in diamond at arbitrary magnetic field Daniela Pagliero, Abdelghani Laraoui, Jacob Henshaw, Carlos Meriles We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80\% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700