Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session D37: Focus Session: Semiconductor Qubits - Optically Addressed Dots and Impurities I |
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Sponsoring Units: GQI Chair: Thaddeus Ladd, HRL Laboratories Room: 212A |
Monday, March 2, 2015 2:30PM - 3:06PM |
D37.00001: Coherent Optical Control of Quantum Dots: Spin Qubits and Flying Qubits Invited Speaker: Alex Burgers Coherent control of solid-state qubits lies at the heart of most quantum information architectures. In quantum dots (QDs), optical fields are an attractive medium for qubit manipulation and readout. The entanglement between a QD spin qubit and an emitted photonic qubit allows for the transport of quantum information between distant quantum memories via decoherence resistant photon channels. I will present recent experimental work showing the entanglement between a single electron spin confined to an InAs QD and its spontaneously emitted photon. This entanglement is significant for the further development of quantum information technologies using QDs and forms the foundation of on-chip technologies using photonic crystal pathways. In addition, I will discuss on-going work on teleportation of information from a single photon generated in a spontaneous parametric down conversion (SPDC) process to a QD spin through intermediate interference between the SPDC photon and the dot's emitted photon. The ability to integrate two quantum information platforms is not only exciting in its own right, but this technique could allow for an entanglement swapping bridge between other matter-qubit (ions, NV centers, etc.) based quantum memories. [Preview Abstract] |
Monday, March 2, 2015 3:06PM - 3:18PM |
D37.00002: ABSTRACT WITHDRAWN |
Monday, March 2, 2015 3:18PM - 3:30PM |
D37.00003: Photon Statistics of Quantum Dot Resonance Fluorescence under the Influence of a Non-Resonant Laser Disheng Chen, Gary Lander, Cabot Zabriskie, Edward Flagg We study the statistical behavior of resonance fluorescence from self-assembled InAs quantum dots (QDs) as a function of the density of free charge carriers introduced by a HeNe laser. Second-order correlation measurements show bunching behavior that changes with HeNe laser power. Resonant photoluminescence excitation spectra indicate that the QD experiences discrete spectral shifts due to changes in the local charge environment. These spectral shifts, combined with tunneling of charges from the QD to nearby defects, provide an explanation of the bunching observed in the correlations. [Preview Abstract] |
Monday, March 2, 2015 3:30PM - 3:42PM |
D37.00004: Resonance Fluorescence Spectrum from a Quantum Dot Driven by a Periodically-Pulsed Laser Kumarsiri Konthasinghe, Manoj Peiris, Benjamin Petrak, Ying Yu, Zhichuan Niu, Andreas Muller We report the measurement of the spectrum of the light scattered near-resonantly by a quantum dot under excitation by a periodically-pulsed laser, i.e., a frequency comb. Even though the scattered light spectrum under monochromatic excitation, the ``Mollow triplet'', is well known, the resonance fluorescence spectrum under pulsed excitation has so far only been investigated theoretically. By using a high resolution Fabry-Perot interferometer and a stabilized mode-locked laser source we were able to measure the spectrum and second-order correlation function of the scattered light. In particular, the coherently and incoherently scattered light can be distinguished by virtue of the frequency comb scattering. The spectrum exhibits predicted features such as multiple sidebands when the pulse duration is long enough. In addition, Rabi oscillations are found to proceed with different phases for the two components of the scattered light. Satisfactory agreement is found between the experimental data and simulations when the effect of spectral diffusion is included [Preview Abstract] |
Monday, March 2, 2015 3:42PM - 3:54PM |
D37.00005: Magneto-photoluminescence study of InAs quantum dots emitting at 1150nm Laura Kinnischtzke, Yiming Lai, Antonio Badolato, Nick Vamivakas Self-assembled InAs/GaAs quantum dots are frequently designed to emit light in the range of 920-980nm, and the spectroscopic characterization of neutral and charged excitons in this range is well understood. We study the magnetic field dependence of low-temperature photoluminescence from InAs self-assembled quantum dots emitting close to 1 eV (1150 nm). The dots are incorporated into a field-effect device to map out the fine structure of charged and neutral excitons using magneto-photoluminescence spectroscopy in the Faraday geometry up to 7 Tesla. Previously developed models of Coulomb blockade and fine structure in InAs/GaAs QDs can be extended to measure the effective g-factor of the exciton complexes in these lower-energy quantum dots. [Preview Abstract] |
Monday, March 2, 2015 3:54PM - 4:06PM |
D37.00006: Dynamic nuclear polarization in self-assembled quantum dot by quadrupole effect Bao Liu, Ping Wang, Wen Yang We apply the recently developed theory of dynamic nuclear polarization to analyze a new nuclear polarization mechanism assisted by quadrupole interaction. This mechanism was proposed to explain a series of experimental observations in a self-assembled quantum dot. We find that although the steady state nuclear polarization agrees with previous works, the rate at which the nuclear spins are polarized is smaller by two orders of magnitude. [Preview Abstract] |
Monday, March 2, 2015 4:06PM - 4:18PM |
D37.00007: Long-range two-qubit gate between nuclear spins in diamond mediated via an optical cavity Adrian Auer, Guido Burkard Nitrogen-vacancy (NV) centers in diamond represent a promising possibility for a solid-state based realization of a qubit due to their excellent electron- and nuclear-spin coherence properties. Single-qubit gates for the nitrogen nuclear spin have been implemented [1]. Here, we extend an earlier proposal [2] for cavity-mediated coupling between NV electron spins and develop a scheme to implement a universal two-qubit gate between $^{14}$N or $^{15}$N nuclear spins. By virtually exciting a single NV center with an external laser field, a photon can be scattered into a surrounding cavity; we show that this process depends on the spin state of the nitrogen nucleus. For the two-qubit gate, we consider two NV centers coupled to a common cavity mode and each being excited individually. Virtual cavity excitation can then mediate an effective interaction between the NV nuclear spin qubits, generating a controlled-$\textit{Z}$ gate. Operation times for the gate implementation are found to be below 100 nanoseconds, which is orders of magnitude faster than the decoherence time of nuclear spin qubits in diamond.\\[4pt] [1] S.~Sangtawesin \textit{et al.}, Phys.~Rev.~Lett.~\textbf{113}, 020506 (2014).\newline [2] G.~Burkard and D.~D.~Awschalom, arXiv:1402.6351. [Preview Abstract] |
Monday, March 2, 2015 4:18PM - 4:30PM |
D37.00008: Quantum error correction with nuclear spins in diamond Tim Hugo Taminiau, Julia Cramer, M. A. Rol, Norbert Kalb, V. V. Dobrovitski, Ronald Hanson Quantum error correction is essential for large-scale quantum information processing. By encoding a quantum state in an entangled state of multiple qubits errors can be detected and corrected without obtaining information about the encoded state [1,2]. In this talk I will present quantum error correction based on spins in diamond. We used the electron spin of a nitrogen-vacancy centre to selectively initialize, control and read out multiple carbon-13 nuclear spins in the surrounding spin bath [3]. With these spin we implemented a three-qubit quantum-error-correction protocol and demonstrated the robustness of the encoded state against applied errors [1]. Furthermore, I will discuss how working at cryogenic temperatures will make it possible to realize error correction based on projective multi-qubit parity measurements [4], as envisioned in most modern error correction codes. \\ {} [1] T. H. Taminiau et al., Nature Nanotech. 9, 171 (2014) [2] G. Waldherr et al., Nature 506, 204 (2014) [3] T. H. Taminiau et al., Phys. Rev. Lett. 109, 137602 (2012) [4] W. Pfaff et al., Nature Phys. 9, 29 (2013) [Preview Abstract] |
Monday, March 2, 2015 4:30PM - 4:42PM |
D37.00009: The spin state depolarization induced by charge state conversion of Nitrogen Vacancy center in diamond Xiangdong Chen The negatively charged nitrogen vacancy center (NV$^{-}$) in diamond possesses the optically polarized electron spin state, which enables it to be used for quantum computation and metrology. In this work, we showed the depolarization of NV$^{-}$ electron spin state induced by charge state conversion. Both the polarization and depolarization of spin state exist during the two-photon charge state conversion process. The fidelity of NV$^{-}$ spin state initialization is decreased with the laser power. Due to the charge state conversion induced spin state depolarization, the fluorescence intensity of NV center shows a decrease with high laser power. Our work provide the information to further understand the photon induced charge state conversion, and can help to optimize the application based on NV center. [Preview Abstract] |
Monday, March 2, 2015 4:42PM - 4:54PM |
D37.00010: ABSTRACT MOVED TO L14.00013 |
Monday, March 2, 2015 4:54PM - 5:06PM |
D37.00011: Perfect selective orientation of nitrogen vacancy centers in diamond Takahiro Fukui, Yuki Doi, Takehide Miyazaki, Yoshiyuki Miyamoto, Hiromitsu Kato, Tsubasa Matsumoto, Toshiharu Makino, Satoshi Yamasaki, Ryusuke Morimoto, Norio Tokuda, Mutsuko Hatano, Yuki Sakagawa, Hiroki Morishita, Toshiyuki Tashima, Shinji Miwa, Yoshishige Suzuki, Norikazu Mizuochi Nitrogen-vacancy centers in diamond are equally aligned along one of four axes. The precise control of the NV axis is significant for enhancement of a magnetic-field sensitivity. We investigated the alignment of NV centers in a (111)-CVD diamond by optically detected magnetic resonance. more than 99 {\%} of the NV centers is aligned along the [111]-axis [1]. Simulation results using first-principles energetics also demonstrate that the preferential alignment is caused by the nitrogen-atom lone-pair in the [111] direction [2]. We show preliminary results of the preferential alignment of NV centers made by an ion-implantation. Note that other groups reported such an alignment of NV centers [3]. we acknowledge financial support by SCOPE, JST-CREST, KAKENHI, and NICT programs. [1] T. Fukui, et al., Appl. Phys. Express \textbf{7}, 121202 (2014). [2] T. Miyazaki, T. Fukui, et al., arXiv: 1409. 2573 (2014). [3] J. Michl, et al., Appl. Phys. Lett. \textbf{104}, 102407 (2014); M. Lesik, et al., Appl. Phys. Lett. \textbf{104}, 113107 (2014). [Preview Abstract] |
Monday, March 2, 2015 5:06PM - 5:18PM |
D37.00012: Control of multi-qubit nodes for diamond quantum networks Julia Cramer, M. Adriaan Rol, Norbert Kalb, Viatcheslav V. Dobrovitski, Ronald Hanson, Tim H. Taminiau Quantum networks consisting of multiple connected nodes enable distributed quantum computation and secure quantum communication. Such networks require multi-qubit quantum registers that can be remotely linked. In this work we demonstrate initialization and control of multiple qubits in a nitrogen-vacancy (NV) node in diamond. We use the NV electron spin as an ancillary qubit to detect individual weakly coupled nuclear carbon-13 spins and construct high-fidelity quantum gates [1]. With these gates we show initialization, control and entanglement of multiple nuclear spins. Combined with projective measurements of the NV electron spin [2] and long-range entanglement through optical channels [3] at cryogenic temperatures, this work paves the way for communication between distant quantum nodes via ancillary qubits while preserving complex entangled states in quantum memories within the nodes. \\[4pt] [1] T.H. Taminiau et al., Nature Nanotech. 9, 171 (2014)\\[0pt] [2] L. Robledo et al., Nature 477, 547 (2011)\\[0pt] [3] W. Pfaff et al., Science 345, 532-535 (2014) [Preview Abstract] |
Monday, March 2, 2015 5:18PM - 5:30PM |
D37.00013: Quantum theory of nuclear spin dynamics in optically pumped diamond nitrogen-vacancy center Ping Wang, Wen Yang We develop a microscopic theory for a variety of nuclear spin dynamics such as dephasing, relaxation, squeezing, and narrowing due to the hyperfine interaction with an optically pumped nitrogen vacancy center. The first-order result justifies the nonlinear Hamiltonian for nuclear spin squeezing [M. S. Rudner et al., Phys. Rev. Lett. 107, 206806 (2011)]. The second-order result provides a reasonable explanation to the experimentally observed 13C nuclear spin bath narrowing [E. Togan et al., Nature 478, 497 (2011)]. [Preview Abstract] |
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