Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session P49: Semiconductor Single Photon Sources |
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Sponsoring Units: GQI DCMP Chair: Andrey A. Kiselev, HRL Laboratories Room: 396 |
Wednesday, March 15, 2017 2:30PM - 2:42PM |
P49.00001: Phase-tuned entangled state generation between distant spin qubits Robert Stockill, Megan Stanley, Lukas Huthmacher, Claire Le Gall, Aaron Miller, Edmund Clarke, Maxime Hugues, Clemens Matthiesen, Mete Atature In addition to being one of the most intriguing features of quantum mechanics, distant entanglement provides the unique advantage to networks constructed from coherent, optically connected qubits. Candidates of particular interest for distributed quantum networks are single spins confined to optically-active quantum dots. The strong, coherent optical transitions in these systems provide an ultrafast interface between the ground state spin and well-defined optical modes. We use this interface to distribute entanglement between two electron spins resident in separate quantum dots via the measurement of a single photon [1]. Our minimal heralding scheme and the strength of the optical transitions permits state creation at an 8-kHz rate, the highest reported for nonlocal qubits. We recover a Bell-state fidelity of $61.6\pm2.3\%$, determining the non-classicality of the shared state. We demonstrate arbitrary state creation through the phase of our projective measurement. The state distribution reported here establishes spins in optically-active quantum dots as a high-frequency host for controllable nonlocal states. [1] Cabrillo, C. et al., 1999 PRA, 59, 1025-1033 [Preview Abstract] |
Wednesday, March 15, 2017 2:42PM - 2:54PM |
P49.00002: Solid-state ensemble of highly entangled photon sources at rubidium atomic transitions Michael Zopf, Robert Keil, Yan Chen, Bianca Höfer, Jiaxiang Zhang, Fei Ding, Oliver G. Schmidt Semiconductor InAs/GaAs quantum dots grown by the Stranski-Krastanov method are among the leading candidates for the deterministic generation of polarization entangled photon pairs. Despite remarkable progress in the last twenty years, many challenges still remain for this material, such as the extremely low yield (< 1\% quantum dots can emit entangled photons), the low degree of entanglement, and the large wavelength distribution. Here we show that, with an emerging family of GaAs/AlGaAs quantum dots grown by droplet etching and nanohole infilling, it is possible to obtain a large ensemble (close to 100\%) of polarization-entangled photon emitters on a wafer without any post-growth tuning. Under pulsed resonant two-photon excitation, all measured quantum dots emit single pairs of entangled photons with ultra-high purity, high degree of entanglement (fidelity up to F=0.91, with a record high concurrence C=0.90), and ultra-narrow wavelength distribution at rubidium transitions. Therefore, a solid-state quantum repeater - among many other key enabling quantum photonic elements - can be practically implemented with this new material. [Preview Abstract] |
Wednesday, March 15, 2017 2:54PM - 3:06PM |
P49.00003: Strongly correlated photons from single quantum dots in polarization degenerate micropillar cavities J. A. Frey, H. Snijders, J. Norman, E. C. Langman, M. P. Bakker, A. Gossard, J. E. Bowers, M. P. van Exter, W. Loffler, D. Bouwmeester A self-assembled quantum dot embedded in an oxide tapered microcavity forms a compact and robust cavity quantum electrodynamics (CQED) system for applications in quantum information science, such as, single and entangled photon sources, quantum repeaters, and photonic quantum gates. In a polarization degenerate microcavity, a quantum dot can couple to both polarizations of a cavity mode. This enables polarization-based filtering of photons that interacted with the quantum dot. We show that this enables transforming coherent laser light into a stream of strongly correlated photons with a record high g$^{\mathrm{2}}$(0) in the solid state [1]. Further, by comparison to numerical simulations, we obtain first indication of Jaynes-Cummings physics in the weak-coupling regime of CQED. Polarization degeneracy is complicated by inherent imperfections in the fabrication of the micropillar cavities by residual ellipticity and strain. The splitting of the polarized modes must be fine-tuned in some way, usually involving tuning of birefringence through strain. As a convenient alternative we show first results on electro-optic tuning through a Schottky gate over one of the cavity mirrors. [1] Nat. Commun. 7, 12578 (2016). [Preview Abstract] |
Wednesday, March 15, 2017 3:06PM - 3:18PM |
P49.00004: Tuning the linewidth of spin-flip Raman emission from a quantum dot molecule Brennan C. Pursley, S. G. Carter, M. Kim, C. S. Kim, S. E. Economou, M. Yakes, A. S. Bracker, D. Gammon Single quantum dots have many promising attributes for quantum information due to their bright emission, indistinguishable single photons, and robust solid state engineering. Quantum dot molecules, comprised of two quantum dots with tunnel coupled carriers, should retain the benefits of single quantum dots while offering an array of novel physics. When each dot is charged with a single electron, the coupled spin ground states form a singlet and three degenerate triplets. The singlet and spin-0 triplet share an excited state which forms a lambda system allowing for spin-flip Raman emission---a source of tunable and potentially indistinguishable photons. Here we perform high resolution spectroscopy of the Raman emission and determine the processes that control the linewidth. By analyzing the effects of cotunneling to the electron reservoir and line wandering as a function of bias, we extract their relative importance to the lineshape. We have also demonstrated that using a pulsed laser can increase the linewidth of Raman emission to match that of the pulse, which has the potential to control the bandwidth of emitted photons and overcome detrimental line-broadening effects. [Preview Abstract] |
Wednesday, March 15, 2017 3:18PM - 3:30PM |
P49.00005: Charging dynamics of single InGaAs quantum dots under resonant excitation Gary Lander, Disheng Chen, Glenn Solomon, Edward Flagg We investigate the rates of charge state fluctuation in single InGaAs quantum dots under resonant excitation and with an additional low-power above-band laser. Resonant excitation of either a neutral or charged quantum dot can cause a transition to the opposite charge state, which greatly diminishes the fluorescence and reduces a dot's suitability to act as an efficient photon source. A counter to this effect is a low-power above-band laser that supplies the local charge environment with extra electrons and holes in the bulk GaAs. These charge carriers can be captured by either a charged quantum dot, resulting in neutralization and allowing resonant excitation of the exciton state, or a neutral quantum dot, allowing resonant excitation of the trion state. We characterize as a function of laser power both the steady-state regime and the time-dependent dynamics of the system by modulating either the above-band or resonant laser. The time-resolved fluorescence is recorded and fit with a population evolution model to extract the charging and discharging rates of both the trion and neutral exciton. [Preview Abstract] |
Wednesday, March 15, 2017 3:30PM - 3:42PM |
P49.00006: Polarization-dependent interference of coherent scattering from orthogonal dipole moments of a resonantly excited quantum dot Disheng Chen, Gary Lander, Glenn Solomon, Edward Flagg An unconventional line-shape that depends on the detection polarization is observed in the resonant photoluminescence excitation (RPLE) spectrum of a neutral InGaAs quantum dot. We investigate this phenomenon by performing polarization-dependent RPLE measurements and simulating the measured spectra with a 3-level quantum model. Our analysis indicates that interference between coherent scattering from the two fine structure split exciton states is the key to understanding this phenomenon. The RPLE spectra taken at multiple polarizations enable us to extract the steady-state coherence between the two exciton states. There are only two relatively unrestrictive conditions on observing this phenomenon: non-degenerate states with orthogonal dipole moments. Such requirements are naturally met in many solid state systems, for example, quantum dots, NV centers in diamond, and possibly defect-bound states in 2-D materials. [Preview Abstract] |
Wednesday, March 15, 2017 3:42PM - 3:54PM |
P49.00007: Robust Solid State Quantum System Operating at 800 K. Mehran Kianinia, Sherif Abdulkader Tawfik, Blake r, Toan Trong Tran, Mike Ford, Igor Aharonovich, Milos Toth Realization of Quantum information and communications technologies requires robust, stable solid state single photon sources. However, most existing sources cease to function above cryogenic or room temperature due to thermal ionization or strong phonon coupling which impede their emissive and quantum properties. Here we present an efficient single photon source based on a defect in a van der Waals crystal that is optically stable and operates at elevated temperatures of up to 800 K. The quantum nature of the source and the photon purity are maintained upon heating to 800 K and cooling back to room temperature. Our report of a robust high temperature solid state single photon source constitutes a significant step to-wards practical, integrated quantum technologies for real-world environments. [Preview Abstract] |
Wednesday, March 15, 2017 3:54PM - 4:06PM |
P49.00008: Tunable-correlation phenomenon of single photons emitted from a self-assembled quantum dot Shang Yu, Jian-Shun Tang, Yi-Tao Wang, Chuang-Feng Li, Guang-Can Guo Deterministic single-photon source plays a key role in the quantum information technology. Thus, research on various properties of such kind of light source becomes a quite necessary task. In this work, we experimentally observe that the second-order correlation properties of single photons can be continuously tuned from pulsed excitation configuration to continuous-wave excitation configuration under the near resonant photoluminescence excitation. By increasing the power of pulsed excitation laser, the effective excitation time of quantum dot can be extended with assistance of the defect states, and more continuous-wave excitation characteristics will gradually appear in the second-order correlation functions. This abnormal power-induced tunable-correlation mechanism can affect the temporal property of the single-photon source but maintain its antibunching property. [Preview Abstract] |
Wednesday, March 15, 2017 4:06PM - 4:18PM |
P49.00009: A High-Purity Single Photon Emitter in Aluminum Nitride Benjamin Lienhard, Tsung-Ju Lu, Kwang-Yong Jeong, Hyowon Moon, Ava Iranmanesh, Gabriele Grosso, Dirk Englund Highly efficient, on-demand, and robust single photon emitters (SPEs) are essential to many areas of quantum information processing. Over the past decade, color centers in solids have emerged as excellent SPEs and have also been shown to provide optical access to internal spin states. Color centers in diamond and silicon carbide are among the most intensively studied SPEs. Recently, other cost-efficient wide-bandgap materials have become attractive as potential host materials. Theoretical calculations show that aluminum nitride (AlN) with a bandgap of 6.015 eV can serve as a stable environment for well isolated SPEs with optically accessible spin states. Here, we report on a room-temperature SPE that emits in the visible spectrum. The SPEs are hosted by AlN thin-films on sapphire substrates. Annealing treatments enable the control of their photostability and density. These SPEs are highly efficient and emit single photons up to 95\% purity. The presence of high-purity SPEs, along with the good optomechanical properties, makes AlN a promising candidate for quantum information processing. [Preview Abstract] |
Wednesday, March 15, 2017 4:18PM - 4:30PM |
P49.00010: Photon Correlation Measurements on Vertically Coupled InAs/GaAs Quantum Dots Thushan Wickramasinghe, Venkata Thota, Mauricio Garrido, Eric Stinaff, Alan Bracker, David Gammon Quantum dots have shown fascinatingly unique properties that differ significantly from bulk material and their compatibility with semiconductor manufacturing makes them a candidate for quantum communication technology based optoelectronic devices. Coupled quantum dots (CQDs), formed by growing two sequential layers of dots with a separation of a few nanometers, results in a coherent molecular wave function that extends over the constituent dots providing a way to engineer the wave function. This allows for interesting configurations such as a bi-exciton state with a direct (electron and hole within the same dot) and indirect (electron and hole in different dots) transition. Emission from such a state will produce correlated, and possibly even entangled, photon pairs. We will present photon correlation measurements, using a Hanbury Brown and Twiss set up with single photon counting modules, on In$_{\mathrm{1-X}}$Ga$_{\mathrm{X}}$As CQDs embedded inside a GaAs based Schottky diode structure. Results from individual exciton transitions as well as bi-exciton transitions will be presented indicating such molecular-like excitons may provide a means for on-demand correlated, and potentially, entangled photon generation. [Preview Abstract] |
Wednesday, March 15, 2017 4:30PM - 4:42PM |
P49.00011: Bulk InAlAs(111)A as a novel material system for pure, single photon emission Paul J. Simmonds, S. Unsleber, M. Deppisch, M. Vo, C. Schneider, S. H\"ofling, C. M. Krammel, P. M. Koenraad, C. D. Yerino, M. L. Lee Certain protocols for quantum cryptography rely on a single photon source.\footnote{Shields, Nat. Phot. 1, 215 (2007)} Semiconductor quantum dots (QDs) are an attractive candidate for single photon generation: QDs can be incorporated into scalable cavity/waveguide structures, and QD quantum key distribution has already been demonstrated.\footnote{Rau et al., New J. Phys. 16, 043003 (2014)} Growth of III-V QDs is well established, but very close control is required. QD density/size are dramatically affected by small changes in growth parameters, which is a challenge for QD uniformity. In contrast, we present a material system with a remarkably straightforward growth process, which delivers single photon emission. We see spectrally sharp emission lines from bulk InAlAs grown on InP(111)A. Via cross-sectional STM and $k\cdot p$ simulations, we identify excitons in indium-rich nanoclusters as the origin of these spectral features. In-rich regions form spontaneously during growth via nanoscale InAlAs phase-segregation. Nanocluster emission has median linewidth 137 eV, and fine structure splitting 28 eV. We confirm on-demand emission of pure, single photon emission, with 2nd-order correlation values $g^{(2)} = 0.05_{-0.05}^{+0.17}$ (CW), and $0.24 \pm 0.02$ (triggered). [Preview Abstract] |
Wednesday, March 15, 2017 4:42PM - 4:54PM |
P49.00012: Abstract Withdrawn
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Wednesday, March 15, 2017 4:54PM - 5:06PM |
P49.00013: Spectrally Uniform Quantum Dot Single Photon Emitter Array for Integrated Nanophotonics: Electronic Structure and Optical Properties Jiefei Zhang, Swarnabha Chattaraj, Siyuan Lu, Anupam Madhukar Recently we proposed a new paradigm for nanophotonic quantum information processing(QIP) systems comprising on-chip single quantum dots (SQD) as single photon source (SPS) array integrated with light manipulating elements(LME) [1]. To this end we demonstrated an ordered array of spectrally uniform InGaAs mesa top SQDs (MTSQD) as on-chip SPSs [1, 2] that have spectral uniformity an order of magnitude better than traditional island QDs and show triggered single photon emission at 77.4K. In this talk we will present low temperature photoluminescence (PL) and PL excitation studies showing that the first excited states are, for electrons and heavy holes, respectively \textasciitilde 40meV and \textasciitilde 10meV from the ground states. Thermally mediated carrier escape to the first excited states is revealed from temperature dependent PL. Additionally, results on low temperature and polarization dependent single photon emission (g$^{\mathrm{(2)}}$(0)) will be reported. Such MTSQD arrays, after a planarizing overgrowth, are ideally suited for monolithic integration with appropriate LMEs for applications towards on-chip QIP systems. [1] J. Zhang et.al, arXiv:1609.00068 (2016). [2] J. Zhang et.al., Jour. Vac. Sc. Tech. B32, 02C106 (2014). [Preview Abstract] |
Wednesday, March 15, 2017 5:06PM - 5:18PM |
P49.00014: Quantum Dot Single Photon Emitter Array Integrated with Dielectric Nanoantenna-Waveguide: Simulation of Multifunctional Optical Response Swarnabha Chattaraj, Jiefei Zhang, Siyuan Lu, Anupam Madhukar Recently we proposed a new paradigm for nanophotonic quantum information processing (QIP) systems comprising on-chip single photon source (SPS) array integrated with light manipulating elements (LMEs) that use collective Mie resonance in subwavelength sized dielectric building blocks (DBBs) [1]. To this end we demonstrated an ordered array of spectrally uniform InGaAs mesa top single quantum dots (MTSQDs) as on-chip SPSs [1, 2] that exhibit spectral uniformity an order of magnitude better than conventional island QDs and show triggered single photon emission at 77.4K. With a planarizing overgrowth on such a MTSQD array the system is ideally suited for lithographic fabrication of the LMEs. In this talk we will present simulation results of DBB based nanoantenna-waveguide LME that produces Purcell enhancement of \textasciitilde 10 and guides and propagates the emitted photons losslessly, all using the collective magnetic dipole modes of the DBBs. Additionally, explorations of on-chip beam-splitting in the DBB arrays will be presented. Such MTSQD-DBB integrated unit can serve as a building block for complex hierarchical nanophotonic QIP systems. [1] J. Zhang et. al, arXiv:1609.00068 (2016). [2] J. Zhang et. al., Jour. Vac. Sc. Tech. B32, 02C106 (2014). [Preview Abstract] |
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