Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session Y15: Defect Center Qubits |
Hide Abstracts |
Sponsoring Units: DQI DMP Chair: Sophia Economou Room: LACC 304C |
Friday, March 9, 2018 11:15AM - 11:27AM |
Y15.00001: Hybrid Diamond-Silicon Carbide Color Center Photonics Marina Radulaski, Yan-Kai Tzeng, Jingyuan Linda Zhang, Konstantinos Lagoudakis, Hitoshi Ishiwata, Constantin Dory, Kevin Fischer, Yousif Kelaita, Shuo Sun, Peter Maurer, Kassem Alassaad, Gabriel Ferro, Zhi-Xun Shen, Nicholas Melosh, Steven Chu, Jelena Vuckovic Diamond color centers are excellent quantum emitters for applications in quantum and classical optical networks. However, the incorporation of diamond color centers into photonic devices with arbitrary geometry has been an outstanding challenge. Interfacing diamond with cubic silicon carbide (3C-SiC) grown on a silicon wafer is a promising hybrid approach to this problem. Not only do silicon carbide optical properties resemble diamond’s, but the underlying silicon can be undercut to realize freestanding designs. We utilize chemical vapor deposition and reactive ion etching to incorporate color center-rich nanodiamond with fabricated silicon carbide microdisk resonators. The process is scalable and features a preferential positioning of emitters relative to the resonant mode needed to achieve Purcell enhancement. We demonstrate up to a five-fold resonant enhancement of diamond silicon-vacancy and chromium-related color center emission. |
Friday, March 9, 2018 11:27AM - 11:39AM |
Y15.00002: Towards a coherent spin-phonon interface in diamond Srujan Meesala, Michael Burek, Cleaven Chia, Nayera El-Sawah, Young-Ik Sohn, Marc-Antoine Lemonde, Mikhail Lukin, Peter Rabl, Marko Loncar Mechanical vibrations interact with a variety of quantum systems, and can serve as a channel between qubits with different physical realizations. Here, we describe our experimental efforts towards a coherent interface between phonons and a spin qubit. The spin qubit of our choice is the silicon-vacancy (SiV) color center in diamond. A combination of the large response of the SiV spin to oscillating strain from phonons, and the confinement of relevant phonons in compact mechanical modes provided by optomechanical crystals (OMCs) will allow strong coupling with MHz single-phonon coupling rates. Towards this end, we establish the strain response of the SiV spin using a nanoscale cantilever, and measure a large strain susceptibility of 100 THz/strain. In parallel, we demonstrate high quality-factor (105) GHz frequency mechanical modes in diamond OMCs. With current experimental parameters, this platform will allow laser cooling of the mechanical resonator at 4 K, and phonon-mediated two-qubit gates as well as quantum non-linearities for single phonons at mK temperatures. |
Friday, March 9, 2018 11:39AM - 11:51AM |
Y15.00003: Understanding and overcoming the barriers to room-temperature quantum computation in diamond Andrew Horsley, Sophie Stearn, Lachlan Öberg, Eric Huang, Neil Manson, Marcus Doherty NV spin clusters in diamond, consisting of NV centres coupled to nearby nuclear spins, form one of the few platforms suitable for room-temperature quantum computing. We present an overview of our work on understanding and overcoming the barriers for large scale quantum computation with NV spin clusters: (1) A critical limit on qubit initialisation and readout fidelities is nuclear relaxation induced by the NV electron flipping between its ground and optically excited states. Certain lattice sites are relatively immune to this effect. We perform ab initio modelling of the NV optical-spin dynamics to estimate gate fidelities for different 13C sites. (2) The density of nuclear spin resonances in NV spin clusters requires careful design of control pulses to avoid erroneous driving of qubits. We are designing fast pulses that minimise erroneous driving, using both analytical and numerical techniques. (3) The major barrier to scalable diamond quantum computing remains on-chip networking of NV spin clusters. We have recently proposed a new approach, and our follow-up modelling has shown that nanowires should be able to guide coherent electron transport between defects. We have also identified possible quantum transport techniques with the potential to greatly enhance transport fidelity. |
Friday, March 9, 2018 11:51AM - 12:03PM |
Y15.00004: Experimental realization of entanglement sudden death and rebirth at room temperature in diamond Fei Wang, Panyu Hou, Yuanyuan Huang, Wengang Zhang, Luming Duan We experimentally demonstrate the dynamics of entangled quantum states under different noise environments using the electron-nuclear spin system in diamond operating at room temperature. We use multi-pulse sequences that dynamically suppress or resonantly amplify the interactions with $^{13}C$ spin bath to control the local environment of the electron spin. By way of the concurrence, we show that dissipation of electron spin into the spin bath leads to sudden death of entanglement. Furthermore, by selectively amplifying certain part of the interactions, we observe rebirth of entanglement after the sudden death. |
Friday, March 9, 2018 12:03PM - 12:15PM |
Y15.00005: Proposal for a spin network using a qubit in diamond-peptide unit cell Lukas Schlipf, Thomas Oeckinghaus, Kebiao Xu, Durga Dasari, Andrea Zappe, Felipe Fávaro de Oliveira, Bastian Kern, Mykhailo Azarkh, Malte Drescher, Markus Ternes, Klaus Kern, J. Wrachtrup, Amit Finkler Synthetic peptides can nowadays be custom-tailored to one's needs to the extent that it is possible to determine their exact length and structure. Using such rather simple molecules, we propose using them, together with a qubit, in the form of a single nitrogen-vacancy center in diamond being the read-out platform, as the basic unit cell in a conceivable molecular quantum spin network. |
Friday, March 9, 2018 12:15PM - 12:27PM |
Y15.00006: An integrated diamond nanophotonics platform for quantum optics Ruffin Evans, Denis Sukachev, Christian Nguyen, Mihir Bhaskar, Alp Sipahigil, Bartholomeus Machielse, Grace Zhang, Michael Burek, Marko Loncar, Mikhail Lukin Solid-state quantum-emitters with long spin coherence times and strong interactions with single-photons could form the building blocks of a quantum network. Unique among solid-state systems, silicon-vacancy (SiV) color centers in diamond can address both of these challenges. First, we place single SiV centers in diamond nanophotonic crystal cavities and demonstrate a single-atom cooperativity greater than 10, realizing strong atom-photon interactions that are nonlinear at the single-photon level. Using this platform, we demonstrate entanglement generation and two-SiV interactions mediated by the cavity mode. Finally, we improve the spin coherence time to greater than 13 milliseconds by cooling the system to below 100 mK. These results enable the realization of gates between multiple atoms and optical photons in solid-state devices. |
Friday, March 9, 2018 12:27PM - 12:39PM |
Y15.00007: Experimental realization of a universal set of adiabatic quantum gates with NV center in diamond Yuanyuan Huang, Yukai Wu, Fei Wang, Wengang Zhang, Xinxing Yuan, Panyu Hou, Luming Duan To realize quantum computer, a universal set of quantum logic gates is the basic requirement. Besides commonly used dynamical way, the geometric approach is recommended for its advantage of intrinsically noise-resilience feature. Experimental realization of a universal set of geometric quantum gates have already been reported with solid-state spins in nitrogen-vacancy diamond using non-adiabatic holonomies. However, non-adiabatic process is somewhat constrained in parameter value choosing, compared to adiabatic gates. Here, we realize a universal set of geometric quantum logic gates with adiabatic process in NV center system. The adiabatic gates are demonstrated to be robust against experimental control parameters for a wide range. These results suggest that any adiabatic geometric quantum algorithm can be realized in solid-state qubits, alongside its robustness to experimental parameters. |
Friday, March 9, 2018 12:39PM - 12:51PM |
Y15.00008: Optical, Spin, and Vibronic Properties of the Silicon Vacancy Defects in Silicon Carbide: Robust Spin-Photon Interfaces Oney Soykal, Joshua Young, Samuel Carter, Hunter Banks Over the past two decades, remarkable advances in material fabrication, optical control and spin read-out techniques have led to many successful demonstrations of quantum technologies based on defect spins in solids. Most recently, the silicon mono-vacancy defects in SiC have been identified as a promising candidate for spin-photon interfaces and quantum sensing applications. Recent optical studies of these defects have shown sharp zero-phonon-lines, high-fidelity spin read out, and long coherence times in millisecond time scales. As a next step in the development of realistic interfaces, we examine mechanisms such as vibronic coupling and Stark effect that are key to achieving spectrally narrow transitions and weak spectral diffusion. Our calculations reveal strong Jahn-Teller and pseudo Jahn-Teller effects in the V1, V1’, and V2 excited states that can alter the optical emission properties of these defects significantly. We also examine the electric field response of these excited states and develop a model for the photo-induced charge conversion. Our results are in good agreement with recent high-resolution optical spectroscopy of these defects and pave the way towards robust spin-photon interfaces. |
Friday, March 9, 2018 12:51PM - 1:03PM |
Y15.00009: Optical Properties of Single Silicon Vacancies in 4H-SiC Hunter Banks, Oney Soykal, Shojan Parvunny, Rachael Myers-Ward, D. Kurt Gaskill, Samuel Carter Defect states in wide bandgap materials have generated substantial interest in the past twenty years as promising systems for quantum information and quantum sensing because of their optical and spin properties. Recent work has found many promising SiC defect states, and so, coupled with the rapid maturation of SiC processing technology, SiC has become an attractive material for potential photonic and spintronic applications. The silicon vacancies in 4H-SiC are particularly interesting defects for near-infrared quantum optics, and we focus on V2 defect, which shows long spin coherence times even at room temperature. While much work has been performed on characterizing the spin properties of this defect, there are still many unknowns concerning the optical properties, particularly for single defects. We present high-resolution optical spectroscopy of single defects to better understand their emission properties and energy level structure. We show that the optical linewidths are narrow and resolve the fine structure of the excited state, which has significant differences compared to other commonly studied defects. This refined understanding of the optical transitions paves the way for precision quantum optical control of spins and photons. |
Friday, March 9, 2018 1:03PM - 1:15PM |
Y15.00010: Local cooling and control of a 2D nuclear spin lattice using NV centers in diamond Tamara Sumarac, Elana Urbach, Helena Knowles, Javier Sanchez-Yamagishi, Soonwon Choi, Igor Lovchinsky, Mikhail Lukin Two dimensional materials can provide a regular nuclear spin lattice, which makes them an excellent platform for studying interacting 2d spin dynamics. Traditional NMR techniques are not sensitive enough to measure small sample volumes of thin materials. Nitrogen vacancy (NV) centers in diamond can act as nanoscale magnetic field sensors with the ability to measure magnetic field created by very few nuclear spins. This makes the NV center an ideal probe for studying nuclear spin dynamics in 2d materials. In this experiment we use an NV center combined with an external radio frequency field to locally initialize, control and readout nuclear spin states inside hexagonal boron nitride (hBN), with a goal of developing a room temperature platform for studying many-body dynamics. |
Friday, March 9, 2018 1:15PM - 1:27PM |
Y15.00011: Quantum Sensing in the Physically Rotating Frame Alexander Wood, Emmanuel Lilette, Yaakov Fein, Viktor Perunicic, Lloyd Hollenberg, Robert Scholten, Andy Martin Quantum control of qubits in a physically rotating frame opens new opportunities to probe fundamental quantum physics, such as geometric phases, and can improve the sensitivity to detection of magnetic fields and rotations. We describe quantum measurement and control of nitrogen vacancy (NV) center qubits in a diamond rotating with a period comparable to the qubit electron spin coherence time T2. We use these rotating frame quantum sensors to detect rotationally-induced magnetic pseudo-fields acting on a bath of 13C nuclear spins surrounding the NV qubits (Nat Phys doi:10.1038/nphys4221). By rotating the diamond at rates comparable to the nuclear spin precession frequency (>100,000rpm) we can induce pseudo-fields large enough to cancel the conventional magnetic field for the nuclear spins while having minimal effect on the NV qubits. As well as highlighting the profound connection between magnetism and physical rotation, these results establish a novel way of controlling the nuclear spin bath surrounding the NV center. We discuss future work involving control of single NV qubits in a rotating diamond and possible improvements to metrology conferred by rapid sensor rotation. |
Friday, March 9, 2018 1:27PM - 1:39PM |
Y15.00012: Correlations of Continuous Weak Measurements on a Single Spin Matthias Pfender, Wang Ping, Nabeel Aslam, Wen Yang, Philipp Neumann, Renbao Liu, J. Wrachtrup In the last years, the nitrogen-vacancy defect in diamond has been established as an exceptional quantum sensor for physical quantities like magnetic and electric fields, capable of detecting the faint signal of only a few proton nuclear spin outside the diamond crystal [1]. In order to perform nuclear magnetic resonance spectroscopy (NMR) on such samples, a continuous readout scheme was developed by several different groups [2-4]. |
Friday, March 9, 2018 1:39PM - 1:51PM |
Y15.00013: Spectrally Resolved Second-Order Coherence of Nanoscale Plasmonic-NV Center Hybrids Matthew Feldman, Eugen Dumitrescu, Ethan Tucker, Jordan Hachtel, Matthew Chisholm, Philip Evans, Ilia Ivanov, Richard Haglund, Benjamin Lawrie We report colossal photon bunching of g(2)(0) ≈ 49 in the cathodoluminescence (CL) of neutral nitrogen vacancy (NV0) centers in nanodiamonds excited by an electron beam in a scanning transmission electron microscope. Spectrally filtered Hanbury Brown-Twiss (HBT) interferometry suggests that the bunching source is the phonon sideband, whereas no bunching is observed at the zero-phonon line. Our results are statistically consistent with fast phonon-mediated recombination dynamics, supported by validation between a Bayesian regression and a Monte-Carlo model of NV0 luminescence. We expand upon this work by leveraging well-developed nanofabrication techniques to fabricate hybrid quantum systems of NV centers coupled to surface plasmon polaritons (SPPs). The semi-classical dynamics of these systems will be estimated by finite difference time domain simulations to inform a Jaynes-Cummings model. The photon statistics of a multi-quantum emitter system coupled to SPPs will be characterized via HBT interferometry of the CL and photoluminescence of said systems. |
Friday, March 9, 2018 1:51PM - 2:03PM |
Y15.00014: Solid-state electron spin lifetime limited by phononic vacuum modes Thomas Astner, Johannes Gugler, Johannes Majer, Peter Mohn, Jörg Schmiedmayer, Stefan Putz, Andreas Angerer The nitrogen-vacancy (NV) center in diamond is important for applications in quantum technologies since it possesses long lifetimes (T1) and coherence times (T2). However, applications requiere knowledge of spin environment interaction. |
Friday, March 9, 2018 2:03PM - 2:15PM |
Y15.00015: Coherence properties of shallow donors in ZnO Xiayu Linpeng, Maria Viitaniemi, Yusuke Kozuka, Cameron Johnson, Joseph Falson, Atsushi Tsukazaki, Masashi Kawasaki, Kai-Mei Fu The donor system in ZnO is a promising potential qubit for spin-based quantum information processing. It has similar advantages as the well-studied phosphorus donors in Si, i.e. high homogeneity, long coherence time, and strong donor nucleus-electron interaction, with the additional advantage that ZnO donors are optically coupled to donor-bound excitons. Here we present optical measurements of the Ga donor electron spin T1, T2*, and T2. We find the longitudinal spin relaxation time T1 is inversely proportional to the external magnetic field with a relationship ~B-3.5. The longest T1 we measure is ~0.1 s at 2.5 T. Due to the B-3.5 relationship, we expect T1 will exceed 1 s at fields lower than 1 T. We measure a T2* of ~20 ns and a spin echo decoherence time T2 of ~30 μs, which may be limited by instantaneous diffusion due to the high donor concentration (~1017 cm-3) or the spectral diffusion due to flip-flop of the surrounding Zn67 nuclear spins (4.1% of natural Zn). We describe these experiments as well as present a path toward single Zn donor isolation and increased coherence times. |
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