Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session F65: Defects and Dopants in Bulk Materials II |
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Sponsoring Units: DMP Chair: Jinkyoung Yoo Room: Mile High Ballroom 4F |
Tuesday, March 3, 2020 8:00AM - 8:12AM |
F65.00001: High-Q Nanophotonic Resonators on Diamond Membranes using Atomic Layer Deposition TiO2 Amy Butcher, Xinghan Guo, Robert Shreiner, Kai Hao, Alexander A High Nanophotonic resonators are critical elements in solid state quantum networks, as they enable individual optical photons to interact with quantum spin states. In diamond, current techniques to fabricate these devices often introduce significant surface roughness and lattice strain, which limit performance and scalability. Using atomic layer deposition of TiO2, we developed a nanophotonic fabrication platform that avoids substrate etching while retaining the potential for high-cooperativity interfacing with color centers in thin diamond membranes. The resulting devices are exceptionally smooth and can be built on arbitrary substrates. In this work, we fabricated ring resonators and 1D photonic crystal cavities with quality factors exceeding 104 and demonstrated our platform’s potential for quantum networking applications on diamond. |
Tuesday, March 3, 2020 8:12AM - 8:24AM |
F65.00002: Single crystal diamond membranes for quantum networking and sensing Xinghan Guo, nazar delegan, Amy Butcher, David Awschalom, Joseph P Heremans, Alexander A High Atomic defects in single crystal diamond, such as nitrogen vacancy centers and silicon vacancy centers, are promising qubit candidates for quantum communication and quantum sensing applications. However, it is difficult to fully utilize their advantages in bulk diamond due to its high refractive index and limited nanofabrication methods. Therefore, to allow better integration flexibility of color centers while maintaining their coherence properties, we developed a process to create high quality, atomically smooth, large-scale single crystal diamond membranes that can be placed on any carrying wafers. Herein we will present the fabrication steps in detail, including He+ implantation, CVD overgrowth, electrochemical etching, flipping, transfer, and backside etching. Additionally, recent progress related to the integration of these diamond membranes will be demonstrated, namely, photonic cavity integration and creation of group IV and nitrogen vacancy defect centers, which would be beneficial in multi-qubit network, hybridized quantum systems, and quantum sensing. |
Tuesday, March 3, 2020 8:24AM - 8:36AM |
F65.00003: Single-shot readout of 171Yb:YVO ions embedded in a nanophotonic cavity Jonathan Kindem, Andrei Ruskuc, John G Bartholomew, Jake Rochman, Yan Qi Huan, Andrei Faraon Solid-state emitters coupled to photonic resonators are an attractive platform for building quantum light-matter interfaces required for scalable quantum networks. Rare-earth ions (REIs) in solids offer a promising system for such interfaces due to their long optical and spin coherence times at cryogenic temperatures, but harnessing these properties at the single ion level has proven to be challenging due to the inherently weak coupling of REIs with light. Here we present the initialization, coherent manipulation, and readout of individual ytterbium-171 ions embedded in a nanophotonic cavity fabricated directly in the yttrium orthovanadate (YVO) host crystal. These ions possess coupled electron-nuclear spin states that are first-order insensitive to magnetic field fluctuations, which allows for optical linewidths less than 1 MHz and spin coherence times greater than 30 ms. We show that Purcell enhancement in the nanophotonic cavity increases the optical emission rate by a factor of 120 and improves the cyclicity of the cavity-coupled optical transitions, which enables efficient initialization and conditional single-shot readout of the hyperfine spin state with fidelity greater than 95%. |
Tuesday, March 3, 2020 8:36AM - 8:48AM |
F65.00004: Spin dynamics of 171Yb:YVO ions embedded in a nanophotonic cavity Andrei Ruskuc, Jonathan Kindem, John G Bartholomew, Jake Rochman, Yan Qi Huan, Andrei Faraon Optically addressable spin qubits in solid state hosts are a promising platform for developing scalable quantum networks. We present results on a possible architecture based on single 171 Yb ions doped into yttrium orthovanadate. By coupling these ions to nanophotonic cavities we leverage the Purcell regime of cavity QED to enhance the weak, highly coherent optical transitions typically associated with rare earth ions thereby enabling detection and readout. |
Tuesday, March 3, 2020 8:48AM - 9:00AM |
F65.00005: An in-situ single photon source detection platform for deterministic nanometer resolution ion implantation Michael Titze, Kulturansingh Hooghan, Han Htoon, Edward S Bielejec Single photon sources (SPS) are of interest for usages from metrology to the basis of quantum communication, computation and sensing. SPS based on color centers in SiC and other wide band gap semiconductors such as hBN, diamond, etc. require the control over both the positioning as well as the number of optically active color centers. We have developed focused ion beam implantation using our nanoImplanter (nI) which allows spatial control to <50 nm and implantation down to single impurity atoms using counted ion implantation. However, the typical conversion efficiency from implanted impurity atom to optically active color center can range from <3% to >80% depending on the material and the implantation energy. For these low efficiency processes an in-situ technique to identity the creation of SPS is required. To this end we have designed an in-situ photoluminescence (PL) setup integrated into the nI allowing for detection of single photon emission during ion implantation. Using this PL setup in conjunction with a Hanbury Brown Twiss interferometer allows us to deterministically create and measure single color centers in a range of materials systems with nanometer resolution. |
Tuesday, March 3, 2020 9:00AM - 9:12AM |
F65.00006: Introduction of spin centers in single crystals of Ba2CaWO6-δ Mekhola Sinha, Tyler J. Pearson, Allen Scheie, Timothy Reeder, Hector K. Vivanco, Danna Freedman, William Adam Phelan, Tyrel McQueen Electronic spins are ideal qubit candidates both for their modularity and their ease of manipulation with microwave radiation. While fundamentally, T2, the spin-spin relaxation time, represents the functional operating time of a qubit, T1, the spin-lattice relaxation time, is ultimately the most restrictive parameter, as T1 represents the theoretical upper limit to T2. Design approaches to maximize T1 remain an open question. We report the coherence properties of W5+ spin centers in Ba2CaWO6-δ generated by oxygen vacancies. We characterized these defects by measuring the T1 and T2 times from T = 5 to 150 K. Correlation of the T1 lifetimes obtained from pulse EPR with phonon modes obtained from the heat capacity data quantifies the contribution of respective phonon modes to the spin-phonon coupling in the system. These results demonstrate that systematic defect generation in double perovskite structures can generate viable paramagnetic point centers for quantum applications. |
Tuesday, March 3, 2020 9:12AM - 9:24AM |
F65.00007: Purcell Enhancement of a Cavity-Coupled Single Spin Defect in Silicon Carbide Alexander Crook, Christopher Anderson, Kevin Miao, Alexandre Bourassa, Hope Lee, Sam L Bayliss, David O Bracher, Xingyu Zhang, Hiroshi Abe, Takeshi Ohshima, Evelyn L Hu, David Awschalom Silicon carbide (SiC) has recently been developed as a platform for optically addressable spin defects in the form of the neutral divacancy, most notably in the 4H polytype [1-3]. Here we present the Purcell enhancement of a single divacancy coupled to a photonic crystal cavity. We use a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5000. This corresponds to a Purcell factor of ~50 for a divacancy within the cavity mode and results in an increased photoluminescence into the zero-phonon line (ZPL) when on resonance with the cavity, as well as a shortened excited state lifetime. Additionally, we observe coherent control of the divacancy ground state spin inside of the cavity nanostructure. This system represents a major advance towards applications for the scalability of long-distance entanglement protocols using SiC that require the interference of indistinguishable photons from spatially separated single qubits. |
Tuesday, March 3, 2020 9:24AM - 9:36AM |
F65.00008: Engineering Light-Hole Quantum States in an Optically Active Group IV Low Dimensional System Anis Attiaoui, Simone Assali, Oussama Moutanabbir Hole spins have attracted a great deal of attention because of their reduced coupling to the nuclear spin bath. However, most of experimental investigations on 2D gas systems have so far focused on heavy-hole states (HH). This is attributed to the nature of the heterostructure currently exploited, where compressive strain lifts the valence band degeneracy and leaves HH states energetically well above the light-hole (LH) states. However, the ability to exploit LH states will be a powerful paradigm beneficial for quantum information technologies, as the orbital angular momentum of LH states makes them more powerful and versatile. To harness these largely unexplored advantages of LH states, we present a new low-dimensional system consisting of highly-strained Ge quantum well (QW) grown on silicon wafers using GeSn as barriers. To quantify the effect of the LH confinement as well as the LH-HH mixing, several spectroscopic techniques were used to identify the LH confined states in the Ge well. The obtained heterostructure shows optical transitions that can be modulated in the midinfrared range. This ability to engineer quantum structure where LH is the ground state in an optically active group IV platform lays the groundwork for a new class of Si-compatible quantum technologies. |
Tuesday, March 3, 2020 9:36AM - 9:48AM |
F65.00009: First-principles theory of highly correlated electronic states in semiconductor spin qubits He Ma, Marco Govoni, Giulia Galli Point defects in wide-gap semiconductors are promising platforms for quantum sensing applications and quantum networks. We present a quantum embedding theory to describe highly correlated electronic states of point defects that are not addressable by conventional density functional theory. We describe the implementation of the method, built on the coupling of the Qbox (www.qboxcode.org/) and WEST (http://www.west-code.org) codes [1], and we demonstrate its accuracy and efficiency for the nitrogen-vacancy center in diamond and several other defects in diamond and SiC. |
Tuesday, March 3, 2020 9:48AM - 10:00AM |
F65.00010: Electrically driven optical interferometry with spins in SiC Kevin Miao, Alexandre Bourassa, Christopher Anderson, Samuel J Whiteley, Alexander Crook, Sam L Bayliss, Gary Wolfowicz, Gergö Thiering, Péter Udvarhelyi, Viktor Ivady, Hiroshi Abe, Takeshi Ohshima, Adam Gali, David Awschalom Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin’s weak coupling to its environment bestows excellent coherence properties [1], but also limits desired drive fields. The excited-state orbitals of these electrons, however, can exhibit stronger coupling to phononic and electric fields [2]. Here, we demonstrate electrically driven coherent quantum interference in the optical transition of single, basally oriented divacancies (VVs) in commercially available 4H silicon carbide [3]. By applying microwave frequency electric fields, we coherently drive the VV's excited-state orbitals and induce Landau-Zener-Stückelberg interference fringes in the resonant optical absorption spectrum. Additionally, we find remarkably coherent optical and spin subsystems enabled by the basal VV's symmetry. These properties establish VVs as strong candidates for quantum communication and hybrid system applications, where simultaneous control over optical and spin degrees of freedom is paramount. |
Tuesday, March 3, 2020 10:00AM - 10:12AM |
F65.00011: Controlling Number of Dopants per Site in Si:P Quantum Devices Jonathan Wyrick, Xiqiao Wang, Ranjit Kashid, Pradeep Namboodiri, Fan Fei, richard Silver STM-based fabrication of atomically precise Si:P structures has been demonstrated as a promising platform for the realization of dopant-based qubit quantum computing. There is a growing broader interest in applying this technique to other quantum systems in Si, for example artificial lattices to engineer band structure, as well as arrays of atoms acting as tunable Hubbard simulators. We present results from a single-atom transistor and few-atom cluster transistors demonstrating the effect that the number of dopants per site has on the energy spectrum of these devices, with the important implication that for many applications of interest it will be necessary to control this parameter with absolute precision. We detail our efforts using STM-based feedback-controlled techniques to engineer placement and number of dopants per site with the goal of reducing the fabrication uncertainty of dopants per site to zero. |
Tuesday, March 3, 2020 10:12AM - 10:24AM |
F65.00012: Tracking interfacial disorder in SiGe qubit material Luis Fabian Pena, Justin C Koepke, Ezra Bussmann Theory predicts quantum dot electrons interact with interface atomic-scale disorder, perturbing energetics, creating new potentially useful states, and adding complexity that could dictate viability of some future qubit technologies. Although profoundly impactful, the predictions are challenging to test, since relevant structures are difficult to measure and correlate with qubit behavior. We've measured atomic step disorder at Si/SiGe interfaces using scanning tunneling microscopy coupled to an epitaxial growth tool. We report a counterintuitive evolution of roughness and step spatial correlations during growth. The results are meaningful toward elucidating structure-function relationships in SiGe QDs. |
Tuesday, March 3, 2020 10:24AM - 10:36AM |
F65.00013: Device development and characterization of Er doped epitaxial Y2O3 on Silicon platform Manish Kumar Singh, Abhinav Prakash, Gary Wolfowicz, Yizhong Huang, Christina Wicker, Alan Dibos, Jianguo Wen, Tijana Rajh, David Awschalom, Tian Zhong, Supratik Guha Spin-optical interface in rare-earth ions enables storage of optical quantum information in the long-lived nuclear spin levels. Er3+ has an optical excitation that matches the telecom transmission wavelength, making it technologically attractive. Further, very narrow transition linewidths and high spectral stability in Er3+ has been demonstrated when embedded in a crystalline host making it an ideal candidate for solid state quantum memory. Using molecular beam epitaxy (MBE), we demonstrate the growth and characterization of high quality single crystal thin films of Er:Y2O3 on Si 111 and Si 100. Photoluminescence (PL) and EPR show substitution of Er at Y sites. PL linewidths of 7.9 GHz and 6 GHz for the 1536 nm transition are obtained at 4 K and 7 mK, respectively. We will discuss the role of the microstructure, buffer layers, isotopic purity (Er 167), and Er3+ proximity to the interfaces on the optical linewidths. Finally, we report the optical transition lifetime, optical and spin coherence lifetimes on the devices fabricated on this platform. Q values for microdisk resonators and loss (db/cm) in optical waveguides will also be presented. |
Tuesday, March 3, 2020 10:36AM - 10:48AM |
F65.00014: Coherent driving of quantum spins via electrically controlled nonlinear magnetization precessions in quantum-classical spin hybrids Avinash Rustagi, Shivam Kajale, Pramey Upadhyaya Coherent drives that are spatially local and at the same time add minimal decoherence when manipulating quantum spins, are of significant interest for quantum technology applications. Spin-spin interactions in quantum impurity spin [like Nitrogen vacancy (NV) center]-nanomagnet hybrids provide a platform where spintronic tools controlling nanomagnet dynamics, can be leveraged to coherently drive the quantum spin. However, decoupling coherent and incoherent dynamics is required for attaining large quality factors. Here, we propose to utilize a novel dynamics regime where electrically controlled nonlinear magnetization precessions of a nanomagnet [Nature materials 11, 39 (2012)] can be used to drive the quantum spin to arbitrary quantum states over the Bloch sphere. We demonstrate that the coherent and incoherent dynamics are decoupled in this regime, thereby showing that such quantum-classical spin hybrids can serve as a coherent drive that is local, electrically-controlled, and decoupled from incoherent dynamics. |
Tuesday, March 3, 2020 10:48AM - 11:00AM |
F65.00015: Strain effects on electronic properties of diamond surfaces Mahesh R Neupane, A. Glen Birdwell, Dmitry A Ruzmetov, Kevin Crawford, Pankaj Shah, James Weil, Tony G. Ivanov Diamond is a wide-bandgap semiconductor with tremendous potential as an electronic device material for power RF applications. In spite of theoretically predicted superior device performance, the high-frequency operation of p-type diamond field-effect transistors (SDFETs) are limited by lower carrier mobilities and charge densities at the surface [2]. These drawbacks are in part due to inter-band scattering of hybridized, degenerate heavy-hole (HH) and light-hole (LH) states near the valance band (VB) edge [3]. Motivated by this, we investigated the effect of biaxial in-plane strain on the electronic properties and carrier dynamics of hydrogenated diamond surfaces (100 and 110) using first principle method. For both the surfaces, a small amount of biaxial tensile strain (< 1%) breaks the degeneracy and lifts the LH band above the HH state and results in the VB band warping. These strain-induced collective phenomena modify VB characteristics and contribute to a reduction in the charge carrier (hole) effective mass leading to an increment in the hole mobility and densities at the surface. 1. Chris J. H. Wort and et al., Materials Today, Vol 11, No. 1-2, 2008. 2. P.B. Shah and et al., MRS Advances, Vol 2, No. 41, 2017. 3. D. Zhang and et al., In. Symp. VLSI Tech. Dig., P 26-27, 2005 |
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