Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session R29: Semiconductor Qubits - Novel Spin Qubit Materials and Technologies IIFocus Live
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Sponsoring Units: DQI Chair: Nico Hendrickx |
Thursday, March 18, 2021 8:00AM - 8:36AM Live |
R29.00001: The germanium quantum information route Invited Speaker: Giordano Scappucci The semiconductor industry knows how to make and integrate billions of excellent transistors. What are the materials requirement that will enable the integration of excellent qubits for the quantum information age of tomorrow? I will make a case for the germanium quantum information route[1] as we are moving into the next phase of engineering qubit systems in the large numbers required for useful quantum computing. Germanium is emerging as a versatile material to realize devices capable of encoding, processing and transmitting quantum information. These devices leverage the special properties of holes in germanium, such as their inherently strong spin--orbit coupling and their ability to host superconducting pairing correlations. I will examine the materials science progress underpinning germanium-based planar heterostructures [2] and review the most significant experimental results demonstrating key building blocks for quantum technology [3,4], identifying the most promising avenues toward scalable quantum information processing in germanium-based systems. |
Thursday, March 18, 2021 8:36AM - 8:48AM Live |
R29.00002: A two-dimensional array of single-hole quantum dots Floor Van Riggelen, Nico Hendrickx, William Lawrie, Maximilian Russ, Amir Sammak, Giordano Scappucci, Menno Veldhorst Quantum dots fabricated using techniques and materials that are compatible with semiconductor manufacturing are promising for quantum information processing. While great progress has been made toward high-fidelity control of quantum dots positioned in a linear arrangement, scalability along two dimensions is a key step toward practical quantum information processing. |
Thursday, March 18, 2021 8:48AM - 9:00AM Live |
R29.00003: Large and tunable g-factor differences in planar-Ge hole singlet-triplet qubits Josip Kukucka, Jaime Saez-Mollejo, Daniel Jirovec, Alessandro Crippa, Andrea Ballabio, Giulio Tavani, Danny Chrastina, Giovanni Isella, Frederico Martins, Georgios Katsaros Hole spins in Ge heterostructures bring together several exceptional properties, which makes them |
Thursday, March 18, 2021 9:00AM - 9:12AM Live |
R29.00004: The Wiggle Well: An oscillatory concentration of germanium within a silicon quantum well Thomas McJunkin, Benjamin Harpt, Yi Feng, Michael Wolfe, Donald E Savage, Max G Lagally, Sue Nan Coppersmith, Mark G Friesen, Robert James Joynt, Mark A Eriksson Motivated by a desire to enhance the splitting between the two low-lying valley states in Si quantum dots for use as qubits, we present a new Si/SiGe heterostructure named the “Wiggle Well”. This heterostructure replaces the pure Si quantum well with an oscillating concentration of Ge (0-9%) in the direction of growth. Theoretical calculations indicate the valley splitting can be increased by matching the oscillation period to one of a set of specific relationships between the reciprocal lattice points and the valley minima wavevector k0. The wavelength presented here is ~1.8 nm. The Wiggle Well is grown via CVD and we present STEM measurements to show the viability of this changing Ge concentration. Hall bar and quantum dot devices are fabricated on this heterostructure. We report an electron transport mobility in the range of 15,000-30,000 cm2/(V s). Valley splitting is measured in two separate quantum dots by excited state spectroscopy and we measure valley splitting in the range 0.1-0.2 meV. Electric field and confinement at the dot are modified while maintaining dot position, and we report a 25% tuning of the single electron valley splitting. We present a discussion of these experimental results in context with our theoretical basis for this heterostructure. |
Thursday, March 18, 2021 9:12AM - 9:24AM Live |
R29.00005: Entanglement of dark electron-nuclear spin defects in diamond Maarten J Degen, Sjoerd Loenen, Hans Bartling, Conor Bradley, Aletta Meinsma, Tim Hugo Taminiau A promising approach for multi-qubit quantum registers is to use optically addressable spins to control “dark” electron-spin defects in their environment. While recent experiments have observed signatures of coherent interactions with such “dark” spins, it is an open challenge to realize the individual control required for quantum information processing. Here we demonstrate the initialization, control and entanglement of individual P1 centers that are part of a spin bath surrounding a nitrogen-vacancy center in diamond. We realize projective measurements to prepare the P1’s multiple degrees of freedom - its Jahn-Teller axis, nuclear spin and charge state - and exploit these to isolate and access multiple P1s in the bath. We develop control and single-shot readout of the nuclear and electron spin, and use this to demonstrate an entangled state of two P1 centers. These results provide a proof-of-principle towards using dark electron-nuclear spin defects as qubit registers for quantum sensing, computation and networks. |
Thursday, March 18, 2021 9:24AM - 9:36AM Live |
R29.00006: Creation and control of spin defects in hexagonal boron nitride Tongcang Li Color centers in diamond and other 3D crystals are excellent candidates for quantum information processing. Recently, there is much exciting progress in color centers in 1D and 2D materials. We have previously demonstrated stable emission and fast optical modulation of quantum emitters in boron nitride nanotubes [Optics Letters, 43, 3778 (2018)]. Recently, we created spin defects in hexagonal boron nitride, a van der Waals material, and observed their electron spin resonance. Thanks to the 2D geometry of hBN, spin defects in hBN will be ideal for studying low-dimensional quantum optomechanics and quantum sensing of other 2D materials. |
Thursday, March 18, 2021 9:36AM - 9:48AM Live |
R29.00007: Towards a quantum register for single 171Yb:YVO ions embedded in a nanophotonic cavity Andrei Ruskuc, Jonathan M Kindem, Joonhee Choi, Chun-Ju Wu, John G Bartholomew, Jake Rochman, Andrei Faraon Optically addressable spins in solid state hosts are a leading candidate for the development of scalable quantum networks. Motivated by the exceptionally long optical and spin coherence times of rare-earth ions, we explore single ytterbium-171 ions coupled to yttrium orthovanadate nanophotonic resonators as a network node architecture. We have demonstrated that these ions have stable optical transitions, 30ms spin coherence times, 99.81% single qubit gate fidelities and 95% single-shot readout fidelities. [1] |
Thursday, March 18, 2021 9:48AM - 10:00AM Live |
R29.00008: Erbium-Implanted Materials for Quantum Communication Paul Stevenson, Christopher Phenicie, Sacha Welinski, Isaiah Gray, Sebastian Horvath, Austin Ferrenti, Robert Cava, Stephen Aplin Lyon, Nathalie De Leon, Jeff Thompson Erbium-doped materials can form spin-photon interfaces wwith optical transitions in the 1.5μm telecom window, making them an exciting class of materials for long-distance quantum communication (QC). Advances in nanophotonic integration have enabled the observation and manipulation of single Er3+ ions, a key result for constructing quantum repeaters. However, these single-ion experiments have also highlighted materials challenges, such as spectral diffusion and magnetic noise-limited spin coherence times. |
Thursday, March 18, 2021 10:00AM - 10:12AM Live |
R29.00009: Towards Coherent Control of the Tin Vacancy in Diamond Romain Debroux, Matthew Trusheim, Dorian A Gangloff, Carola Purser, Noel Wan, Lorenzo De Santis, Luca Huber, Cathryn Michaels, Jesús Arjona Martínez, Ryan Parker, Alexander Stramma, Dirk R. Englund, Mete Atature Spin-photon interfaces in the solid state are highly promising for quantum networks [1]. Towards this end, the ideal system is an optically addressable spin that features long coherence times and can be readily controlled. Here, we report ground-state spin lifetime and magnetic resonance measurements of the tin vacancy (SnV) centre in diamond at cryogenic temperatures. Specifically, we achieve a spin lifetime T1 > 10ms at 3K, limited by phonons in a process that scales exponentially with temperature [2]. We use a direct microwave drive to observe optically detected magnetic resonance and show a spin coherence time T2* = 540ns, limited by fluctuations of the surrounding carbon nuclear spin bath [2]. Finally, we report on progress towards coherent control of the SnV centre spin using an all-optical Raman drive, and towards performing dynamical decoupling of this spin from the nuclear spin bath. These results establish the SnV centre as a competitive candidate for building a quantum network. |
Thursday, March 18, 2021 10:12AM - 10:24AM Live |
R29.00010: Optical control design of single Si-V– and Sn-V– centers in diamond Evangelia Takou, Sophia Economou We design fast, high-fidelity all-optical control of the electron spin qubit of two defects in diamond: the silicon vacancy and the tin vacancy. Our approach can generate arbitrary single qubit rotations through control of the orbital and spin degrees of freedom, both in the absence and presence of an external magnetic field. We test the robustness of our protocols through simulation for various temperatures and use quantum control techniques to mitigate the driving errors and reduce the gate time. |
Thursday, March 18, 2021 10:24AM - 10:36AM Live |
R29.00011: Rydberg excitations of the neutral Silicon Vacancy center in diamond
for ODMR detection Gergô Thiering, Adam Gali Impurities in diamond is of interest due to their broad range of applicability. The negatively charged silicon vacancy defects [SiV(-)] were demonstrated to form indistinguishable single photon sources in diamond with addressable electron spin. However, milikelvin temperatures are required for actual spin manipulation that limits its applicability. Recently, it has been found that the neutral SiV(0) with S=1 system has a long coherence time and is very promising for quantum communication applications1. However, the electronic structure of SiV(0) is not yet completely understood. Based on our recent theory2,3, we employ plane-wave supercell calculations on SiV(0) by means of density functional theory to map the Rydberg-like bound exciton states above the zero phonon optical transition at around 1.41 eV. We show that excitons can localize around SiV(0) that provides 1s, 2s, 2p… Rydberg series. Illumination to these states results in the ODMR detection of SiV(0) spin. |
Thursday, March 18, 2021 10:36AM - 10:48AM Live |
R29.00012: Group IV color centers in single crystal diamond membrane for quantum network Xinghan Guo, Zixi Li, Tianle Liu, Nazar Delegan, Yu Jin, David Awschalom, Giulia Galli, F. Joseph, Alexander A High Group IV color centers in single crystal diamond have emerged as promising candidates for realizing long-range quantum optical network, thanks to their coherent optical transitions and controllable spin states. To fully utilize their superb optical and spin properties, it is critical to integrate them with other on-chip optical and electrical structures. Using single crystal diamond membrane, we developed a versatile platform that enables strain tuning and nanophotonic integration. As a result, individual quantum emitters such as silicon vacancy (SiV) and germanium vacancy (GeV) centers, have shown stable optical emissions with high contrasts and narrow linewidths (200-500 MHz). Recent progress related to strain engineering of these color centers will also be discussed. |
Thursday, March 18, 2021 10:48AM - 11:00AM Live |
R29.00013: Optically addressable molecular spin qubits Sam L Bayliss, Daniel W Laorenza, Peter J Mintun, Berk Diler Kovos, Danna Freedman, David Awschalom Solid-state color centers are a promising platform for quantum technologies due to their combination of a ground-state spin which can be initialized and read out optically. However, their top-down architecture makes it challenging to atomistically control their properties. Chemically synthesized molecules provide an alternative bottom-up approach for optically addressable spin systems, offering an intrinsically tunable, scalable and host-agnostic architecture. |
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