Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T74: Semiconducting Qubits IIIFocus
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Sponsoring Units: DQI Chair: Matias Urdampilleta, CNRS Institut Néel Room: Room 403/404 |
Thursday, March 9, 2023 11:30AM - 12:06PM |
T74.00001: Hole spin qubit in silicon: enhanced coherence and coherent coupling to microwave photons Invited Speaker: Romain Maurand Semiconductor spin qubits based on spin-orbit states stand as promising candidates for quantum information processing. In particular, owing to the spin-orbit interaction (SOI) of valence band states, hole spins are responsive to electric field excitations, allowing for practical and fast qubit control. This spin-electric response is intimately link to the rich spin-orbit physics [1,2]. Here we will report on our last efforts leveraging spin-orbit interaction of hole spin in silicon devices produced on a semi-industrial 300mm CMOS foundry [3]. First, we will demonstrate how SOI turns into an asset to engineer mixed spin-charge states in a double quantum dot able to couple strongly with microwave photons. In an hybrid spin cQED platform, we find a hole spin-photon coupling of 300 MHz associated to a cooperativity above 103 [4]. Secondly, due to their spin-electric susceptibility, spin-orbit qubits may be vulnerable to electrical noise explaining the relatively short coherence time reported so far. Here we will report on the existence of preferential magnetic field orientation at which a spin-orbit qubit is decoupled from charge noise while keeping its efficient electrical control [5]. In this peculiar operation regime, we measure an enhanced Hahn-Echo decay time in the order of 100 microseconds maintaining Rabi frequencies in the MHz range [6]. All together, the coupling to microwave photon and the ability to hide from charge noise make hole spin in silicon an attractive platform to further develop semiconductor spin qubit-based quantum information processing. |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T74.00002: Electronic Transport in Atomically Precise Semiconductor Tunnel Junctions Matthew B Donnelly, Mushita M Munia, Joris G Keizer, Yousun Chung, A M Saffat-Ee Huq, Edyta Osika, Yuling Hsueh, Rajib Rahman, Michelle Y Simmons Electron tunnelling is of fundamental importance in the design and operation of semiconductor nanostructures such as field effect transistors (FETs) and quantum computing devices. The exponential sensitivity of tunnelling requires precision fabrication techniques to engineer the desired tunnelling resistances/tunnel rates for high fidelity spin readout and qubit exchange. To compliment these fabrication techniques, accurate modelling at the atomic scale is useful for predictive device design, becoming more complex when devices have arbitrary shapes/geometries. In this work we combine atomic precision patterning using STM lithography with tight-binding Non-equilibrium Green's Functions (TB-NEGF) modelling to describe the dependence of tunnelling on junction length in monolayer degenerately phosphorus doped silicon tunnel junctions. We find near perfect agreement between experiment and modelling with our model allowing us to accurately determine the barrier height (57.5 meV ± 1 meV) and lateral seam width (0.39 nm ± 0.01 nm) of these nanoscale junctions. Our work suggests that further applications of the TB-NEGF formalism to semiconductor nanostructures will provide detailed knowledge of devices electrostatics and tunnelling properties, enabling improved device performance at the nanoscale. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T74.00003: Machine assisted classification of multi-donor clusters using scanning tunnelling microscopy Sam Sutherland Donor atom qubits in silicon, fabricated via scanning tunnelling microscope (STM) lithography, are a promising platform for realizing full-scale quantum computing architectures. Since the properties of each qubit depend on their exact atomic make-up, automated fabrication routines have been developed to monitor and control the number of donor atoms at each qubit site when scaling up to larger qubit arrays. Herein, a strategy is demonstrated which allows, for the first time, accurate and real-time prediction of the donor number at each qubit site during the STM fabrication of donor devices in silicon. In this method, machine learning techniques for image recognition are used to determine the probability distribution of donor numbers from the STM image of the qubit site. Models in excess of 90% accuracy are consistently obtained by mitigating overfitting through reduced model complexity, image preprocessing, data augmentation, and examination of the intermediate layers of the convolutional neural networks. The results presented in this paper provide a unique means to understand the chemical dissociation pathways for hydrogen lithography and constitute an important milestone in automating the fabrication of quantum devices for computation and sensing applications. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T74.00004: Magnetotransport in the quantum wires comprised of vertically stacked quantum dots: A calling for themagnetoplasmon qubits Manvir S Kushwaha We report on a periodic system of vertically stacked InAs/GaAs quantum dots (VSQD) subjected |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T74.00005: Analog Quantum Simulation of the Dynamics of Open Quantum Systems with Quantum Dots and Microelectronic Circuits Ignacio Franco, John Nichol, Andrew N Jordan, Chang Woo Kim We introduce a general setup for the analog quantum simulation of the dynamics of open quantum systems based on semiconductor quantum dots electrically connected to a chain of quantum RLC electronic circuits. The dots are chosen to be in the regime of spin-charge hybridization to enhance their sensitivity to the RLC circuits while mitigating the detrimental effects of unwanted noise. In this context, we establish an experimentally realizable map between the hybrid system and a qubit coupled to thermal harmonic environments of arbitrary complexity that enables the analog quantum simulation of open quantum systems. We assess the utility of the simulator by numerically exact emulations that indicate that the experimental setup can faithfully mimic the intended target even in the presence of its natural inherent noise. We further provide a detailed analysis of the physical requirements on the quantum dots and the RLC circuits needed to experimentally realize this proposal that indicates that the simulator can be created with existing technology. The approach can exactly capture the effects of highly structured non-Markovian quantum environments typical of photosynthesis and chemical dynamics, and offer clear potential advantages over conventional and even quantum computation. The proposal opens a general path for effective quantum dynamics simulations based on semiconductor quantum dots. |
Thursday, March 9, 2023 12:54PM - 1:06PM |
T74.00006: Jellybean quantum dots in silicon for qubit coupling Arne Laucht, Zeheng Wang, Santiago Serrano, MengKe Feng, William Gilbert, Ross Leon, Tuomo I Tanttu, Philip Mai, Dylan Liang, Jonathan Y Huang, Yue Su, Wee Han Lim, Fay E Hudson, Christopher Escott, Andrea Morello, Chih-Hwan Yang, Andrew S Dzurak, Andre Saraiva The small size and excellent integrability of silicon metal-oxide-semiconductor (SiMOS) quantum dot spin qubits make them an attractive system for mass-manufacturable, scaled-up quantum processors. Furthermore, classical control electronics can be integrated on-chip, in-between the qubits, if an architecture with sparse arrays of qubits is chosen. In such an architecture qubits are either transported across the chip via shuttling, or coupled via mediating quantum systems over short-to-intermediate distances. In this presentation, we will report on the charge and spin characteristics of an elongated quantum dot – a so-called jellybean quantum dot – for the prospects of acting as a qubit-qubit coupler. Charge transport, charge sensing and magneto-spectroscopy measurements are performed on a SiMOS quantum dot device at mK temperature, and compared to Hartree-Fock multielectron simulations. At low electron occupancies where disorder effects and strong electron-electron interaction dominate over the electrostatic confinement potential, the data reveals the formation of three coupled dots, akin to a tunable, artificial molecule. One dot is formed centrally under the gate and two are formed at the edges. At high electron occupancies, these dots merge into one large dot with well-defined spin states, verifying that jellybean dots have the potential to be used as qubit couplers in future quantum computing architectures. |
Thursday, March 9, 2023 1:06PM - 1:18PM |
T74.00007: Si/SiGe Qubit Devices Enabled by Advanced Semiconductor Fabrication Eric Henry Intel’s Components Research and Intel Labs organizations have recently demonstrated the industry’s highest reported yield (95%) and uniformity to date of silicon spin qubit devices. These devices are fabricated on a planar Si/SiGe heterostructure with extreme ultraviolet (EUV) lithography utilizing Intel’s advanced 300mm transistor research and development facility. This achievement represents a major milestone for quantum chip fabrication and scaling on Intel’s transistor manufacturing processes line. An overview of the process integration scheme, process parameters and low temperature device characterization that led to these innovative advancements toward technology maturation and commercialization will be discussed. |
Thursday, March 9, 2023 1:18PM - 1:30PM |
T74.00008: Reduced plasma oxidation in metal single electron transistors for increased bandwidth Runze Li, Pradeep N Namboodiri, Yanxue Hong, Dmitri Krymski, Joshua Pomeroy Plasma oxidation parameters used to form the tunnel barriers in aluminum based single electron transistors (SETs) are varied to reduce the resistance-area (RA) product, thereby increasing the conductance and bandwidth for use as quantum dot charge sensors. Aluminum based SETs with high bandwidth could be integrated into the MOS gate layer for spin qubit readout and reduce pressure on in-plane densities. Our group’s previous work applied plasma oxidation to yield SETs sufficiently stable over weeks, allowing the metal-based SET to be considered for qubit readout. By varying the plasma oxidation duration, the resistance of the tunnel junction can be tuned, which both increases electrical conductance and bandwidth. Coulomb blockade measurements taken on these plasma oxidized SETs will be presented and analyzed for their potential as charge sensors in this context. |
Thursday, March 9, 2023 1:30PM - 1:42PM |
T74.00009: Characterizing Charged Defects in Oxide-on-Silicon using Kelvin Probe Force Microscopy Leah Tom, Zachary J Krebs, Emily S Joseph, Keith G Ray, Vincenzo Lordi, Mark A Eriksson, Victor Brar, Susan N Coppersmith, Mark Friesen While silicon-based quantum dot qubits are a promising platform for quantum computing, charge noise from oxide layers below and in between the gate electrodes hinders critical improvements in qubit operations. To characterize the microscopic origin of charge noise in the gate oxide, we perform Kelvin Probe Force Microscopy (KPFM) measurements on an aluminum oxide layer grown by ALD atop bulk silicon. These experiments reveal defects in the oxide that exchange charges with the AFM tip when the tip-backgate bias voltage is swept. We repeat such scans while rastering the tip over the sample and varying the tip-sample separation. By comparing measurements with electrostatic simulations of the tip and sample system, we are able to use the measured charging voltages to extract defect energies relative to aluminum oxide’s valence band. These results will be useful for understanding a major source of charge noise in our devices and potentially improving qubit gate operations. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T74.00010: Reducing Tuning Complexity in Top Gated Semiconductor Quantum Dot Qubits with single-nm-resolution Gate Fabrication James H Owen, Felix Beaudoin, John N Randall Top gated semiconductor quantum dot qubits represent an attractive path to quantum computing. However, variations in the physical dimensions of the top gates create significant variations in the size of the electrostatic confinement and therefore the energy levels in the qubit. The variation in gate dimensions complicates the design of multi qubit systems and the required tuning of the biases on the gates for multiple qubits is so complex that machine learning is employed. |
Thursday, March 9, 2023 1:54PM - 2:06PM |
T74.00011: Quantum simulating floating phase and S = ½ critical behavior with S = 1 spin centers with anisotropy in solid-state materials Troy Losey, Denis R Candido, Yannick L Meurice, Michael E Flatté, Shan-Wen Tsai, Jin Zhang We propose a novel platform for creating quantum simulators by implanting S = 1 spin centers in solid-state materials. We show that with anisotropy and Zeeman splitting, a 1-d chain of S = 1 spin centers that interact through the magnetic dipole-dipole interaction can be mapped to a S = ½ XYZ + H Heisenberg spin chain. This Hamiltonian can then be tuned by changing the orientation of the chain with respect to the symmetry axes of the spin centers and by varying a small external magnetic field. The phase diagram for this system is rich with critical behavior and shows regions with a critical floating phase, an isotropic Heisenberg model, and a transverse Ising universality class. This system can be used to quantum simulate critical behavior seen in unique S = ½ XYZ + H spin chains and is the first quantum simulator for the floating phase with spin centers in solid-state materials. |
Thursday, March 9, 2023 2:06PM - 2:18PM |
T74.00012: Global coherent spin control of a SiMOS spin qubit using a 3D KTaO3 dielectric resonator Nard Dumoulin Stuyck, Ensar Vahapoglu, James Slack-Smith, Wee Han Lim, Fay E Hudson, Tom Day, Tuomo I Tanttu, Henry Yang, Andre Saraiva, Kohei M Itoh, Arne Laucht, Andrew S Dzurak, Jarryd J Pla As spin qubit numbers are growing, novel scalable control mechanisms become crucial for large-scale qubit architectures. One promising approach to deliver homogeneous oscillating magnetic field over macroscopic length-scales is the use of 3D dielectric resonators. KTaO3 resonators have high permittivity at cryogenic temperatures, and have demonstrated fast and coherent control of spins in NV ensembles and single spin control in SiMOS quantum dots [1-3]. In this latter demonstration, charge noise originating from the Pd/ALD AlOx gate stack limited spin coherence, while electric coupling to metallic gate structures introduced unwanted microwave current loops impacting resonator quality factor and achievable driving speeds. Here, we will present our latest results on KTaO3 global spin control using a modified SiMOS spin qubit design with an optimised Al/thermally grown AlOx gate stack. Removing current loops identified by finite element simulations from the design, the measured resonator quality factor of 1200 improved by 50% compared to our previous generation device. Next to the latest results on global spin control, limiting factors of the resonator-device design will be discussed. This work highlights the promise of dielectric resonators for global spin control in large-scale spin qubit arrays. |
Thursday, March 9, 2023 2:18PM - 2:30PM |
T74.00013: Quantum simulations of the Su–Schrieffer–Heeger model in P-doped silicon devices Maicol A Ochoa, Keyi Liu, Piotr Rózanski, Michal Zielinski, Garnett W Bryant The atomic precision of impurity placement in dopant-based silicon devices makes them ideal for use in analog quantum simulation. Recently, the Simmons group reported analog simulations of the Su-Schrieffer-Heeger (SSH) model (Nature 606, p.694 (2022)) in an array of silicon quantum dots, each consisting of about 25 P atoms, demonstrating trivial and topological phases. Here, we explore the possibility of realizing an SSH system in zig-zag arrays of single P-atom quantum dots in Si. We implement atomistic tight-binding, configuration-interaction calculations for systems with 6 to 10 phosphorus atoms and modulate the electron hopping and intersite Coulomb interactions by varying the staggered distribution and separation of the impurities. Our fully atomistic calculations for trivial and topological arrays reveal the differences in the single and many-particle states that arise due to geometry, valley splitting, and interaction. In particular, we resolve from the energy spectrum and charge distribution effects of valley splitting, that go beyond the SSH model, and characterize the formation of the topological phases and edge states at half-filling as a function of P-P distance. |
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