Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Z39: Spin Qubit Arrays IIFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DQI DCMP Chair: Anthony Sigillito, UPenn Room: McCormick Place W-196A |
Friday, March 18, 2022 11:30AM - 12:06PM |
Z39.00001: Charge and spin coherent control in semiconductor quantum dot arrays Invited Speaker: Tristan Meunier Controlling electron spins coherently in larger and larger quantum dot arrays is a prerequisite for the development of electron spin-based quantum processors. We will review our effort to control the charge and spin degrees of freedom of individual electrons in 2D arrays up to 9 tunnel-coupled semiconductor quantum dots. Procedures for deterministic filling, spin initialization, spin readout, spin manipulation and spin transfer and consideration for spin dynamics in the array will be discussed. |
Friday, March 18, 2022 12:06PM - 12:18PM |
Z39.00002: Floquet-enhanced spin swaps Haifeng Qiao The transfer of information between quantum systems is essential for quantum communication and computation. In quantum computers, high connectivity between qubits can improve the efficiency of algorithms, assist in error correction, and enable high-fidelity readout. However, as with all quantum gates, operations to transfer information between qubits can suffer from errors associated with spurious interactions and disorder between qubits, among other things. Here, we harness interactions and disorder between qubits to improve a swap operation for spin eigenstates in semiconductor gate-defined quantum-dot spins. We use a system of four electron spins, which we configure as two exchange-coupled singlet–triplet qubits. Our approach, which relies on the physics underlying discrete time crystals, enhances the quality factor of spin-eigenstate swaps by up to an order of magnitude. Our results show how interactions and disorder in multi-qubit systems can stabilize non-trivial quantum operations and suggest potential uses for non-equilibrium quantum phenomena, like time crystals, in quantum information processing applications. Our results also confirm the long-predicted emergence of effective Ising interactions between exchange-coupled singlet–triplet qubits. |
Friday, March 18, 2022 12:18PM - 12:30PM |
Z39.00003: Coherent multiqubit control in a six quantum dot linear array in Si/SiGe Mateusz T Madzik, Stephan G Philips, Maximilian Russ, Sergey V Amitonov, Sander L de Snoo, Delphine Brousse, Larysa Tryputen, Brian Paquelet Wuetz, Amir Sammak, Giordano Scappucci, Lieven Vandersypen Quantum dots are actively researched for applications in quantum computing, and show a large potential for scalability thanks to their small size. In particular, silicon quantum dots continue to stand out as a promising platform, with high fidelity single-qubit gates and two-qubits gates, qubit operation at temperatures exceeding 1 Kelvin and possible industrial CMOS integration. Scaling up to larger qubit numbers remains today's main challenge. Here we demonstrate universal quantum control of six spin qubits. Our experiments are conducted on a linear array of electrostatically defined quantum dots confined in the 28Si quantum well of a 28Si/SiGe heterostructure. Qubit initialization is based on measurement of the spin state across the array followed by real-time feedback to place all qubits in the target initial state. No access to electron reservoirs is needed to bring in fresh electrons. Site-selective addressing is achieved by EDSR in a magnetic field gradient that separates the qubit frequencies from each other. Two-qubit gates are activated selectively by lowering the tunnel barrier between a pair of neighboring dots. We quantify multiqubit entanglement through quantum state tomography for 2 and 3 qubits and by calculating entanglement witnesses for GHZ states. |
Friday, March 18, 2022 12:30PM - 12:42PM |
Z39.00004: Quantum Computation Protocol for Dressed Spins in a Global Field Amanda E Seedhouse, Andre Saraiva, Ingvild Hansen, Andrew S Dzurak, Arne Laucht, Henry Yang Spin qubits are contenders for scalable quantum computation because of their long coherence times demonstrated in a variety of materials, but individual control by frequency-selective addressing using pulsed spin resonance creates challenges for scaling up to many qubits. This individual resonance control strategy requires each spin to have a distinguishable frequency, imposing a maximum number of spins that can be individually driven before qubit crosstalk becomes unavoidable. Here we describe a complete strategy for controlling a large array of spins in quantum dots dressed by an on-resonance global field, namely a field that is constantly driving the spin qubits, to dynamically decouple from the effects of background magnetic field fluctuations. This approach - previously implemented for the control of single electron spins bound to electrons in impurities - is here harmonized with all other operations necessary for universal quantum computing with spins in quantum dots. We define the logical states as the dressed qubit states and discuss initialization and readout utilizing Pauli spin blockade, as well as single- and two-qubit control in the new basis. Finally, we critically analyze the limitations imposed by qubit variability and potential strategies to improve performance. |
Friday, March 18, 2022 12:42PM - 12:54PM |
Z39.00005: Characterization of Silicon MOS quantum dots fabricated in a full 300mm CMOS process for spin qubit applications Asser Elsayed, Ruoyu Li, Clement Godfrin, Nard Dumoulin Stuyck, Stefan Kubicek, Julien Jussot, Yann Canvel, Shana Massar, Fahd A. Mohiyaddin, Mohamed K Shehata, George Simion, Pol Van Dorpe, Iuliana Radu, Bogdan Govoreanu Silicon spin qubits have been considered as one of the most promising candidates for large scale quantum computers, due to their long coherence time, potential to operate at relatively high temperatures and compatibility with CMOS technology for upscaling [1-2]. However, experimental demonstrations have been limited to a few qubits [3-4], and further upscaling requires better process control and a thorough characterization of material properties. |
Friday, March 18, 2022 12:54PM - 1:06PM |
Z39.00006: The SMART protocol for scalable quantum computing Ingvild Hansen, Amanda E Seedhouse, Chih-Hwan Yang, Andre Saraiva, Arne Laucht, Kok Wai Chan, Fay E Hudson, Kohei M Itoh, Andrew S Dzurak Global control strategies for arrays of qubits are a promising pathway to scalable quantum computing. A continuous-wave global field provides decoupling of the qubits from background noise. However, this approach is limited by variability in the parameters of individual qubits in the array. Here we show that by modulating a global field simultaneously applied to the entire array, we are able to encode qubits that are less sensitive to the statistical scatter in qubit resonance frequency and microwave amplitude fluctuations. We name this approach the SMART (Sinusoidally Modulated, Always Rotating and Tailored) qubit protocol. We also report the experimental implementation of the SMART protocol in a single spin confined in a SiMOS quantum dot and confirm the optimal modulation conditions predicted from theory. Universal control of a single qubit is demonstrated using modulated Stark shift control via the local gate electrodes. We measure an extended coherence time of 2 ms and an average Clifford gate fidelity > 99%, constituting a significant improvement over a conventional spin qubit. This work shows that future scalable spin qubit arrays could be operated using global microwave control and local gate addressability, while maintaining robustness to experimental inhomogeneities. |
Friday, March 18, 2022 1:06PM - 1:18PM |
Z39.00007: Conveyor-mode single-electron shuttling in Si/SiGe for a scalable quantum computing architecture Inga Seidler, Tom Struck, Ran Xue, Niels Focke, Stefan Trellenkamp, Hendrik Bluhm, Lars R Schreiber Small spin-qubit registers defined by single electrons confined in Si/SiGe quantum dots operate successfully and connecting these could permit scalable quantum computation. Shuttling the qubit between registers is a natural choice for high-fidelity coherent links [1]. Electron shuttling by Landau-Zener transitions across a series of tunnel-coupled quantum dots was shown [2], but required invidually tuned voltages. |
Friday, March 18, 2022 1:18PM - 1:30PM |
Z39.00008: FIB-based Single Ion Implantation with >99% Detection Confidence – Towards Near-Surface Donor Qubit Architectures in Silicon Simon G Robson, Paul Räcke, Alexander M Jakob, Nicholas Collins, Hannes R Firgau, Vivien Schmitt, Vincent Mourik, Andrea Morello, Daniel Spemann, David N Jamieson Silicon chips incorporating large-scale donor-qubit arrays show great potential for spin-based quantum computation. Single ion implantation into an active detection substrate is a promising fabrication technique when combined with a method to accurately localise the ion implant site. Here, we introduce a new approach to enhance the device development process and enable the construction of near-surface donor-qubit arrays with high yield. Using a modified focussed ion beam system equipped with an electron beam ion source and ultra-low noise on-chip ion detection electronics (~70 eV r.m.s), we demonstrate a powerful method to evaluate the device’s spatial response to single ion impacts. A sub-500 nm beam spot together with a range of species and acceleration energies down to a few keV allow detailed maps of the device's underlying electrical landscape to be acquired. These aid in understanding the role interface and bulk defects play in the ion detection response, and provide further insight to the physics of ion-solid interactions. Furthermore, we show the ability to perform 2000 counted 24 keV Ar2+ implants into a 25μm2 area with 99.99% detection fidelity, demonstrating an attractive framework for future rapid mask-free engineering of scalable shallow donor-qubit nanoarrays. |
Friday, March 18, 2022 1:30PM - 1:42PM |
Z39.00009: Engineering topological states in atom-based semiconductor quantum dots Mitchell Kiczynski, Samuel K Gorman, Helen Geng, Matthew B Donnelly, Yousun Chung, Yu He, Joris G Keizer, Michelle Y Simmons Analogue quantum simulators have long promised the ability to simulate emergent microscopic phenomena in physics beyond the capability of classical computers. Recent results in semiconductor quantum dots have demonstrated simulation of the Fermi-Hubbard model and Nagaoka ferromagnetism, the simplest one-dimensional model of strongly correlated topological insulators, the many body Su-Schrieffer-Heeger (SSH) model has remained elusive. Realising strong quantum correlations in interacting Fermionic systems is difficult due to the challenge of precisely engineering long-range interactions between electrons such that the system is not destroyed. Here, we show that for precision placed atoms in silicon with strong Coulomb confinement we can engineer a minimum of 6 all-epitaxial in-plane gates to tune the electrochemical potential across the chain to realise both the trivial and topological phases of the many-body SSH model in a linear array of 10 quantum dots. The strong on-site energies (U ~ 30 meV) and unique staggered device design allow us to tune the ratio between inter- and intracell electron transport to observe clear signatures of a topological phase with 2 conductance peaks at quarter-filling compared to the 10 conductance peaks of the trivial phase. The demonstration of the SSH model in a Fermionic system designed with sub-nanometre precision and low-gate densities, isomorphic to qubits, has identified a highly controllable quantum system that can be used for future simulations of strongly interacting electrons. |
Friday, March 18, 2022 1:42PM - 1:54PM |
Z39.00010: On-demand electrical control of spin qubits Will Gilbert, Tuomo I Tanttu, Wee Han Lim, MengKe Feng, Jonathan Huang, Jesus D Cifuentes Pardo, Santiago Serrano, Philip Mai, Ross Leon, Christopher Escott, Kohei M Itoh, Michael Thewalt, Fay E Hudson, Arne Laucht, Chih-Hwan Yang, Andre Saraiva, Andrew S Dzurak Once called a “classically non-describable two-valuedness” by Pauli, the electron spin is a natural stage for long-lived quantum information since it is mostly impervious to electric noise. This immunity comes at the price of limiting the options for implementing gate operations in spin-based quantum computation – paradoxically, the most scalable control strategy is the exploitation of relativistic spin-orbit effects to couple spins back to electric fields. We have developed a technique to create switchable interaction between spins and orbital motion of electrons in silicon quantum dots. The naturally weak effects of spin-orbit interaction in silicon are enhanced by more than three orders of magnitude by controlling the energy quantisation of the electron in the nanostructure, enhancing the orbital motion within the quantum dot. The enhanced electrical control is demonstrated in multiple devices and electronic configurations, endorsing the applicability of this technique for large arrays of qubits. We are able to achieve decoherence times of T2,Hahn ≈ 50 μs, single qubit π/2-gates as fast as Tπ/2 = 3 ns and gate fidelities of 99% probed by randomised benchmarking. Solving this dilemma in Silicon creates a strong perspective for scalability of quantum processors. |
Friday, March 18, 2022 1:54PM - 2:06PM |
Z39.00011: Uniform and tuneable 'all-silicon' spin qubit devices in a 300mm integrated process Nard Dumoulin Stuyck, Roy Li, Clement Godfrin, Asser Elsayed, Fahd Mohiyaddin, Stefan Kubicek, Julien Jussot, Yann Canvel, Shana Massar, George Simion, Marc Heyns, Iuliana Radu, Bogdan Govoreanu Semiconductor spin qubits are developing at a rapid pace with increasing qubit coherence times and quantum gate-fidelities over the last years [1-2]. This progress has resulted in multiple proposals for large-scale spin qubit-arrays [3-4]. However, scaling up existing qubit prototypes to several qubit arrays require highly uniform spin qubit devices. |
Friday, March 18, 2022 2:06PM - 2:18PM |
Z39.00012: Quantum characterization of 6-dot exchange-only qubit arrays in the SLEDGE architecture Robert K Lanza, Nathan S Holman We discuss coherent characterization of multiple 6-dot qubit array devices based on the Single-Layer Etch-Defined Gate-Electrode (SLEDGE) architecture [1] implemented in isotopically enhanced Si/SiGe. Each 6-dot array comprises two exchange-only qubits encoded in triple-dot decoherence-free subsystems (DFS). These array-wide characterizations are enabled by yield enhancements offered by SLEDGE and include the singlet-triplet pairwise dephasing times (T2*), dominated by 73Ge [2]; Q-factors reflective of charge noise magnitude for all 5 adjacent exchange axes [3]; calibration of voltage throw to exchange rotation angle for all exchange axes [4]; and excited-state energy splittings using differential axis pulsed spectroscopy (DAPS) [5]. We use the resulting key device parameters to inform error models for predicting the fidelity of exchange-only gate operations and compare those to experimental single-qubit randomized benchmarking. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700