A5018885489- Quantum and electron transport phenomena
- Quantum Information and Cryptography
- Semiconductor Quantum Structures and Devices
- Quantum Computing Algorithms and Architecture
- Quantum optics and atomic interactions
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Quantum-Dot Cellular Automata
- Photonic and Optical Devices
- Diamond and Carbon-based Materials Research
- Solid-state spectroscopy and crystallography
- Neural Networks and Reservoir Computing
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Magneto-Optical Properties and Applications
- Photonic Crystals and Applications
- Magnetic and transport properties of perovskites and related materials
- Force Microscopy Techniques and Applications
- Thin-Film Transistor Technologies
- Electron Spin Resonance Studies
- Mechanical and Optical Resonators
- Magnetic Field Sensors Techniques
- Crystallography and Radiation Phenomena
HRL Laboratories (United States)
2016-2025
University of Konstanz
2023
UNSW Sydney
2020-2021
Princeton University
2020
Stanford University
2004-2013
Palo Alto University
2005-2013
National Institute of Informatics
2007-2012
University of California, Berkeley
2010
Simon Fraser University
2010
InfoConsult (Germany)
2010
The spin degree of freedom an electron or a nucleus is one the most basic properties nature and functions as excellent qubit, it provides natural two-level system that insensitive to electric fields, leading long quantum coherence times. We review physics semiconductor qubits, focusing not only on early achievements initialization, control, readout in GaAs dots, but also recent advances Si Ge including improved charge control readout, coupling other degrees freedom, scaling larger sizes....
We develop a layered quantum computer architecture, which is systematic framework for tackling the individual challenges of developing while constructing cohesive device design. discuss many prominent techniques implementing circuit-model computing and introduce several new methods, with an emphasis on employing surface code error correction. In doing so, we propose architecture based optical control dots. The timescales physical hardware operations logical, error-corrected gates differ by...
We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity exchange operations to charge noise. The method involves biasing a double dot symmetrically between charge-state anticrossings, where derivative energy with respect gate voltages is minimized. Exchange remains highly tunable adjusting tunnel coupling. find that this reduces dephasing effect noise more than factor 5 in comparison near anticrossing, increasing number...
Like modern microprocessors today, future processors of quantum information may be implemented using all-electrical control silicon-based devices. A semiconductor spin qubit controlled without the use magnetic fields by three electrons in tunnel-coupled dots. Triple dots have previously been GaAs, but this material suffers from intrinsic nuclear noise. Reduction noise is possible fabricating devices isotopically purified silicon. We demonstrate universal coherent a triple-quantum-dot an...
Qubits encoded in a decoherence-free subsystem and realized exchange-coupled silicon quantum dots are promising candidates for fault-tolerant computing. Benefits of this approach include excellent coherence, low control crosstalk, configurable insensitivity to certain error sources. Key difficulties that entangling gates require large number pulses high-yielding dot arrays. Here we show device made using the single-layer etch-defined gate electrode architecture achieves both required...
We describe a quantum repeater protocol for long-distance communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using weak dispersive light-matter interaction and distributing outgoing bright coherent-light pulses among stations. Noisy entangled pairs electronic spin are then prepared with high success probability via homodyne detection postselection. The local gates purification swapping deterministic measurement-free, based upon...
A solid-state implementation of a quantum computer composed entirely silicon is proposed. Qubits are 29Si nuclear spins arranged as chains in 28Si (spin-0) matrix with Larmor frequencies separated by large magnetic field gradient. No impurity dopants or electrical contacts needed. Initialization accomplished optical pumping, algorithmic cooling, and pseudo-pure state techniques. Magnetic resonance force microscopy used for ensemble measurement.
We describe a system for long-distance distribution of quantum entanglement, in which coherent light with large average photon number interacts dispersively single, far-detuned atoms or semiconductor impurities optical cavities. Entanglement is heralded by homodyne detection using second bright pulse phase reference. The use pulses leads to high success probability the generation at cost lower initial fidelity. This fidelity may be boosted entanglement purification techniques, implemented...
Quantum communication typically involves a linear chain of repeater stations, each capable reliable local quantum computation and connected to their nearest neighbors by unreliable links. The rate existing protocols is low as two-way classical used. By using surface code across the generating Bell pairs between neighboring stations with probability heralded success greater than 0.65 fidelity 0.96, we show that can be avoided information sent over arbitrary distances arbitrarily error at...
We present a new control algorithm and system design for network of quantum repeaters, outline the end-to-end protocol architecture. Such will create long-distance states, supporting key distribution as well distributed computation. Quantum repeaters improve reduction quantum-communication throughput with distance from exponential to polynomial. Because state cannot be copied, repeater is not signal amplifier, but rather executes algorithms teleportation in conjunction specialized type error...
Silicon quantum dot spin qubits provide a promising platform for large-scale computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using $^{28}$Si enriched material. A scalable error-corrected processor, however, will require control many in parallel, while performing error detection across constituent qubits. Spin resonance techniques are convenient path to parallel two-axis control, Pauli blockade can be used realize local...
We demonstrate rapid high-fidelity state preparation and measurement in exchange-only Si/SiGe triple-quantum-dot qubits. Fast integration (980-ns) initialization (approximately 300-ns) operations are performed with all-electrical baseband control. emphasize a leakage-sensitive joint metric, developed the context of qubits but applicable more broadly, report an infidelity 2.5±0.5×10−3. This result is enabled by high-valley-splitting heterostructure, at two- to three-electron charge boundary,...
We report NMR experiments using high-power rf decoupling techniques to show that a $^{29}\mathrm{Si}$ nuclear spin in solid silicon crystal at room temperature can preserve quantum phase for ${10}^{9}$ precessional periods. The coherence times we are more than four orders of magnitude longer any other observed solid-state qubit. also examine magic-angle-spinning and isotopically altered samples. In high-quality crystals, limited by residual dipolar couplings be further improved isotopic...
In a large-scale quantum computer, the cost of communications will dominate performance and resource requirements, place many severe demands on technology, constrain architecture. Unfortunately, fault-tolerant computers based entirely photons with probabilistic gates, though equipped "built-in" communication, have very large overheads; likewise, reliable gates between or memories may lack sufficient communication resources in presence realistic optical losses. Here, we consider compromise...
We demonstrate quantum interference between photons generated by the radiative decay processes of excitons that are bound to isolated fluorine donor impurities in $\mathrm{ZnSe}/\mathrm{ZnMgSe}$ quantum-well nanostructures. The ability generate single from these devices is confirmed autocorrelation experiments, and indistinguishability emitted two independent nanostructures via a Hong-Ou-Mandel dip. These results indicate appropriately engineered semiconductor structures can portray atomlike...
We analyze how the performance of a quantum-repeater network depends on protocol employed to distribute entanglement, and we find that choice repeater-to-repeater link has profound impact communication rate as function hardware parameters. develop numerical simulations quantum networks using different protocols, where repeater is modeled in terms key parameters, such photon generation collection efficiency. These parameters are motivated by recent experimental demonstrations dots, trapped...
We design and analyze a logical qubit composed of linear array electron spins in semiconductor quantum dots. To avoid the difficulty fully controlling two-dimensional dots, we adapt spin control error correction to one-dimensional line silicon Control speed efficiency are maintained via scheme which states controlled globally using broadband microwave pulses for magnetic resonance while two-qubit gates provided by local electrical exchange interaction between neighboring Error with two-,...