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van Riggelen, F. (author)In this thesis, research is presented that explores the characteristics and possibilities of hole spin qubits defined in quantum dots in a germanium/silicon germanium heterostructure. The results of the most important experiments are concerned with distributing quantum information: either by entangling three qubits as the basis for the phase...doctoral thesis 2024
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Ciani, Alessandro (author), DiVincenzo, David P. (author), Terhal, B.M. (author)During the last 30 years, stimulated by the quest to build superconducting quantum processors, a theory of quantum electrical circuits has emerged, which is called circuit quantum electrodynamics or circuit-QED. The goal of the theory is to provide a quantum description of the most relevant degrees of freedom. The central objects to be derived...book 2024
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Ockhorst, R. (author), Koopman, L. (author), Pols, C.F.J. (author)For the start of a secondary school level lesson series on quantum computing, we designed a hands-on modeling activity where students construct a model diamond lattice with a nitrogen vacancy (NV) defect. NV centers find application as qubits and sensitive magnetometers. This activity aims to help students visualize the structure of such NV...journal article 2024
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Gong, J. (author)Quantum computers have gained widespread interest from both industry and academia in the last decade as they are very promising for solving problems intractable by classical computers. However, there is a limited number of qubits in current quantum processors, which impedes the practical applications of a quantum computer. To increase the number...doctoral thesis 2023
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Sagastizabal, R.E. (author)Superconducting qubits have seen a tremendous progress in the last two decades, and yet they remain unable to extract quantum advantage for application scenarios. While algorithms like Shor’s demonstrate quantum advantage in theory, they do not seem to fit modern noisy quantum processors. Then, in order to achieve quantum advantage either modern...doctoral thesis 2023
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Stein, Jonas (author), Ott, Dominik (author), Nüßlein, Jonas (author), Bucher, David (author), Schönfeld, Mirco (author), Feld, S. (author)The analysis of network structure is essential to many scientific areas ranging from biology to sociology. As the computational task of clustering these networks into partitions, i.e., solving the community detection problem, is generally NP-hard, heuristic solutions are indispensable. The exploration of expedient heuristics has led to the...journal article 2023
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Russ, M.F. (author), Philips, S.G.J. (author), Xue, X. (author), Vandersypen, L.M.K. (author)Semiconductor spin qubits demonstrated single-qubit gates with fidelities up to 99.9 % benchmarked in the single-qubit subspace. However, tomographic characterizations reveal non-negligible crosstalk errors in a larger space. Additionally, it was long thought that the two-qubit gate performance is limited by charge noise, which couples to the...journal article 2023
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Battistel, F. (author), Chamberland, C. (author), Johar, K. (author), Overwater, R.W.J. (author), Sebastiano, F. (author), Skoric, L. (author), Ueno, Y. (author), Usman, M. (author)Quantum computing is poised to solve practically useful problems which are computationally intractable for classical supercomputers. However, the current generation of quantum computers are limited by errors that may only partially be mitigated by developing higher-quality qubits. Quantum error correction (QEC) will thus be necessary to...review 2023
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Seskir, Zeki C. (author), Umbrello, S. (author), Coenen, Christopher (author), Vermaas, P.E. (author)As quantum technologies (QT) advance, their potential impact on and relation with society has been developing into an important issue for exploration. In this paper, we investigate the topic of democratization in the context of QT, particularly quantum computing. The paper contains three main sections. First, we briefly introduce different...journal article 2023
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Kiene, G. (author), Overwater, R.W.J. (author), Catania, Alessandro (author), Gunaputi Sreenivasulu, A.M. (author), Bruschi, Paolo (author), Charbon-Iwasaki-Charbon, E. (author), Babaie, M. (author), Sebastiano, F. (author)This article presents a two-times interleaved, loop-unrolled SAR analog-to-digital converter (ADC) operational from 300 down to 4.2 K. The 6-8-bit resolution and the sampling speed up to 1 GS/s are targeted at digitizing the multi-channel frequency-multiplexed input in a spin-qubit reflectometry readout for quantum computing. To optimize the...journal article 2023
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Gong, J. (author), Charbon-Iwasaki-Charbon, E. (author), Sebastiano, F. (author), Babaie, M. (author)This article presents the first cryogenic phase-locked loop (PLL) operating at 4.2 K. The PLL is designed for the control system of scalable quantum computers. The specifications of PLL are derived from the required control fidelity for a single-qubit operation. By considering the benefits and challenges of cryogenic operation, a dedicated...journal article 2023
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Corley-Wiciak, Cedric (author), Richter, Carsten (author), Zoellner, Marvin H. (author), Zaitsev, Ignatii (author), Manganelli, Costanza L. (author), Hendrickx, N.W. (author), Sammak, A. (author), Veldhorst, M. (author), Scappucci, G. (author)A strained Ge quantum well, grown on a SiGe/Si virtual substrate and hosting two electrostatically defined hole spin qubits, is nondestructively investigated by synchrotron-based scanning X-ray diffraction microscopy to determine all its Bravais lattice parameters. This allows rendering the three-dimensional spatial dependence of the six...journal article 2023
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Bhatnagar, Dhruv (author), Steinberg, M.A. (author), Elkouss Coronas, D. (author), Almudever, Carmen (author), Feld, S. (author)Flag-style fault-tolerance has become a linchpin in the realization of small fault-tolerant quantum-error correction experiments. The flag protocol's utility hinges on low qubit over-head, which is typically much smaller than in other approaches. However, as in most fault-tolerance protocols, the advantages of flag-style error correction come...conference paper 2023
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Kiene, G. (author), Overwater, R.W.J. (author), Babaie, M. (author), Sebastiano, F. (author)This paper presents a floating inverter amplifier (FIA) that performs high-linearity amplification and sampling while driving a 2<inline-formula> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> time-interleaved (TI) SAR ADC, operating from room temperature (RT) down to 4.2 K. The power-efficient FIA...journal article 2023
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Lawrie, W.I.L. (author)Quantum computers based on semiconductor quantum dots are proving promising contenders for large scale quantum information processing. In particular, group IV based semiconductor hosts containing an abundance of nuclear spin-zero isotopes have made considerable headway into fulfilling the requirements of a universal quantum computer. Silicon (Si...doctoral thesis 2022
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Tosti Balducci, G.B.L. (author), Chen, B. Y. (author), Möller, M. (author), Gerritsma, M.I. (author), De Breuker, R. (author)Structural mechanics is commonly modeled by (systems of) partial differential equations (PDEs). Except for very simple cases where analytical solutions exist, the use of numerical methods is required to find approximate solutions. However, for many problems of practical interest, the computational cost of classical numerical solvers running on...review 2022
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Moody, Galan (author), Sorger, Volker J. (author), Blumenthal, Daniel J. (author), Juodawlkis, Paul W. (author), Loh, William (author), Jones, Alex E. (author), Pingault, B.J. (author), Elshaari, Ali W. (author), Zwiller, Val (author)Integrated photonics will play a key role in quantum systems as they grow from few-qubit prototypes to tens of thousands of qubits. The underlying optical quantum technologies can only be realized through the integration of these components onto quantum photonic integrated circuits (QPICs) with accompanying electronics. In the last decade,...journal article 2022
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Gabor, Thomas (author), Rosenfeld, Marian Lingsch (author), Linnhoff-Popien, Claudia (author), Feld, S. (author)Quadratic unconstrained binary optimization (QUBO) has become the standard format for optimization using quantum computers, i.e., for both the quantum approximate optimization algorithm (QAOA) and quantum annealing (QA). We present a toolkit of methods to transform almost arbitrary problems to QUBO by (i) approximating them as a polynomial and...conference paper 2022
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Overwater, R.W.J. (author), Babaie, M. (author), Sebastiano, F. (author)Quantum error correction (QEC) is required in quantum computers to mitigate the effect of errors on physical qubits. When adopting a QEC scheme based on surface codes, error decoding is the most computationally expensive task in the classical electronic back-end. Decoders employing neural networks (NN) are well-suited for this task but their...journal article 2022
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Patra, B (author)Quantum computers can provide exponential speedup in solving certain computational problems pertaining to drug discovery, cybersecurity, weather forecasting, etc. Although a quantum computer with just 50-qubits has been shown to surpass the computing power of the best supercomputers in specific applications, millions of qubits would be required...doctoral thesis 2021