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Wesdorp, J.J. (author), Grünhaupt, L. (author), Vaartjes, A. (author), Pita-Vidal, Marta (author), Bargerbos, A. (author), Splitthoff, L.J. (author), Krogstrup, P. (author), van Heck, B. (author), de Lange, G. (author)Josephson junctions in InAs nanowires proximitized with an Al shell can host gate-tunable Andreev bound states. Depending on the bound state occupation, the fermion parity of the junction can be even or odd. Coherent control of Andreev bound states has recently been achieved within each parity sector, but it is impeded by incoherent parity...journal article 2023
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Wang, Guanzhong (author), Dvir, T. (author), van Loo, N. (author), Mazur, G.P. (author), Gazibegovic, Sasa (author), Badawy, G.H.A. (author), Bakkers, Erik P.A.M. (author), Kouwenhoven, Leo P. (author), de Lange, G. (author)The lowest-energy excitations of superconductors do not carry an electric charge, as their wave function is equally electron-like and hole-like. This fundamental property is not easy to study in electrical measurements that rely on the charge to generate an observable signal. The ability of a quantum dot to act as a charge filter enables us...journal article 2022
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Wang, Q. (author), Khosropanah, P. (author), Van Der Kuur, J. (author), de Lange, G. (author), Audley, M. D. (author), Aminaei, A. (author), Ilyas, S. (author), van der Tak, F.M. (author), Gao, J.R. (author)We demonstrate multiplexed readout of 43 transition edge sensor (TES) bolometers operating at 90 mK using a frequency division multiplexing (FDM) readout chain with bias frequencies ranging from 1 to 3.5 MHz and a typical frequency spacing of 32 kHz. We improve the previously reported performance of our FDM system by two important steps....journal article 2022
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Wang, Q. (author), Khosropanah, P. (author), Van Der Kuur, J. (author), de Lange, G. (author), Audley, M. D. (author), Aminaei, A. (author), Ridder, M.L. (author), Van Der Linden, A. J. (author), Bruijn, M. P. (author), Gao, J.R. (author)We demonstrate multiplexing readout of 60 transition edge sensor (TES) bolometers operating at 90 mK using a frequency division multiplexing readout chain with bias frequencies ranging from 1 to 3.5 MHz and with a typical frequency spacing of 32 kHz. The readout chain starts with a two-stage SQUID amplifier and has a noise level of 9.5 pA/ Hz...journal article 2021
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Bargerbos, A. (author), Uilhoorn, W. (author), Yang, C. (author), Krogstrup, Peter (author), Kouwenhoven, Leo P. (author), de Lange, G. (author), van Heck, B. (author), Kou, A. (author)Isolation from the environment determines the extent to which charge is confined on an island, which manifests as Coulomb oscillations, such as charge dispersion. We investigate the charge dispersion of a nanowire transmon hosting a quantum dot in the junction. We observe rapid suppression of the charge dispersion with increasing junction...journal article 2020
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Pita-Vidal, Marta (author), Bargerbos, A. (author), Yang, C. (author), van Woerkom, D.J. (author), Pfaff, W. (author), Haider, S.N. (author), Krogstrup, Peter (author), Kouwenhoven, Leo P. (author), de Lange, G. (author), Kou, A. (author)Hybrid superconducting circuits, which integrate nonsuperconducting elements into a circuit quantum electrodynamics (cQED) architecture, expand the possible applications of cQED. Building hybrid circuits that work in large magnetic fields presents even further possibilities, such as the probing of spin-polarized Andreev bound states and the...journal article 2020
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Hays, M. (author), de Lange, G. (author), Serniak, K. (author), van Woerkom, D.J. (author), Bouman, D. (author), Krogstrup, P. (author), Nygård, J. (author), Geresdi, A. (author), Devoret, M. H. (author)The modern understanding of the Josephson effect in mesosopic devices derives from the physics of Andreev bound states, fermionic modes that are localized in a superconducting weak link. Recently, Josephson junctions constructed using semiconducting nanowires have led to the realization of superconducting qubits with gate-tunable Josephson...journal article 2018
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Serniak, K. (author), Hays, M. (author), de Lange, G. (author), Diamond, S. (author), SHANKAR, S. (author), Burkhart, L. D. (author), Frunzio, L. (author), Houzet, M. (author), Devoret, M. H. (author)Nonequilibrium quasiparticle excitations degrade the performance of a variety of superconducting circuits. Understanding the energy distribution of these quasiparticles will yield insight into their generation mechanisms, the limitations they impose on superconducting devices, and how to efficiently mitigate quasiparticle-induced qubit...journal article 2018
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De Lange, G. (author), Van Heck, B. (author), Bruno, A. (author), Van Woerkom, D.J. (author), Geresdi, A. (author), Plissard, S.R. (author), Bakkers, E.P.A.M. (author), Akhmerov, A.R. (author), Di Carlo, L. (author)We report the realization of quantum microwave circuits using hybrid superconductor-semiconductor Josephson elements comprised of InAs nanowires contacted by NbTiN. Capacitively shunted single elements behave as transmon circuits with electrically tunable transition frequencies. Two-element circuits also exhibit transmonlike behavior near zero...journal article 2015
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Bruno, A. (author), De Lange, G. (author), Asaad, S. (author), Van der Enden, K.L. (author), Langford, N.K. (author), DiCarlo, L. (author)We present microwave-frequency NbTiN resonators on silicon, systematically achieving internal quality factors above 1?M in the quantum regime. We use two techniques to reduce losses associated with two-level systems: an additional substrate surface treatment prior to NbTiN deposition to optimize the metal-substrate interface and deep reactive...journal article 2015
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De Lange, G. (author), Riste, D. (author), Tiggelman, M.J. (author), Eichler, C. (author), Tornberg, L. (author), Johansson, G. (author), Wallraff, A. (author), Schouten, R.N. (author), DiCarlo, L. (author)We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model...journal article 2014
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Saira, O.P. (author), Groen, J.P. (author), Cramer, J. (author), Meretska, M. (author), De Lange, G. (author), DiCarlo, L. (author)We present an indirect two-qubit parity meter in planar circuit quantum electrodynamics, realized by discrete interaction with an ancilla and a subsequent projective ancilla measurement with a dedicated, dispersively coupled resonator. Quantum process tomography and successful entanglement by measurement demonstrate that the meter is...journal article 2014
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Ranjan, V. (author), De Lange, G. (author), Schutjens, R. (author), Debelhoir, T. (author), Groen, J.P. (author), Szombati, D. (author), Thoen, D.J. (author), Klapwijk, T.M. (author), Hanson, R. (author), DiCarlo, L. (author)We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25–1.2 K) and polarizing magnetic field (80–300 mT). Measurements exploit field-controlled coupling of the ensemble to two modes of a transmission-line resonator. The observed temperature-independent spin relaxation time...journal article 2013
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De Lange, G. (author)The field of quantum science and technology has generated many ideas for new revolutionary devices that exploit the quantum mechanical properties of small-scale systems. Isolated solid state spins play a large role in quantum technologies. They can be used as basic building blocks for a quantum computer or as ultra-sensitive magnetic-field...doctoral thesis 2012
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Wang, Z.H. (author), De Lange, G. (author), Riste, D. (author), Hanson, R. (author), Dobrovitski, V.V. (author)We perform a detailed theoretical-experimental study of the dynamical decoupling (DD) of the nitrogen-vacancy (NV) center in diamond. We investigate the DD sequences applied to suppress the dephasing of the electron spin of the NV center induced by the coupling to a spin bath composed of the substitutional nitrogen atoms. The decoupling...journal article 2012
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Hayton, D.J. (author), Gao, J.R. (author), Kooi, J.W. (author), Ren, Y. (author), Zhang, W. (author), De Lange, G. (author)We report on a method to stabilize a hot electron bolometer (HEB) mixer at 2.5 THz. The technique utilizes feedback control of the local oscillator (LO) laser power by means of a swing-arm actuator placed in the optical beam path. We demonstrate that this technique yields a factor of 50 improvement in the spectroscopic Allan variance time which...journal article 2012
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Audley, M.D. (author), De Lange, G. (author), Ferrari, L. (author), Gao, J.R. (author), Hijmering, R.A. (author), Khosropanah, P. (author), Lindeman, M. (author), Ridder, M.L. (author)We have constructed a test facility for characterizing the focal plane arrays of SAFARI, the far-infrared imaging spectrometer for the SPICA satellite. SAFARI’s three bolometer arrays are populated with extremely sensitive (NEP ? 2 × 10?19 W/? Hz) transition edge sensors with a transition temperature close to 100 mK. The extreme sensitivity and...journal article 2012
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De Lange, G. (author), Ristè, D. (author), Dobrovitski, V.V. (author), Hanson, R. (author)We experimentally demonstrate single-spin magnetometry with multipulse sensing sequences. The use of multipulse sequences can greatly increase the sensing time per measurement shot, resulting in enhanced ac magnetic field sensitivity. We theoretically derive and experimentally verify the optimal number of sensing cycles, for which the effects of...journal article 2011
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Dobrovitski, V.V. (author), De Lange, G. (author), Ristè, D. (author), Hanson, R. (author)Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit which cannot be prepared without perfect pulses. We present a protocol for pulse error analysis,...journal article 2010
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Van der Sar, T. (author), Heeres, E.C. (author), Dmochowski, G.M. (author), De Lange, G. (author), Robledo, L. (author), Oosterkamp, T.H. (author), Hanson, R. (author)Precise control over the position of a single quantum object is important for many experiments in quantum science and nanotechnology. We report on a technique for high-accuracy positioning of individual diamond nanocrystals. The positioning is done with a home-built nanomanipulator under real-time scanning electron imaging, yielding an accuracy...journal article 2009
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