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Wesdorp, J.J. (author), Vaartjes, A. (author), Grünhaupt, L. (author), Roelofs, S.R. (author), Splitthoff, L.J. (author), Pita-Vidal, Marta (author), Bargerbos, A. (author), Kouwenhoven, Leo P. (author), Andersen, C.K. (author)Andreev bound states are fermionic states localized in weak links between superconductors which can be occupied with spinful quasiparticles. Microwave experiments using superconducting circuits with InAs/Al nanowire Josephson junctions have recently enabled probing and coherent manipulation of Andreev states but have remained limited to zero...journal article 2024
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Gül, Önder (author), Zhang, H. (author), Bommer, J.D.S. (author), de Moor, M.W.A. (author), Car, Diana (author), Plissard, Sébastien R. (author), Bakkers, E.P.A.M. (author), Geresdi, A. (author), Kouwenhoven, Leo P. (author)Correction to: Nature Nanotechnologyhttps://doi.org/10.1038/s41565-017-0032-8, published online 15 January 2018. The Letter reports Majorana signatures in hybrid InSb semiconductor nanowire–NbTiN superconductor devices. The devices exhibit a conductance plateau near the conductance quantum 2e<sup>2</sup>/h at bias voltages above the...journal article 2024
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van Driel, D. (author), Roovers, B. (author), Zatelli, F. (author), Bordin, A. (author), Wang, Guanzhong (author), van Loo, N. (author), Wolff, J.C. (author), Mazur, G.P. (author), Kouwenhoven, Leo P. (author), Dvir, T. (author)The proximity effect of superconductivity on confined states in semiconductors gives rise to various bound states such as Andreev bound states, Andreev molecules, and Majorana zero modes. While such bound states do not conserve charge, their fermion parity is a good quantum number. One way to measure parity is to convert it to charge first,...journal article 2024
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Bordin, A. (author), Li, Xiang (author), van Driel, D. (author), Wolff, J.C. (author), Wang, Q. (author), ten Haaf, S.L.D. (author), Wang, Guanzhong (author), van Loo, N. (author), Kouwenhoven, Leo P. (author), Dvir, T. (author)The formation of a topological superconducting phase in a quantum-dot-based Kitaev chain requires nearest neighbor crossed Andreev reflection and elastic cotunneling. Here, we report on a hybrid InSb nanowire in a three-site Kitaev chain geometry - the smallest system with well-defined bulk and edge - where two superconductor-semiconductor...journal article 2024
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Bargerbos, A. (author), Splitthoff, L.J. (author), Pita-Vidal, Marta (author), Wesdorp, J.J. (author), Liu, Yu (author), Krogstrup, Peter (author), Kouwenhoven, Leo P. (author), Andersen, C.K. (author), Grünhaupt, L. (author)Quantum error correction will be an essential ingredient in realizing fault-tolerant quantum computing. However, most correction schemes rely on the assumption that errors are sufficiently uncorrelated in space and time. In superconducting qubits, this assumption is drastically violated in the presence of ionizing radiation, which creates bursts...journal article 2023
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de Jong, D. (author), Prosko, C.G. (author), Han, L. (author), Malinowski, F.K. (author), Liu, Yu (author), Kouwenhoven, Leo P. (author), Pfaff, Wolfgang (author)Cooper pair splitters hold utility as a platform for investigating the entanglement of electrons in Cooper pairs, but probing splitters with voltage-biased Ohmic contacts prevents the retention of electrons from split pairs since they can escape to the drain reservoirs. We report the ability to controllably split and retain single Cooper...journal article 2023
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Kouwenhoven, K. (author), Fan, D. (author), Biancalani, Enrico (author), de Rooij, S.A.H. (author), Karim, A.T. (author), Smith, C.S. (author), Murugesan, Vignesh (author), Thoen, David (author), Baselmans, J.J.A. (author), de Visser, P.J. (author)Kinetic inductance detectors (KIDs) are superconducting energy-resolving detectors, sensitive to single photons from the near-infrared to ultraviolet. We study a hybrid KID design consisting of a β-phase tantalum (β-Ta) inductor and a Nb-Ti-N interdigitated capacitor. The devices show an average intrinsic quality factor Qi of 4.3×105±1.3×105....journal article 2023
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Bordin, A. (author), Wang, Guanzhong (author), Liu, Chun Xiao (author), ten Haaf, S.L.D. (author), van Loo, N. (author), Mazur, G.P. (author), Xu, D. (author), van Driel, D. (author), Zatelli, F. (author), Gazibegovic, Sasa (author), Badawy, Ghada (author), Bakkers, Erik P.A.M. (author), Wimmer, M.T. (author), Kouwenhoven, Leo P. (author), Dvir, T. (author)A short superconducting segment can couple attached quantum dots via elastic cotunneling (ECT) and crossed Andreev reflection (CAR). Such coupled quantum dots can host Majorana bound states provided that the ratio between CAR and ECT can be controlled. Metallic superconductors have so far been shown to mediate such tunneling phenomena, albeit...journal article 2023
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van Driel, D. (author), Wang, Guanzhong (author), Bordin, A. (author), van Loo, N. (author), Zatelli, F. (author), Mazur, G.P. (author), Xu, D. (author), Gazibegovic, Sasa (author), Badawy, Ghada (author), Bakkers, Erik P.A.M. (author), Kouwenhoven, Leo P. (author), Dvir, T. (author)Semiconductor nanowires coupled to superconductors can host Andreev bound states with distinct spin and parity, including a spin-zero state with an even number of electrons and a spin-1/2 state with odd-parity. Considering the difference in spin of the even and odd states, spin-filtered measurements can reveal the underlying ground state. To...journal article 2023
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Bargerbos, A. (author), Pita-Vidal, Marta (author), Žitko, Rok (author), Splitthoff, L.J. (author), Grünhaupt, L. (author), Wesdorp, J.J. (author), Liu, Yu (author), Kouwenhoven, Leo P. (author), Aguado, Ramón (author), Andersen, C.K. (author), Kou, Angela (author), van Heck, Bernard (author)We use a hybrid superconductor-semiconductor transmon device to perform spectroscopy of a quantum dot Josephson junction tuned to be in a spin-1/2 ground state with an unpaired quasiparticle. Because of spin-orbit coupling, we resolve two flux-sensitive branches in the transmon spectrum, depending on the spin of the quasiparticle. A finite...journal article 2023
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Han, L. (author), Chan, M. (author), de Jong, D. (author), Prosko, C.G. (author), Badawy, Ghada (author), Gazibegovic, Sasa (author), Bakkers, Erik P.A.M. (author), Kouwenhoven, Leo P. (author), Malinowski, F.K. (author), Pfaff, Wolfgang (author)Utilizing dispersive gate sensing (DGS), we investigate the spin-orbit field (BSO) orientation in a many-electron double quantum dot (DQD) defined in an InSb nanowire. While characterizing the interdot tunnel couplings, we find the measured dispersive signal depends on the electron-charge occupancy, as well as on the amplitude and orientation...journal article 2023
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Dvir, T. (author), Wang, Guanzhong (author), van Loo, N. (author), Liu, C. (author), Mazur, G.P. (author), Bordin, A. (author), ten Haaf, S.L.D. (author), van Driel, D. (author), Zatelli, F. (author), Li, X. (author), Malinowski, F.K. (author), Gazibegovic, Sasa (author), Badawy, G.H.A. (author), Bakkers, Erik P.A.M. (author), Wimmer, M.T. (author), Kouwenhoven, Leo P. (author)Majorana bound states constitute one of the simplest examples of emergent non-Abelian excitations in condensed matter physics. A toy model proposed by Kitaev shows that such states can arise at the ends of a spinless p-wave superconducting chain<sup>1</sup>. Practical proposals for its realization<sup>2,3</sup> require coupling neighbouring...journal article 2023
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Levajac, V. (author), Wang, Ji Yin (author), Sfiligoj, C. (author), Lemang, M.F. (author), Wolff, J.C. (author), Bordin, A. (author), Badawy, G.H.A. (author), Gazibegovic, Sasa (author), Bakkers, Erik P.A.M. (author), Kouwenhoven, Leo P. (author)Tunneling spectroscopy is widely used to examine the subgap spectra in semiconductor-superconductor nanostructures when searching for Majorana zero modes (MZMs). Typically, semiconductor sections controlled by local gates at the ends of hybrids serve as tunnel barriers. Besides detecting states only at the hybrid ends, such gate-defined...journal article 2023
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Pita-Vidal, Marta (author), Bargerbos, A. (author), Splitthoff, L.J. (author), Grünhaupt, L. (author), Wesdorp, J.J. (author), Liu, Yu (author), Kouwenhoven, Leo P. (author), van Heck, Bernard (author), Andersen, C.K. (author)Spin qubits in semiconductors are a promising platform for producing highly scalable quantum computing devices. However, it is difficult to realize multiqubit interactions over extended distances. Superconducting spin qubits provide an alternative by encoding a qubit in the spin degree of freedom of an Andreev level. These Andreev spin qubits...journal article 2023
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van Loo, N. (author), Mazur, G.P. (author), Dvir, T. (author), Wang, Guanzhong (author), Dekker, R.C. (author), Lemang, M.F. (author), Sfiligoj, C. (author), Bordin, A. (author), van Driel, D. (author), Kouwenhoven, Leo P. (author)The proximity effect in semiconductor-superconductor nanowires is expected to generate an induced gap in the semiconductor. The magnitude of this induced gap, together with the semiconductor properties like spin-orbit coupling and g-factor, depends on the coupling between the materials. It is predicted that this coupling can be adjusted...journal article 2023
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Levajac, V. (author), Mazur, G.P. (author), van Loo, N. (author), Borsoi, F. (author), Badawy, Ghada (author), Gazibegovic, Sasa (author), Bakkers, Erik P.A.M. (author), Heedt, S. (author), Kouwenhoven, Leo P. (author), Wang, J. (author)Semiconducting nanowire Josephson junctions represent an attractive platform to investigate the anomalous Josephson effect and detect topological superconductivity. However, an external magnetic field generally suppresses the supercurrent through hybrid nanowire junctions and significantly limits the field range in which the supercurrent...journal article 2023
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Kofos, A. (author), Ubacht, J. (author), Rukanova, B.D. (author), Korevaar, G. (author), Kouwenhoven, Norbert (author), Tan, Y. (author)Sustainability is high on the agendas of public and private organizations. Governments are setting targets for reducing the use of virgin raw materials in products and to eliminate waste. To accelerate the transition towards a Circular Economy (CE) policymakers are launching instruments. However, policy instruments, such as financial incentives...journal article 2022
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Kouwenhoven, K. (author), Elwakil, I. (author), van Wingerden, J. (author), Murugesan, V. (author), Thoen, David (author), Baselmans, J.J.A. (author), de Visser, P.J. (author)Typical materials for optical Microwave Kinetic Inductance Detetectors (MKIDs) are metals with a natural absorption of ∼ 30–50% in the visible and near-infrared. To reach high absorption efficiencies (90–100%) the KID must be embedded in an optical stack. We show an optical stack design for a 60 nm TiN film. The optical stack is modeled as...journal article 2022
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Mazur, G.P. (author), van Loo, N. (author), Wang, J. (author), Dvir, T. (author), Wang, Guanzhong (author), Korneychuk, S. (author), Borsoi, F. (author), Dekker, R.C. (author), Badawy, G.H.A. (author), Vinke, Peter (author), Quintero Perez, M. (author), Heedt, S. (author), Kouwenhoven, Leo P. (author)In superconducting quantum circuits, aluminum is one of the most widely used materials. It is currently also the superconductor of choice for the development of topological qubits. However, aluminum-based devices suffer from poor magnetic field compatibility. Herein, this limitation is resolved by showing that adatoms of heavy elements (e.g.,...journal article 2022
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Wang, Guanzhong (author), Dvir, T. (author), Mazur, G.P. (author), Liu, C. (author), van Loo, N. (author), ten Haaf, S.L.D. (author), Bordin, A. (author), Gazibegovic, Sasa (author), Badawy, G.H.A. (author), Bakkers, Erik P.A.M. (author), Wimmer, M.T. (author), Kouwenhoven, Leo P. (author)In most naturally occurring superconductors, electrons with opposite spins form Cooper pairs. This includes both conventional s-wave superconductors such as aluminium, as well as high-transition-temperature, d-wave superconductors. Materials with intrinsic p-wave superconductivity, hosting Cooper pairs made of equal-spin electrons, have not...journal article 2022