Publications (55)
Anharmonicity of a Gatemon Qubit with a Few-Mode Josephson Junction
A. Kringhøj, L. Casparis, M. Hell +8
Coherent operation of gate-voltage-controlled hybrid transmon qubits (gatemons) based on semiconductor nanowires was recently demonstrated. Here we experimentally investigate the a…
Raman spectroscopy and electrical properties of InAs nanowires with local oxidation enabled by substrate micro-trenches and laser irradiation
R. Tanta, M. H. Madsen, Z. Liao +4
The thermal gradient along indium-arsenide nanowires was engineered by a combination of fabricated micro- trenches in the supporting substrate and focused laser irradiation. This a…
Two-Impurity Yu-Shiba-Rusinov States in Coupled Quantum Dots
J. C. Estrada Saldaña, A. Vekris, R. Žitko +5
Using double quantum dots as the weak link of a Josephson junction, we realize the superconducting analog of the celebrated two-impurity Kondo model. The device shows a cusped curr…
Dynamical polarization of the fermion parity in a nanowire Josephson junction
J. J. Wesdorp, L. Grünhaupt, A. Vaartjes +6
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 j…
Evolution of Nanowire Transmons and Their Quantum Coherence in Magnetic Field
F. Luthi, T. Stavenga, O. W. Enzing +8
We present an experimental study of nanowire transmons at zero and applied in-plane magnetic field. With Josephson non-linearities provided by the nanowires, our qubits operate at…
Evidence for spin-polarized bound states in semiconductor-superconductor-ferromagnetic insulator islands
S. VaitiekÄnas, R. Seoane Souto, Y. Liu +4
We report Coulomb blockade transport studies of semiconducting InAs nanowires grown with epitaxial superconducting Al and ferromagnetic insulator EuS on overlapping facets. Compari…
Ground state phase diagram and "parity flipping'' microwave transitions in a gate-tunable Josephson Junction
M. R. Sahu, F. J. Matute-Cañadas, M. Benito +6
We probed a gate-tunable InAs nanowire Josephson weak link by coupling it to a microwave resonator. Tracking the resonator frequency shift when the weak link is close to pinch-off,…
Integrated bioelectronic proton-gated logic elements utilizing nanoscale patterned Nafion
J. G. Gluschke, J. Seidl, R. W. Lyttleton +9
A central endeavour in bioelectronics is the development of logic elements to transduce and process ionic to electronic signals. Motivated by this challenge, we report fully monoli…
Microwave spectroscopy of interacting Andreev spins
J. J. Wesdorp, F. J. Matute-CaÅadas, A. Vaartjes +13
Andreev bound states are fermionic states localized in weak links between superconductors which can be occupied with spinful quasiparticles. Microwave experiments using superconduc…
InAs nanowire with epitaxial aluminium as a single-electron transistor with fixed tunnel barriers
M. Taupin, E. Mannila, P. Krogstrup +6
We report on fabrication of single-electron transistors using InAs nanowires with epitaxial aluminium with fixed tunnel barriers made of aluminium oxide. The devices exhibit a hard…
Direct microwave measurement of Andreev-bound-state dynamics in a proximitized semiconducting nanowire
M. Hays, G. de Lange, K. Serniak +6
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…
Epitaxy of Semiconductor-Superconductor nanowires
P. Krogstrup, N. L. B. Ziino, W. Chang +6
Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semicond…
Microwave susceptibility observation of interacting many-body Andreev states
V. Fatemi, P. D. Kurilovich, M. Hays +10
Electrostatic charging affects the many-body spectrum of Andreev states, yet its influence on their microwave properties has not been elucidated. We developed a circuit quantum ele…
Supercurrent transport through 1-periodic full-shell Coulomb islands
D. Razmadze, R. Seoane Souto, E. C. T. O'Farrell +4
We experimentally investigate supercurrent through Coulomb islands, where island and leads are fabricated from semiconducting nanowires with fully surrounding superconducting shell…
Electrostatic control of quasiparticle poisoning in a hybrid semiconductor-superconductor island
H. Q. Nguyen, D. Sabonis, D. Razmadze +8
The performance of superconducting devices is often degraded by the uncontrolled appearance and disappearance of quasiparticles, a process known as poisoning. We demonstrate electr…
Flux-induced Majorana modes in full-shell nanowires
S. VaitiekÄnas, M. -T. Deng, P. Krogstrup +1
We demonstrate a novel means of creating Majorana zero modes using magnetic flux applied to a full superconducting shell surrounding a semiconducting nanowire core, unifying approa…
Hybrid nanowire ion-to-electron transducers for integrated bioelectronic circuitry
D. J. Carrad, A. B. Mostert, A. R. Ullah +8
A key task in the emerging field of bioelectronics is the transduction between ionic/protonic and electronic signals at high fidelity. This is a considerable challenge since the tw…
Coherent manipulation of an Andreev spin qubit
M. Hays, V. Fatemi, D. Bouman +9
Two promising architectures for solid-state quantum information processing are electron spins in semiconductor quantum dots and the collective electromagnetic modes of superconduct…
Controlled DC Monitoring of a Superconducting Qubit
A. Kringhøj, T. W. Larsen, B. van Heck +7
Creating a transmon qubit using semiconductor-superconductor hybrid materials not only provides electrostatic control of the qubit frequency, it also allows parts of the circuit to…
Supercurrent in a double quantum dot
J. C. Estrada Saldaña, A. Vekris, G. Steffensen +5
We demonstrate the Josephson effect in a serial double quantum dot defined in a nanowire with epitaxial superconducting leads. The supercurrent stability diagram adopts a honeycomb…
Effective g-factor in Majorana Wires
S. VaitiekÄnas, M. T. Deng, J. NygÃ¥rd +2
We use the effective g-factor of subgap states, g*, in hybrid InAs nanowires with an epitaxial Al shell to investigate how the superconducting density of states is distributed betw…
Quantum-Dot Parity Effects in Trivial and Topological Josephson Junctions
D. Razmadze, E. C. T. O'Farrell, P. Krogstrup +1
An odd-occupied quantum dot in a Josephson junction can flip transmission phase, creating a Ï-junction. When the junction couples topological superconductors, no phase flip is exp…
Hard gap in epitaxial semiconductor-superconductor nanowires
W. Chang, S. M. Albrecht, T. S. Jespersen +4
Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunneling rates, the hallmark of semiconductor devices. On…
Nonlocality of Majorana Modes in Hybrid Nanowires
M. T. Deng, S. Vaitiekénas, E. Prada +5
Spatial separation of Majorana zero modes distinguishes trivial from topological midgap states and is key to topological protection in quantum computing applications. Although sign…
Anomalous Metallic Phase in Tunable Destructive Superconductors
S. VaitiekÄnas, P. Krogstrup, C. M. Marcus
Multiply connected superconductors smaller than the coherence length show destructive superconductivity, characterized by reentrant quantum phase transitions driven by magnetic flu…
Epitaxial aluminum contacts to InAs nanowires
N. L. B. Ziino, P. Krogstrup, M. H. Madsen +5
We report a method for making epitaxial superconducting contacts to semiconducting nanowires. The temperature and gate characteristics demonstrate barrier-free electrical contact,…
Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
F. J. Matute-Cañadas, C. Metzger, Sunghun Park +7
We performed microwave spectroscopy of an InAs nanowire between superconducting contacts implementing a finite-length, multi-channel Josephson weak link. Certain features in the sp…
Selective Area Grown Semiconductor-Superconductor Hybrids: A Basis for Topological Networks
S. VaitiekÄnas, A. M. Whiticar, M. T. Deng +8
We introduce selective area grown hybrid InAs/Al nanowires based on molecular beam epitaxy, allowing arbitrary semiconductor-superconductor networks containing loops and branches.…
Electronic properties of InAs/EuS/Al hybrid nanowires
Chun-Xiao Liu, Sergej Schuwalow, Yu Liu +4
We study the electronic properties of InAs/EuS/Al heterostructures as explored in a recent experiment [S. Vaitiekenas \emph{et al.}, Nat. Phys. (2020)], combining both spectroscopi…
Two-dimensional epitaxial superconductor-semiconductor heterostructures: A platform for topological superconducting networks
J. Shabani, M. Kjaergaard, H. J. Suominen +12
Progress in the emergent field of topological superconductivity relies on synthesis of new material combinations, combining superconductivity, low density, and spin-orbit coupling…
A Semiconductor Nanowire-Based Superconducting Qubit
T. W. Larsen, K. D. Petersson, F. Kuemmeth +4
We introduce a hybrid qubit based on a semiconductor nanowire with an epitaxially grown superconductor layer. Josephson energy of the transmon-like device ("gatemon") is controlled…
Supercurrent reversal in ferromagnetic hybrid nanowire Josephson junctions
D. Razmadze, R. Seoane Souto, L. Galletti +7
We report supercurrent transport measurements in hybrid Josephson junctions comprised of semiconducting InAs nanowires with epitaxial ferromagnetic insulator EuS and superconductin…
Near-thermal limit gating in heavily-doped III-V semiconductor nanowires using polymer electrolytes
A. R. Ullah, D. J. Carrad, P. Krogstrup +2
Doping is a common route to reducing nanowire transistor on-resistance but has limits. High doping level gives significant loss in gate performance and ultimately complete gate fai…
Hybrid Double Quantum Dots: Normal, Superconducting, and Topological Regimes
D. Sherman, J. S. Yodh, S. M. Albrecht +3
Epitaxial semiconductor-superconductor hybrid materials are an excellent basis for studying mesoscopic and topological superconductivity, as the semiconductor inherits a hard super…
Parity lifetime of bound states in a proximitized semiconductor nanowire
A. P. Higginbotham, S. M. Albrecht, G. Kirsanskas +7
Quasiparticle excitations can compromise the performance of superconducting devices, causing high frequency dissipation, decoherence in Josephson qubits, and braiding errors in pro…
Zero-field Topological Superconductivity in Ferromagnetic Hybrid Nanowires
S. VaitiekÄnas, Y. Liu, P. Krogstrup +1
We report transport measurements and tunneling spectroscopy in hybrid nanowires with epitaxial layers of superconducting Al and the ferromagnetic insulator EuS, grown on semiconduc…
Voltage-Controlled Superconducting Quantum Bus
L. Casparis, N. J. Pearson, A. Kringhøj +6
We demonstrate the ability of an epitaxial semiconductor-superconductor nanowire to serve as a field-effect switch to tune a superconducting cavity. Two superconducting gatemon qub…
Spin-orbit splitting of Andreev states revealed by microwave spectroscopy
L. Tosi, C. Metzger, M. F. Goffman +6
We have performed microwave spectroscopy of Andreev states in superconducting weak links tailored in an InAs-Al (core-full shell) epitaxially-grown nanowire. The spectra present di…
Realizing Majorana zero modes in superconductor-semiconductor heterostructures
R. M. Lutchyn, E. P. A. M. Bakkers, L. P. Kouwenhoven +3
Realizing topological superconductivity and Majorana zero modes in the laboratory is one of the major goals in condensed matter physics. We review the current status of this rapidl…
Gatemon Benchmarking and Two-Qubit Operation
L. Casparis, T. W. Larsen, M. S. Olsen +5
Recent experiments have demonstrated superconducting transmon qubits with semiconductor nanowire Josephson junctions. These hybrid gatemon qubits utilize field effect tunability ch…
p-GaAs nanowire MESFETs with near-thermal limit gating
A. R. Ullah, F. Meyer, J. G. Gluschke +5
Difficulties in obtaining high-performance p-type transistors and gate insulator charge-trapping effects present two major challenges for III-V complementary metal-oxide semiconduc…
Flux-induced topological superconductivity in full-shell nanowires
S. VaitiekÄnas, G. W. Winkler, B. van Heck +8
We present a novel route to realizing topological superconductivity using magnetic flux applied to a full superconducting shell surrounding a semiconducting nanowire core. In the d…
Conduction Channels of an InAs-Al nanowire Josephson weak link
M. F. Goffman, C. Urbina, H. Pothier +3
We present a quantitative characterization of an electrically tunable Josephson junction defined in an InAs nanowire proximitized by an epitax-ially-grown superconducting Al shell.…
Spin-split superconductivity in spin-orbit coupled hybrid nanowires with ferromagnetic barriers
J. Zhao, A. Mazanik, D. Razmadze +4
We report transport studies of hybrid Josephson junctions based on semiconducting InAs nanowires with fully overlapping epitaxial ferromagnetic insulator EuS and superconducting Al…
Continuous monitoring of a trapped, superconducting spin
M. Hays, V. Fatemi, K. Serniak +7
Readout and control of fermionic spins in solid-state systems are key primitives of quantum information processing and microscopic magnetic sensing. The highly localized nature of…
Parity switching in a full-shell superconductor-semiconductor nanowire qubit
O. Erlandsson, D. Sabonis, A. Kringhøj +4
The rate of charge-parity switching in a full-shell superconductor-semiconductor nanowire qubit is measured by directly monitoring the dispersive shift of a readout resonator. At z…
Transport signatures of quasiparticle poisoning in a Majorana island
S. M. Albrecht, E. B. Hansen, A. P. Higginbotham +7
We investigate effects of quasiparticle poisoning in a Majorana island with strong tunnel coupling to normal-metal leads. In addition to the main Coulomb blockade diamonds, "shadow…
Exponential Protection of Zero Modes in Majorana Islands
S. M. Albrecht, A. P. Higginbotham, M. Madsen +5
Majorana zero modes are quasiparticle excitations in condensed matter systems that have been proposed as building blocks of fault-tolerant quantum computers [1]. They are expected…
Suppressed Charge Dispersion via Resonant Tunneling in a Single-Channel Transmon
A. Kringhøj, B. van Heck, T. W. Larsen +6
We demonstrate strong suppression of charge dispersion in a semiconductor-based transmon qubit across Josephson resonances associated with a quantum dot in the junction. On resonan…
Magnetic-Field-Compatible Superconducting Transmon Qubit
A. Kringhøj, T. W. Larsen, O. Erlandsson +8
We present a hybrid semiconductor-based superconducting qubit device which remains coherent at magnetic fields up to 1 T. The qubit transition frequency exhibits periodic oscillati…
A Parity-Protected Superconductor-Semiconductor Qubit
T. W. Larsen, M. E. Gershenson, L. Casparis +7
Coherence of superconducting qubits can be improved by implementing designs that protect the parity of Cooper pairs on superconducting islands. Here, we introduce a parity-protecte…
Majorana bound states in a coupled quantum-dot hybrid-nanowire system
M. T. Deng, S. Vaitiekenas, E. B. Hansen +6
Hybrid nanowires combining semiconductor and superconductor materials appear well suited for the creation, detection, and control of Majorana bound states (MBSs). We demonstrate th…
Absolute dimensions of eclipsing binaries. XXVIII. BK Pegasi and other F-type binaries: Prospects for calibration of convective core overshoot
J. V. Clausen, S. Frandsen, H. Bruntt +5
We present a detailed study of the F-type detached eclipsing binary BK Peg, based on new photometric and spectroscopic observations. The two components, which have evolved to the u…
Towards low-dimensional hole systems in Be-doped GaAs nanowires
A. R. Ullah, J. G. Gluschke, P. Krogstrup +3
GaAs was central to the development of quantum devices but is rarely used for nanowire-based quantum devices with InAs, InSb and SiGe instead taking the leading role. p-type GaAs n…
Andreev Modes from Phase Winding in a Full-shell Nanowire-based Transmon
A. Kringhøj, G. W. Winkler, T. W. Larsen +6
We investigate transmon qubits made from semiconductor nanowires with a fully surrounding superconducting shell. In the regime of reentrant superconductivity associated with the de…