Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D38: Semiconductor-Superconductor Hybrid StructuresRecordings Available
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Sponsoring Units: DQI Chair: Xiao Mi, Google Room: McCormick Place W-195 |
Monday, March 14, 2022 3:00PM - 3:12PM |
D38.00001: Two-qubit operation on gatemons using an AC gate voltage modulation of epitaxial superconductor-semiconductor junctions Yinqi Chen, Konstantin Nesterov, Vladimir Manucharyan, Hugh O Churchill, Javad Shabani, Maxim G Vavilov Tunable qubits have been proposed as a way to construct entangling gates that can be controlled by intrinsic parameters of the qubits. By keeping one of the qubit's frequency tunable through AC modulation, we can bring the sidebands of tunable qubit to a resonance with a state of another qubit effectively enhancing a two-qubit interaction. In particular, the modulation of the external flux for a tunable transmon was used to demonstrate entangling two-qubit gates [Didier et al., Phys. Rev. A 97, 022330 (2018)]. Inspired by this demonstration, we propose to apply a side gate AC voltage to epitaxial superconductor-semiconductor junctions of gatemon qubits. We demonstrate that high-fidelity two-bit operations are possible between pairs of capacitively coupled gatemons, when the side gate AC voltage changes the Josephson energy of the super-semi junction and generates a parametric resonance between the qubits. We also analyze performance of a two-qubit coupler with a super-semi junction modulated by an AC parametric drive. Our analysis demonstrates that the AC voltage control can be used to generate high-fidelity fast entangling operations with errors below 0.1%. |
Monday, March 14, 2022 3:12PM - 3:24PM |
D38.00002: Superconducting-semiconducting voltage-tunable qubits in the third dimension Thomas M Hazard, Andrew J Kerman, Kyle Serniak, Charles Tahan We propose superconducting-semiconducting qubit and coupler designs based on high-quality, compact through-silicon vias (TSVs). A "probe" chip is used to contact a sample chip with, for example, a superconductor-proximitized, epitaxially-grown, quantum well. By utilizing the capacitance of the TSVs on the probe chip, the majority of the electric field in the qubits is pulled away from lossy regions that are present in the semiconducting wafer. We find that the presence of the probe chip can reduce the qubit electric field participation in the sample wafer significantly. We also show how this scheme is extensible to multi-qubit systems which have tunable qubit-qubit couplings without magnetic fields. This approach promises to accelerate the understanding of super-semi heterostructures in a variety of systems. |
Monday, March 14, 2022 3:24PM - 3:36PM |
D38.00003: Probing microwave characteristics of InAs gatemon qubits with h-BN gate dielectrics William M Strickland Qubits on solid state devices could potentially provide the rapid control needed for scalable quantum information processors. Materials innovation and design breakthroughs constantly push the boundaries of qubit coherence and functionality of qubits over the past two decades. Semiconductor-superconductor devices offer a low-power tunable element which can be integrated into solid-state superconducting qubit architectures. However, losses attributed to the gate dielectric and underlying substrate must be limited in order to use these materials systems in state-of-the-art qubit circuits. Here we show that one can reliably fabricate voltage tunable qubits on Al-InAs materials system. We benchmark the performance of gatemon qubits (coherence, anharmonicity and coupling strengths) with an h-BN gate dielectric and compare them to qubits with conventional evaporated dielectrics. |
Monday, March 14, 2022 3:36PM - 3:48PM |
D38.00004: Gatemon qubits with superconductor-semiconductor-superconductor junctions: from high transparency to low transparency Charles Tahan, Utkan Gungordu, Kyle Serniak, Andrew J Kerman, Rusko Ruskov We consider gatemon qubits based on superconductor-semiconductor-superconductor Josephson junctions, whose properties can be tuned (via conduction channel transparency) with an electrostatic gate. Our theoretical approach builds on previous work, which focused on Andreev-level physics in the high-transparency regime, and aims to establish a rigorous physical correspondence with conventional transmon physics at low transparency, while remaining consistent with recent experimental data. Using our approach we investigate the qubit's full level structure, selection rules, and coherence properties, and the corresponding implications for qubit manipulation and measurement via a capacitively coupled superconducting resonator. |
Monday, March 14, 2022 3:48PM - 4:00PM |
D38.00005: Dynamical polarization of the fermion parity in a nanowire Josephson junction Jaap J Wesdorp, Lukas Gruenhaupt, Arjen Vaartjes, Marta Pita-Vidal, Arno Bargerbos, Lukas Johannes Splitthoff, Peter Krogstrup, Bernard van Heck, Gijs De Lange 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 is even or odd. Coherent control of Andreev bound states has recently been achieved within each parity sector, but it is impeded by incoherent parity switches due to excess quasiparticles in the superconducting environment. Here, we embed the junction in a superconducting LC resonator and show that we can polarize the fermion parity dynamically using microwave pulses. We demonstrate polarization up to 94% +- 1% (89% +- 1%) for the even (odd) parity as verified by single shot parity-readout. Finally, we apply this scheme to probe the flux-dependent transition spectrum of the even or odd parity sector selectively, without any post-processing or heralding. These results enable fast initialization of ABS parity and introduce an additional experimental control knob for studying parity switching processes, highly relevant for Andreev and topological qubits. |
Monday, March 14, 2022 4:00PM - 4:12PM |
D38.00006: Fortifying the strong-coupling regime of quantum dot circuit QED using high-impedance superconducting resonators Xuanzi Zhang, Zheyi Zhu, N. Phuan Ong, Jason R Petta In quantum dot cQED, the spin-photon coupling rate gs is proportional to the charge-photon coupling rate gc. To move deeper into the strong coupling regime, gc can be enhanced through the use of high kinetic inductance films. We report direct current resistivity measurements and microwave investigations of niobium nitride (NbN) films of different thicknesses. Consistent with expectations, the kinetic inductance increases rapidly as the film thickness is decreased below 50 nm. For 15 nm NbN thin films, we measured a large kinetic inductance of LK ∼ 41.2 pH/sq and sheet resistance of RS ~ 274 Ohm/sq. We investigate the use of these films in the fabrication of high impedance half-wavelength microwave cavities. |
Monday, March 14, 2022 4:12PM - 4:24PM |
D38.00007: Two Bogoliubov quasiparticles trapped by a spin in a hybrid superconductor-semiconductor nanowire Juan Carlos Estrada Saldaña, Alexandros Vekris, Luka Pavesic, Peter Krogstrup, Rok Zitko, Kasper Grove-Rasmussen, Jesper Nygård The binding of a single Bogoliubov quasiparticle (BQ) to a spin produces a singlet many-body state. Binding a second BQ to this spin would seem an impossible task, as the total spin is already zero. |
Monday, March 14, 2022 4:24PM - 4:36PM |
D38.00008: Nonlocal conductance spectroscopy of Andreev bound states in 2DEG-based nanowires Andreas Pöschl, Alisa Danilenko, Deividas Sabonis, Kaur Kristjuhan, Tyler Lindemann, Sergei Gronin, Geoffrey C Gardner, Candice Thomas, Michael J Manfra, Charles M Marcus We present experimental measurements of local and nonlocal tunneling spectroscopy of Andreev bound states in a hybrid superconductor-semiconductor three-terminal device based on a gate-defined InAs two-dimensional electron gas (2DEG) with an epitaxial Al layer. Andreev bound states in a nanowire with 0.6 μm between probes are investigated as a function of parallel magnetic field. At magnetic fields of order 2 T, we observe low-energy Andreev bound states, which oscillate around zero bias as a function of gate voltage, as expected, revealing in the non-local signal the oscillating electron-hole character of the bound state, consistent with theoretical predictions [1,2]. |
Monday, March 14, 2022 4:36PM - 4:48PM |
D38.00009: Gate-voltage tunable kinetic inductance in proximitized nanowires Lukas Johannes Splitthoff, Arno Bargerbos, Lukas Grunhaupt, Marta Pita-Vidal, Jaap J Wesdorp, Yu Liu, Peter Krogstrup, Angela Kou, Christian Kraglund Andersen, Bernard van Heck Superconducting-semiconducting nanowires combine two frontiers of condensed matter in a hybrid state, which offers formidable possibilities for quantum computing and quantum sensing devices. In this talk, we study a quarter-wave coplanar waveguide resonator shunted by a hybrid Al-InAs nanowire. We show a gate voltage controllable resonance frequency and demonstrate a frequency shift of up to 8MHz. We relate the frequency shift to the change in kinetic inductance of the hybrid nanowire which arises from the gate-tunable hybridization of the superconductor to semiconductor interface. From our measurement result we extract the electron line density and the effective superconducting gap of the hybrid nanowire. The measurement technique demonstrated in this work complements existing characterization methods for hybrid nanowires and forms a promising path towards gate-controlled superconducting electronics. |
Monday, March 14, 2022 4:48PM - 5:00PM |
D38.00010: On-demand single Cooper pair splitting in hybrid quantum dot systems Christian G Prosko, Damaz De Jong, Lin Han, Filip K Malinowski, Yu Liu, Jonne V Koski, Wolfgang Pfaff Quantum dots have become ubiquitous in quantum processing applications to store quantum information and control the movement of charge. We report the implementation of a quantum dot device geometry in an InAs VLS nanowire that splits Cooper pairs on demand, detecting and retaining the resultant electrons. First, we identify the Cooper pair splitting charge transition using dispersive gate sensing at GHz frequencies. Second, we present results utilizing a quantum dot as an electron parity sensor without relying on external charge detectors. As part of a quadruple quantum dot system, we employ this sensor to detect parity changes resulting from electrons emerging from a superconducting island. Once augmented by spin manipulation capabilities, the measurement scheme presented enables conducting a Bell test on split Cooper pairs. |
Monday, March 14, 2022 5:00PM - 5:12PM |
D38.00011: Magnon-photon strong interaction with magnetic nanowires Sergio Martinez-Losa del Rincon, Ignacio Gimeno, Marcos Rubín, David Zueco, Fernando Luis, María Jose (Pepa) Martínez-Pérez Nanoscopic spin excitations in confined geometries open a wide range of opportunities both for fundamental investigations and for applications.An archetypal spin excitation is embodied in the magnetic vortex.In order to minimize the total magnetostatic energy in a mesoscopic disc, the magnetization curls clockwise or counter-clockwise, defining the vortex circulation. At the core, exchange interaction forces the magnetization to point up or down defining the vortex polarity. Magnetic vortices have been extensively investigated and exploited due to their stable non-uniform magnetization. |
Monday, March 14, 2022 5:12PM - 5:24PM |
D38.00012: Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions (Part I) Cyril Metzger, Francisco J Matute, Leandro Tosi, Sunghun Park, Marcelo Goffman, Cristian Urbina, Alfredo L Yeyati, Hugues Pothier I will report on microwave spectroscopy measurements performed on InAs nanowire weak links between superconductors. The properties of the weak link, like the Josephson supercurrent, arise from the localized Andreev states that form at the link. In semiconducting nanowires, the spin-orbit coupling leads to a spin-splitting of the Andreev states when a superconducting phase difference is applied across the weak link [1]. In our experiments, we use a circuit-QED setup to probe the spectrum of Andreev states: the weak link shifts the resonance frequency of a coupled microwave resonator [1-3]. The spin-splitting of the Andreev states gives rise to a distinct phase dependence of the transition lines [1]. In addition, the comparison between data and theory shows that an interacting model is needed to account for several spectral line. |
Monday, March 14, 2022 5:24PM - 5:36PM |
D38.00013: Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions (Part II) Francisco Jesús Matute Fdez.-Cañadas, Cyril Metzger, Sunghun Park, Leandro Tosi, Marcelo Goffman, Cristian Urbina, Hugues Pothier, Alfredo Levy Yeyati Hybrid semiconducting/superconducting nanostructures combined with circuit-QED techniques are allowing to explore superconducting proximity effects with an unprecedented degree of detail. For instance, these techniques have permitted to reveal the fine structure, due to spin-orbit interactions, of Andreev states in semiconducting nanowire Josephson junctions [1]. While some of the observed features of the microwave spectrum could be explained in terms of few channels non-interacting models [1-3], other expected transitions lines from these models could not be clearly identified and some other experimental features remained unexplained. |
Monday, March 14, 2022 5:36PM - 5:48PM |
D38.00014: Singlet-doublet transitions of a quantum dot Josephson junction revealed in a transmon circuit: ground state spectroscopy Marta Pita-Vidal, Arno Bargerbos, Rok Zitko, Jesus Avila, Lukas Johannes Splitthoff, Lukas Grunhaupt, Jaap J Wesdorp, Christian Kraglund Andersen, Yu Liu, Peter Krogstrup, Ramon Aguado, Angela Kou, Bernard van Heck Probing the mesoscopic physics of hybrid superconductor-semiconductor elements using a circuit quantum electrodynamics (cQED) architecture offers enhanced energy and time resolution compared to DC transport techniques, and allows for additional methods of coherent control. Here we investigate the parity phase diagram of a quantum dot with superconducting leads using a hybrid transmon architecture. Our device is composed of a transmon where the Josephson coupling is determined by a gate-controlled quantum dot defined in an InAs-Al nanowire. We map out the parity phase diagram as a function of several control parameters: plunger and tunnel gate voltages, external flux, and magnetic field applied parallel to the wire. The measured phase diagram boundaries are in excellent agreement with those predicted by a single-impurity Anderson model with superconducting leads. |
Monday, March 14, 2022 5:48PM - 6:00PM |
D38.00015: Singlet-doublet transitions of a quantum dot Josephson junction revealed in a transmon circuit: finite temperature transitions Arno Bargerbos, Marta Pita Vidal, Rok Zitko, Jesus Avila, Lukas Johannes Splitthoff, Lukas Grunhaupt, Jaap J Wesdorp, Christian K Andersen, Yu Liu, Peter Krogstrup, Ramon Aguado, Angela Kou, Bernard van Heck Probing the mesoscopic physics of hybrid superconductor-semiconductor elements using a circuit quantum electrodynamics (cQED) architecture offers enhanced energy and time resolution compared to DC transport techniques, and allows for additional methods of coherent control. Here we investigate the parity phase diagram of a quantum dot with superconducting leads using a hybrid transmon architecture. Our device is composed of a transmon where the Josephson coupling is determined by a gate-controlled quantum dot defined in an InAs-Al nanowire. |
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