Publications
Updated lists of publications are available online:
Google Scholar:
https://scholar.google.com/citations?user=4f0O4R0AAAAJ&hl=ja&oi=ao
Researcher ID:
http://www.researcherid.com/rid/B-8163-2013
Highlight of recent papers
1. Superconducting proximity effect in a quantum anomalous Hall insulator
Anjana Uday, Gertjan Lippertz, Kristof Moors, Henry F. Legg, Rikkie Joris, Andrea Bliesener, Lino M. C. Pereira, A. A. Taskin, and Yoichi Ando, Induced superconducting correlations in a quantum anomalous Hall insulator, Nature Phys. 20 (2024) 1589-1595.
We have recently succeeded in proximitizing the Quantum anomalous Hall insulator (QAHI) in V-doped (Bi,Sb)2Te3, which was evinced in the crossed Andreev-reflection (CAR) signal across the Nb finger electrode contacting the chiral edge state of the QAHI shown in (b). In our device, perfectly quantized Hall resistance was observed with the Nb finger electrode as the drain. A negative nonlocal downstream resistance was observed when niobium is in the superconducting (SC) state as shown in (c), which is only possible when CAR converts impinging electrons into holes in the downstream edge. Such a CAR process induces SC correlations in the chiral edge states. Furthermore, the finger-width dependence of the CAR signal indicates that the QAHI surface is proximitized, which suggests that topological superconductivity is induced on the QAHI surface. This breakthrough allows us to conceive further experiments to address chiral Majorana fermions and Majorana zero modes based on the QAHI platform.
2. Andreev bound states and crossed Andreev reflection in a proximitized TI nanowire
Junya Feng, Henry F. Legg, Mahasweta Bagchi, Daniel Loss, Jelena Klinovaja, and Yoichi Ando, Long-range crossed Andreev reflection in a topological insulator nanowire proximitized by a superconductor, Nature Phys. (2025), DOI: 10.1038/s41567-025-02806-y.
Very recently, we found that metallic electrodes made on a clean TI nanowire modulates the chemical potential underneath and creates a potential well in the wire; when such electrodes are superconducting, they create Andreev bound states (ABS) in the bare portion of the TI nanowire, opening a hard gap. Interestingly, the normal Fabry-Perot resonance in this bare portion of the TI nanowire competes with the ABS and creates a periodic gap closing and reopening. With the nonlocal transport measurement technique, we discovered a surprisingly long-range crossed Andreev reflection in this type of device.
3. Parity readout technology using c-QED
J. Krause, G. Marchegiani, L. M. Janssen, G. Catelani, Yoichi Ando, and C. Dickel, Quasiparticle effects in magnetic-field-resilient three-dimensional transmons,Phys. Rev. Appl. 22 (2024) 044063.
Based on the fabrication and operation technologies of superconducting transmon qubits established in our lab, we have recently demonstrated a parity readout protocol for a transmon qubit in a high magnetic field, which is an important technology for a Majorana qubit. We developed a parity mapping scheme using the 1st and 2nd excited transmon states. Using the parity-dependent charge dispersion of the excitation energy to the 1st excited state shown in (b), we obtained Parallel-magnetic-field dependence of the measured lifetime of even and odd parities shown in (c). The parity lifetime of our transmon device shows an interesting magnetic field dependence and is longer than 0.4 ms even in 0.4 T.
