97 citations · 477 across the 24 of their papers we have counts for
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Macroscopic quantum tunneling in multigap superconducting Josephson junctions: Escape rate enhancement via quantum fluctuations of Josephson-Leggett mode
Yukihiro Ota, Masahiko Machida, Tomio Koyama
We theoretically study the macroscopic quantum tunneling (MQT) in a hetero Josephson junction formed by a conventional single-gap superconductor and a multi-gap one such as ${MgB}_…
Collective modes in multiband superfluids and superconductors: Multiple dynamical classes
Yukihiro Ota, Masahiko Machida, Tomio Koyama +1
One important way to characterize the states having a gauge symmetry spontaneously broken over multibands should be to look at their collective excitation modes. We find that a thr…
Shapiro Steps as a Direct Probe of -wave Symmetry in Multi-gap Superconducting Josephson Junctions
Yukihiro Ota, Masahiko Machida, Tomio Koyama
We theoretically study the Shapiro steps in a hetero Josephson junction made of a single-gap superconductor and a two-gap one. We find that an anomalous DC Josephson current is ind…
Ambegaokar-Baratoff relations of Josephson critical current in heterojunctions with multi-gap superconductors
Yukihiro Ota, Noriyuki Nakai, Hiroki Nakamura +5
An extension of the Ambegaokar-Baratoff relation to a superconductor-insulator-superconductor (SIS) Josephson junction with multiple tunneling channels is derived. Appling the resu…