TY  - JOUR
A1  - Vigliotti, Lucia
A1  - Calzona, Alessio
A1  - Traverso Ziani, Niccolò
A1  - Bergeret, F. Sebastian
A1  - Sassetti, Maura
A1  - Trauzettel, Björn
T1  - Effects of the spatial extension of the edge channels on the interference pattern of a helical Josephson junction
JF  - Nanomaterials
N2  - Josephson junctions (JJs) in the presence of a magnetic field exhibit qualitatively different interference patterns depending on the spatial distribution of the supercurrent through the junction. In JJs based on two-dimensional topological insulators (2DTIs), the electrons/holes forming a Cooper pair (CP) can either propagate along the same edge or be split into the two edges. The former leads to a SQUID-like interference pattern, with the superconducting flux quantum ϕ\(_0\) (where ϕ\(_0\)=h/2e) as a fundamental period. If CPs’ splitting is additionally included, the resultant periodicity doubles. Since the edge states are typically considered to be strongly localized, the critical current does not decay as a function of the magnetic field. The present paper goes beyond this approach and inspects a topological JJ in the tunneling regime featuring extended edge states. It is here considered the possibility that the two electrons of a CP propagate and explore the junction independently over length scales comparable to the superconducting coherence length. As a consequence of the spatial extension, a decaying pattern with different possible periods is obtained. In particular, it is shown that, if crossed Andreev reflections (CARs) are dominant and the edge states overlap, the resulting interference pattern features oscillations whose periodicity approaches 2ϕ\(_0\).
KW  - edge states
KW  - Josephson junctions
KW  - topological insulators
KW  - interference pattern
KW  - 2ϕ\(_0\) periodicity
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-304846
SN  - 2079-4991
VL  - 13
IS  - 3
ER  - 
TY  - JOUR
A1  - Deacon, R. S.
A1  - Wiedenmann, J.
A1  - Bocquillon, E.
A1  - Domínguez, F.
A1  - Klapwijk, T. M.
A1  - Leubner, P.
A1  - Brüne, C.
A1  - Hankiewicz, E. M.
A1  - Tarucha, S.
A1  - Ishibashi, K.
A1  - Buhmann, H.
A1  - Molenkamp, L. W.
T1  - Josephson Radiation from Gapless Andreev Bound States in HgTe-Based Topological Junctions
JF  - Physical Review X
N2  - Frequency analysis of the rf emission of oscillating Josephson supercurrent is a powerful passive way of probing properties of topological Josephson junctions. In particular, measurements of the Josephson emission enable the detection of topological gapless Andreev bound states that give rise to emission at half the Josephson frequency f\(_{J}\) rather than conventional emission at f\(_{J}\). Here, we report direct measurement of rf emission spectra on Josephson junctions made of HgTe-based gate-tunable topological weak links. The emission spectra exhibit a clear signal at half the Josephson frequency f\(_{J}\)/2. The linewidths of emission lines indicate a coherence time of 0.3–4 ns for the f\(_{J}\)/2 line, much shorter than for the f\(_{J}\) line (3–4 ns). These observations strongly point towards the presence of topological gapless Andreev bound states and pave the way for a future HgTe-based platform for topological quantum computation.
KW  - condensed matter physics
KW  - Josephson junctions
KW  - topological materials
KW  - gapless Andreev bound states
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170969
VL  - 7
IS  - 021011
ER  -