We propose a semiconductor-superconductor hybrid device for realizing topological superconductivity and
Majorana zero modes consisting of a planar Josephson junction structure with periodically modulated junction
width. By performing a numerical analysis of the effective model describing the low-energy physics of the hybrid
structure, we demonstrate that the modulation of the junction width results in a substantial enhancement of the
topological gap and, consequently, of the robustness of the topological superconducting phase and associated
Majorana zero modes. This enhancement is due to the formation of minibands with strongly renormalized
effective parameters, including stronger spin-orbit coupling, generated by the effective periodic potential induced
by the modulated structure. In addition to a larger topological gap, the proposed device supports a topological
superconducting phase that covers a significant fraction of the parameter space, including the low Zeeman field
regime, in the absence of a superconducting phase difference across the junction. Furthermore, the optimal
regime for operating the device can be conveniently accessed by tuning the potential in the junction region
using, for example, a top gate.
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Periodic dynamics in superconductors induced by an impulsive optical quench
Abstract A number of experiments have evidenced signatures of enhanced superconducting correlations after photoexcitation. Initially, these experiments were interpreted as resulting from quasi-static changes in the Hamiltonian parameters, for example, due to lattice deformations or melting of competing phases. Yet, several recent observations indicate that these conjectures are either incorrect or do not capture all the observed phenomena, which include reflectivity exceeding unity, large shifts of Josephson plasmon edges, and appearance of new peaks in terahertz reflectivity. These observations can be explained from the perspective of a Floquet theory involving a periodic drive of system parameters, but the origin of the underlying oscillations remains unclear. In this paper, we demonstrate that following incoherent photoexcitation, long-lived oscillations are generally expected in superconductors with low-energy Josephson plasmons, such as in cuprates or fullerene superconductor K 3 C 60 . These oscillations arise from the parametric generation of plasmon pairs due to pump-induced perturbation of the superconducting order parameter. We show that this bi-plasmon response can persist even above the transition temperature as long as strong superconducting fluctuations are present. Our analysis offers a robust framework to understand light-induced superconducting behavior, and the predicted bi-plasmon oscillations can be directly detected using available experimental techniques.
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- Award ID(s):
- 2116679
- NSF-PAR ID:
- 10429839
- Date Published:
- Journal Name:
- Communications Physics
- Volume:
- 5
- Issue:
- 1
- ISSN:
- 2399-3650
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s42005-022-01007-w
