Andreev reflection spectroscopy in strongly paired superconductors
Abstract
Motivated by recent experiments on low-carrier-density superconductors, including twisted multilayer graphene, we study signatures of the BCS to BEC evolution in Andreev reflection spectroscopy. We establish that in a standard quantum point contact geometry, Andreev reflection in a BEC superconductor is unable to mediate a zero-bias conductance beyond e²/h per lead channel. This bound is shown to result from a duality that links the sub-gap conductance of BCS and BEC superconductors. We then demonstrate that sharp signatures of BEC superconductivity, including perfect Andreev reflection, can be recovered by tunneling through a suitably designed potential well. We propose various tunneling spectroscopy setups to experimentally probe this recovery.
Additional Information
Attribution 4.0 International (CC BY 4.0). We thank Mohit Randeria, Hyunjin Kim, Micha l Papaj, and Kevin Nuckolls for insightful discussions. This work was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative, Grant GBMF8682 (C.L. and É.L.-H.); the Army Research Office under Grant Award W911NF-17-1-0323; the Caltech Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation through Grant GBMF1250; and the Walter Burke Institute for Theoretical Physics at Caltech.Attached Files
Submitted - 2207.09494.pdf
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Additional details
- Eprint ID
- 116308
- Resolver ID
- CaltechAUTHORS:20220816-183023896
- GBMF8682
- Gordon and Betty Moore Foundation
- W911NF-17-1-0323
- Army Research Office (ARO)
- Institute for Quantum Information and Matter (IQIM)
- GBMF1250
- Gordon and Betty Moore Foundation
- Walter Burke Institute for Theoretical Physics, Caltech
- Created
-
2022-08-16Created from EPrint's datestamp field
- Updated
-
2023-06-21Created from EPrint's last_modified field
- Caltech groups
- Institute for Quantum Information and Matter, Walter Burke Institute for Theoretical Physics