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arXiv · 1311.0659

Non-local spectroscopy of Andreev bound states

Jens Schindele·Andreas Baumgartner·Romain Maurand·Markus Weiss·Christian Schönenberger
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Abstract

We experimentally investigate Andreev bound states (ABSs) in a carbon nanotube quantum dot (QD) connected to a superconducting Nb lead (S). A weakly coupled normal metal contact acts as a tunnel probe that measures the energy dispersion of the ABSs. Moreover we study the response of the ABS to non-local transport processes, namely Cooper pair splitting and elastic co-tunnelling, that are enabled by a second QD fabricated on the same nanotube on the opposite side of S. We find an appreciable non-local conductance with a rich structure, including a sign reversal at the ground state transition from the ABS singlet to a degenerate magnetic doublet. We describe our device by a simple rate equation model that captures the key features of our observations and demonstrates that the sign of the non-local conductance is a measure for the charge distribution of the ABS, given by the respective Bogoliubov-de Gennes amplitudes $u$ and $v$.

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Jens Schindele, Andreas Baumgartner, Romain Maurand, Markus Weiss, Christian Schönenberger. 2013-11-04. Non-local spectroscopy of Andreev bound states. https://doi.org/10.1103/physrevb.89.045422

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