DIPC Colloquium: Cooper-pairs are nice, but split ones too!
DIPC Seminars
- Speaker
-
Christian Schönenberger, Department of Physics, University of Basel, and Swiss Nanoscience Institute, Switzerland
- When
-
2018/06/14
19:30 - Place
- Donostia International Physics Center
- Add to calendar
- iCal
An elegant concept for the creation of entangled electrons in a solid-state
device is to split Cooper pairs by coupling a superconductor to two parallel
quantum dots (QDs) in a Y-junction geometry [1]. Cooper pair splitting (CPS)
was investigated in recent years in devices based on InAs nanowires [2,3] and
carbon nanotubes (CNTs) [4,5] and identified by a positive correlation between
the currents through the QDs. I will first review these experiments and
demonstrate that high splitting efficiencies >90% can be achieved [5]. A high
CPS efficiency is a prerequisite for Bell state measurements [6], a clear way
of proving that Cooper pairs can be extracted coherently, leading to spatially
separated entangled electron pairs. Further requirements on entanglement
measurements will be addressed in the talk as well [6] and a future
perspective will be given.
My aim is to give a historical view of research that started around 10 years
ago in my lab, hopefully understandable a general audience interested in
solid-state physics in general. This journey shows how scientific research
evolves, where one often takes detours and where one constantly has to reflect
the finding in the lab based on either physical intuition (simple minded
models) or, if available, good theory.
This is a collaborative effort with many people, see my group website
[www.nanoelectronics.ch](http://www.nanoelectronics.ch) and other goups as
well. I would like to mention in particular the groups of Szabolcs Csonka,
Budapst University of Technology and Economy, Jesper Nygard, Nano-Science
Center, Niels Bohr Institute of the University of Copenhagen, and Jan
Martinek- IFM-PAN, Poznan, Polen. I acknowledge funding from the Swiss NFS,
SNI, NCCR-QSIT, FP7-SE2ND and ERC-QUEST.
[1] P. Recher, E.V. Sukhorukov and D. Loss, Phys. Rev. B 63, 165314 (2001).
[2] L. Hofstetter, S. Csonka, J. Nygård and C. Schönenberger, Nature 461,
960 (2009).
[3] L. Hofstetter, S. Csonka, A. Baumgartner, G. Fülöp S. d'Hollosy, J.
Nygård and C. Schönenberger, Phys. Rev. Lett. 107, 136801 (2011).
[4] L.G. Herrmann, F. Portier, P. Roche, A. Levy Yeyati, T. Kontos and C.
Strunk, Phys. Rev. Lett. 104, 026801 (2010).
[5] J. Schindele, A. Baumgartner, and C. Schönenberger, Phys. Rev. Lett. 109,
157002 (2012).
[6] W. Kłobus, A. Grudka, A. Baumgartner, D. Tomaszewski, C. Schönenberger,
and J. Martinek, Phys. Rev. B 89, 125404 (2014).
[7] G. Fülöp, S. d'Hollosy, A. Baumgartner, P. Makk, V. A. Guzenko, M. H.
Madsen, J. Nygård, C. Schönenberger, and S. Csonka, Phys. Rev. B 90, 235412
(2014).
[8] J. Schindele, A. Baumgartner, R. Maurand, M. Weiss, and C. Schönenberger,
Phys. Rev. B 89, 045422 (2014).