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Magnetic Field Tuning and Quantum Interference in a Cooper Pair Splitter
G Fülöp1, F Domínguez2, S d'Hollosy3
1Department of Physics, Budapest University of Technology and Economics, and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki út 8, 1111 Budapest, Hungary.
Physical Review Letters
|December 10, 2015
Summary
Cooper pair splitting (CPS) uses quantum dots to separate electron pairs from superconductors. An external magnetic field tunes the conductance correlations, optimizing CPS device performance and demonstrating coherent electron propagation.
Area of Science:
- Condensed Matter Physics
- Quantum Information Science
Background:
- Cooper pair splitting (CPS) is a fundamental quantum mechanical process.
- CPS utilizes quantum dots to spatially separate entangled electrons from a superconductor.
Purpose of the Study:
- Investigate the evolution of conductance correlations in an InAs CPS device under an external magnetic field.
- Understand the role of local and nonlocal transport processes in shaping the observed signals.
Main Methods:
- Experimental measurements of gate dependence of conductance correlations in an InAs CPS device.
- Theoretical modeling using a three-site model to interpret experimental observations.
Main Results:
- Observed continuous evolution of the signal from asymmetric Lorentzian to Fano-type resonance with increasing magnetic field.
- Demonstrated that nonlocal CPS yields symmetric line shapes, while local transport exhibits asymmetry due to quantum interference.
- Showcased coherent propagation of electrons after emission from the superconductor.
Conclusions:
- External magnetic fields can effectively tune and optimize the performance of CPS devices.
- The study provides insights into the coherent nature of electron transport post-CPS.
- Experimental efficiency estimates represent a lower bound of the actual CPS efficiency.
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