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Complete gate control of supercurrent in graphene p-n junctions
Jae-Hyun Choi1, Gil-Ho Lee, Sunghun Park
11] Department of Physics, Pohang University of Science and Technology, Pohang 790 784, Republic of Korea [2].
Nature Communications
|September 24, 2013
Summary
Researchers developed bipolar Josephson junctions in graphene, enabling supercurrent ON/OFF control for quantum devices. This breakthrough utilizes electrostatic gating and offers tuneable quantum tunneling, advancing superconducting electronics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Information Science
Background:
- Conventional graphene Josephson junctions fail to switch off supercurrent at the charge neutrality point, hindering superconducting quantum device development.
- Graphene's unique electronic properties offer potential for novel superconducting devices, but control over supercurrent flow remains a challenge.
Purpose of the Study:
- To engineer graphene bipolar Josephson junctions capable of achieving controllable supercurrent ON/OFF states.
- To investigate gate-tuneable macroscopic quantum tunneling phenomena in these novel graphene structures.
- To elucidate the mechanism responsible for the supercurrent suppression in graphene Josephson junctions.
Main Methods:
- Fabrication of bipolar Josephson junctions in graphene using two superconducting contacts.
- Utilizing electrostatic gating to form a p-n potential barrier and control supercurrent.
- Characterization of supercurrent states and macroscopic quantum tunneling behavior.
- Analysis of the supercurrent suppression mechanism, including the role of pseudomagnetic fields.
Main Results:
- Demonstrated realization of fully gate-controlled supercurrent ON/OFF states in graphene bipolar Josephson junctions.
- Observed gate-tuneable macroscopic quantum tunneling of Josephson phase particles.
- Identified supercurrent dephasing induced by random pseudomagnetic fields from graphene ripples as the primary suppression mechanism.
Conclusions:
- Bipolar Josephson junctions in graphene provide a viable platform for achieving gate-tuneable supercurrent control.
- The findings offer a new pathway for developing advanced superconducting quantum information devices based on graphene.
- Understanding the dephasing mechanism is crucial for optimizing future graphene-based superconducting electronics.
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