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Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures.
Kristen Kaasbjerg1, Antti-Pekka Jauho1
1Center for Nanostructured Graphene (CNG), Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Physical Review Letters
|May 28, 2016
Summary
We theoretically investigate Coulomb drag in coupled quantum dots. A novel master-equation approach reveals a mesoscopic drag mechanism driven by nonlocal cotunneling, with current direction depending on energy-dependent lead couplings, not just drive current.
Area of Science:
- Condensed Matter Physics
- Quantum Transport Phenomena
- Mesoscopic Physics
Background:
- Coulomb drag describes the influence of charge motion in one conductor on another nearby conductor due to Coulomb interactions.
- Capacitively coupled quantum dots (CQDs) offer a tunable platform to study fundamental quantum transport phenomena.
- Understanding drag mechanisms is crucial for developing novel electronic devices and sensors.
Purpose of the Study:
- To theoretically investigate Coulomb drag in capacitively coupled quantum dots (CQDs).
- To identify the underlying mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes.
- To establish the conditions and directionality of the drag current in terms of microscopic system parameters.
Main Methods:
- Development of a master-equation approach to model transport in CQDs.
- Inclusion of higher-order tunneling processes, specifically cotunneling.
- Incorporation of energy-dependent lead couplings into the theoretical model.
- Application of the theory to graphene-based CQD heterostructures.
Main Results:
- Identification of a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling.
- Establishment of conditions for a nonzero drag current.
- Demonstration that drag current direction is determined by an interplay of energy-dependent lead couplings, not solely the drive current.
- Theoretical predictions show consistency with recent experimental observations in CQD systems.
Conclusions:
- The developed master-equation approach accurately describes Coulomb drag in CQDs.
- Nonlocal multielectron cotunneling is a key mechanism for mesoscopic Coulomb drag.
- Energy-dependent lead couplings play a critical role in determining the drag current direction.
- The findings provide a theoretical framework for understanding and potentially controlling Coulomb drag in quantum dot systems.
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