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Quantum Dots

Quantum Dots. Arindam Ghosh. Physics research on quantum dots What are the active areas. Understand nanoscale transport Materials Self-assembly of nano -structures Paradigm shift in functional electronics?. Organization of large number of nanostructures – scalability

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Quantum Dots

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  1. Quantum Dots ArindamGhosh

  2. Physics research on quantum dotsWhat are the active areas • Understand nanoscale transport • Materials • Self-assembly of nano-structures • Paradigm shift in functional electronics? Organization of large number of nanostructures – scalability Utilize natural forces Organic, inorganic and biological systems Effect of quantum mechanics Confinement and Coulomb force Spin effects and intrinsic magnetism Disorder – error optimization and modeling New nanostructured materials for transistors: Beyond silicon? Nanowires for interconnects or active elements New dielectrics: high-k and low-k Single electron transistors Carbon for next generation? New architecture? Electronics with nanomachines? Ferromagnetic logic devices? Quantum computation

  3. Single electron transistors (SET) – Operation of atomic switches Quantum Dot Gate Particle in a small box ~ 10 – 100 nm Energy-levels are quantized DE ~ 1/L2 Quantum effects only when DE>>kT Source Drain VSD VSD Source Drain current -Vg current current VSD Source-drain voltage (VSD) Gate voltage (Vg)

  4. The top-down approach Materials Plus Plus Creates Plan/Information Tools Product

  5. The bottom-up approach Self-AssembledProduct Creates Plus Tools Materials with stored information

  6. New materials and protocols for SET High-mobility two-dimensional electron gas Nano-engineering with silicon Semiconductor nanoparticles and nanowires Carbon electronics with nanotubes and graphene Molecules and DNA

  7. Si atoms Aluminum Gallium Arsenide Gallium Arsenide The two-dimensional electron gas in semiconductor heterostructures 2D electrons Extremely versatile Expensive Incompatible to Silicon technology

  8. Carbon nanotubes

  9. The Carbon nanotube single electron transistor Source Drain Gate

  10. Single electron transistor with nanotube rope

  11. Structures of Quantum dot

  12. Transport in single quantum dots

  13. Constant interaction model

  14. Coulomb blockade oscillations

  15. The magic numbers The Fock-Darwin Spectrum

  16. Experiment

  17. Excitation spectrum

  18. Quantum dot in quantum computation Spin qubit in single quantum dot Charge qubit in double quantum dots Varying readout schemes

  19. Spin measurement in a quantum dot “Spin to charge” conversion Nature 2004

  20. The protocol (1) Empty, (2) inject and wait, (3) measure

  21. Measuring spin

  22. Experiment

  23. 2D Artificial Atoms

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