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Quantum Dots: Past, Present, and Open Questions

Explore the history, current developments, and unresolved queries in the field of quantum dots, small artificial devices that exhibit quantization of energy levels and electron charge. Discover their potential applications in quantum computing and their role in understanding mesoscopic and strongly correlated systems.

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Quantum Dots: Past, Present, and Open Questions

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  1. Quantum Dots – Past, Present and Open Questions Yigal Meir Department of Physics & The Ilse Katz Center for Meso- and Nano-scale Science and Technology Beer Sheva, ISRAEL

  2. Quantum dot – an artificial device, small enough so that quantization of energy levels and electron charge are important

  3. Single molecules vertical quantum dots

  4. Tarucha et al.

  5. Vg mR mL Transmission resonance when

  6. Example: 2d harmonic oscillator

  7. Coulomb Blockade charging of a capacitor

  8. Coulomb blockade peaks Single electron transistor Kastner et al.

  9. Now include quantum effects: • energies • wavefunctions • The peak amplitude depends on the wavefunction the electron tunnels into

  10. Example - Quantum Hall effect: • All states within a landau level are degenerate, except edge states, En=(n+1/2)hwc • The radii are quantized pr2=nf0 (n – Landau level index) n=1 n=0

  11. McEuen et al.

  12. Spin flips Kouwenhoven et al.

  13. Level statistics and random matrix theory

  14. Dynamics Artificial molecules

  15. Nonlinear transport mL mR Probes the excited states

  16. Foxman et al.

  17. Correlation between excited state of N electrons and the ground states of N+1 electrons Marcus et al.

  18. B

  19. Yacoby, Heiblum Is transport through a quantum dot coherent ?

  20. Checking quantum measurement theory Aleiner, Wingreen, Meir

  21. Buks et al.

  22. The Kondo effect

  23. Relevant to transport through quantum dots Ng and Lee Glazman and Raikh

  24. Conductance (2e2/h) chemical potential

  25. Goldhaber-Gordon, Kastner (1998) Cronenwett et al. (1998)

  26. Kouwenhoven et al.

  27. Kondo scaling Temperature [K] Goldhaber-Gordon et al.

  28. The Kondo effect out of equilibrium Meir, Wingreen, Lee

  29. chang The two-impurity Anderson model Georges & Meir

  30. Kondo vs. RKKY Marcus et al.

  31. The two-channel Kondo effect Non- Fermi liquid ground state

  32. Oreg & Goldhaber-Gordon

  33. Phase of transmission amplitude Heiblum More open questions

  34. eV=DE Ensslin Inelastic process ?

  35. Noise measurements and electron bunching Heiblum

  36. Thomas et al. (1996,1998,2000) The “0.7 anomaly”

  37. Rejec and Meir

  38. conclusions • Quantum dots are controllable miniaturized devices, which can be instrumental in our understanding of mesoscopic and strongly correlated systems. • May be the basic ingredient in applications of quantum computing. • In spite of their apparent simplicity, still many open questions.

  39. Theory: Experiment:

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