Coulomb Blockade & Quantum Dot

Single-electron tunneling in a quantum dot. The Coulomb blockade arises because adding one electron costs charging energy E_c = e²/2C. Periodic conductance peaks appear as the gate voltage aligns charge states. The stability diagram shows Coulomb diamonds in the V_g-V_bias plane.

Parameters

Coulomb blockade:
Charging energy: E_c = e²/2C
N→N+1 transition at: e·V_g = (N+½)·e²/C
Diamond half-width: e·V_bias = ±E_c

Quantum vs. classical:
When Δε > kT: discrete energy levels visible (quantum dot)
When Δε < kT: quasi-continuous (classical dot)

Peaks: Conductance peaks occur when two charge states are degenerate. Peak spacing = e/C_g (in gate voltage).