Quantum Dot Coulomb Staircase

Charging energy E_C 4.0 meV Level spacing Δ 1.5 meV Temperature kT 0.10 meV Gate voltage V_g 0.00 Bias sweep max V_b 20 meV

Coulomb Blockade

A quantum dot acts as an artificial atom. Adding each electron costs charging energy E_C = e²/2C plus quantum level spacing Δ. At low T, current flows only when the bias overcomes this addition energy, producing a staircase in I–V and diamond-shaped blockade regions in (V_bias, V_gate) space.

Each diamond is a Coulomb blockade diamond where electron number N is fixed. Degeneracy points allow single-electron tunneling.