Coulomb blockade

Coulomb blockade is a phenomenon in tiny electronic devices where the movement of individual electrons is restricted due to their mutual electric repulsion. When a small conductor, like a quantum dot, is connected to electrodes through thin barriers, adding an extra electron requires a specific energy to overcome this repulsion. If the available energy isn't enough, electrons can't pass through, effectively "blocking" current flow. This results in a state where current only flows at certain voltages, leading to a characteristic "on-off" behavior useful in quantum electronics and sensitive detectors.