Dynamical Coulomb Blockade in an avalanche diode at room temperature

Dynamical Coulomb Blockade refers to the transport properties of a conductor being affected by its electromagnetic environment. It is usually attributed to the discreteness of the charge carriers, observable at very low temperature and explained in terms of quantum mechanics. It can also be understood in terms of a feedback effect of the noise of the conductor on itself through an external impedance. While quantum noise may be involved in this process, it is not a key ingredient: all that is needed is to have a sample which exhibits voltage-dependent noise. Such classical Dynamical Coulomb Blockade should be observable with many devices even at room temperature. We have measured dc transport and noise of an avalanche diode in series with a resistor. By playing with the value of the external resistor, which controls the strength of the feedback, we demonstrate experimentally the existence of huge Dynamical Coulomb Blockade. We discuss a simple theoretical picture.