Heat pump driven by the shot noise of a tunnel contact

• Double quantum dots excited by the noise of a quantum point contact.
• Asymmetry of the double dot may lead to directed current.
• Inhomogeneous Zeeman splitting separates spin-up and spin-down channel.
• Proper adjustment of energy levels tunes the electric current to zero.
• The net effect is cooling one lead without charging it.

We investigate a mechanism for cooling a lead based on a process that replaces hot electrons by cold ones. The central idea is that a double quantum dot with an inhomogeneous Zeeman splitting acts as energy filter for the transported electrons. The setup is such that hot electrons with spin up are removed, while cold electrons with spin down are added. The required non-equilibrium condition is provided by the capacitive coupling of one quantum dot to the shot noise of a strongly biased quantum point contact in the tunneling limit. Special attention is paid to the identification of an operating regime in which the net electrical current vanishes.