Efficient erasure of quantum information beyond Landauer's limit

Landauer's principle sets a fundamental limit on the heat dissipated when one classical bit of information is erased from a memory, therefore establishing a direct link between information theory and thermodynamics. However, with the advent of quantum technologies, the question of whether there is a strategy to overcome the principle naturally emerges. In this work, we present a quantum channel which erases any qubit state with unit probability, and is capable of operating beyond Landauer's limit. The method is based only on unitary operations, and requires that a non-energetic degree of freedom of the thermal reservoir be preselected into a pure state before interacting with the qubit memory. The violation of the Landauer bound is verified when the reservoir temperature is above a given limit temperature, which can be well below room temperature.