  An electron-cooling principle based on Landau quantization is proposed for
nanoscale conductor systems. Operation relies on energy-selective electron
tunneling into a two-dimensional electron gas in quantizing magnetic fields.
This quantum refrigerator provides significant cooling power (~1 nW at a few K
for realistic parameters) and offers a unique flexibility thanks to its
tunability via the magnetic-field intensity. The available performance is only
marginally affected by nonidealities such as disorder or imperfections in the
semiconductor. Methods for the implementation of this system and its
characterization are discussed.
