Marcus Huber

Autonomous Quantum Refrigerator in a Circuit-QED Architecture Based on a Josephson Junction

  1. Patrick P. Hofer,
  2. Martí Perarnau-Llobet,
  3. Jonatan Bohr Brask,
  4. Ralph Silva,
  5. Marcus Huber,
  6. and Nicolas Brunner
An implementation of a small quantum absorption refrigerator in a circuit QED architecture is proposed. The setup consists of three harmonic oscillators coupled to a Josephson unction.
The refrigerator is autonomous in the sense that it does not require any external control for cooling, but only thermal contact between the oscillators and heat baths at different temperatures. In addition, the setup features a built-in switch, which allows the cooling to be turned on and off. If timing control is available, this enables the possibility for coherence-enhanced cooling. Finally, we show that significant cooling can be achieved with experimentally realistic parameters and that our setup should be within reach of current technology.
arxiv pdf

Autonomous quantum thermal machine for generating steady-state entanglement

  1. Jonatan Bohr Brask,
  2. Nicolas Brunner,
  3. Géraldine Haack,
  4. and Marcus Huber
We discuss a simple quantum thermal machine for the generation of steady-state entanglement between two interacting qubits. The machine is autonomous in the sense that it uses only
incoherent interactions with thermal baths, but no source of coherence or external control. By weakly coupling the qubits to thermal baths at different temperatures, inducing a heat current through the system, steady-state entanglement is generated far from thermal equilibrium. Finally, we discuss two possible implementations, using superconducting flux qubits or a semiconductor double quantum dot. Experimental prospects for steady-state entanglement are promising in both systems.
arxiv pdf