Special CPM Seminar

Josephson Photonics: The Bright Side of Inelastic Cooper Pair Tunnelling

Max Hofheinz

Laboratoire de Transport Electronique Quantique et Supraconductivité
Institut des Nanosciences et Cryogénie, CEA Grenoble

We have recently shown that a simple dc voltage-bias on a small Josephson junction leads to microwave emission via inelastic Cooper-pair tunneling [1]. In this process a tunneling Cooper pair emits one or several microwave photons with a total energy of 2eV. The observed average photon emission rate is well explained within the so-called P(E) theory, but this theory does not make any predictions about the statistics of the emitted photons. I will show experiments showing that the statistics of the emitted photons can be highly nontrivial, in agreement with recent theory [2-5]: Depending on the bias conditions and the impedance of the circuit in which the junction is embedded, we observe statistics ranging from super-bunched to strongly anti-bunched. This type of devices might therefore offer a new way of generating useful photon states for circuit quantum optics experiments, without the need of carefully calibrated control pulses.

[1] M. Hofheinz et al., PRL 106, 217005 (2011)
[2] C. Padurariu et al., PRB 86, 054514 (2012)
[3] V. Gramich et al., PRL 111, 247002 (2013)
[4] J. Leppäkangas et al., NJP 16, 015015 (2014)
[5] J. Leppäkangas et al., PRL 115, 027004 (2015)