laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Séminaire, 3 Février 2014

Julien Basset (ETH Zurich)
Single-electron double quantum dot dipole-coupled to a single photonic mode

We have realized a hybrid solid-state quantum device [1] in which a single-electron semiconductor double quantum dot is dipole-coupled to a superconducting microwave frequency transmission line resonator. The dipolar interaction between the two entities manifests itself via dispersive and dissipative effects observed as frequency shifts and linewidth broadenings of the photonic mode respectively. A Jaynes-Cummings Hamiltonian master equation calculation is used to model the combined system response and allows for determining both the coherence properties of the double quantum dot and its interdot tunnel coupling with high accuracy [2]. Decoherence properties of the double dot are investigated as a function of the number of electrons inside the dots. They are found to be similar in the single-electron and many-electron regimes suggesting that the density of the confinement energy spectrum plays a minor role in the decoherence rate of the system under investigation [2]. Finally, while driven out-of-equilibrium with a simple voltage bias, the double quantum dot system emits photons into the resonator. We analyze the statistics of these emitted photons (degree of second order coherence) leaking out of the resonator into our detection chain. A surprising strong photon-bunching is observed that we tentatively relate to the electron statistics into the double dot.
[1] M. R. Delbecq et al., Phys. Rev. Lett. 107, 256804 (2011) ; T. Frey et al., Phys. Rev. Lett. 108, 046807 (2012) ; K. D. Petersson et al. Nature (London) 490, 380 (2012).
[2] J. Basset et al. Phys. Rev. B 88, 125312 (2013).