Friday, April 25, 2014

Seminar "Light-matter interactions on a chip - nanoscale quantum transport and circuit QED" by prof. Peter Samuelsson

OSA un SPIE Latvijas Universitātes studentu nodaļas sadarbībā ar Atomāro un nepārtrauktās vides fizikālo procesu pētīšanas, modelēšanas un matemātisko metožu pilnveidošanas skolu aicina apmeklēt semināru "Light-matter interactions on a chip - nanoscale quantum transport and circuit QED", kas notiks otrdien, 29. aprīlī, plkst. 17:00 Zeļļu ielā 8, F219 telpā. Seminārā uzstāsies prof. Peter Samuelsson no Lundas Universitātes. Seminārs notiks angļu valodā. Ierašanās no 16:45 - būs cepumi un tēja.

The interaction between light and matter is a central area of research in modern physics. A prominent example is the interaction between single atoms and light particles, photons, where ground-breaking experiments have shed new light on the mind-boggling aspects of quantum mechanics, such as coherent superpositions and entanglement. During the last decade, concepts from controlled atom-light interactions have been carried over to superconducting electronic circuits, where man-made, artificial atoms interact with microwave photons. Very recently, systems where the artificial atoms are replaced by nanometersized electrical conductors started to be explored experimentally. This raises two important and fundamental questions: what novel properties of light-matter interactions are manifested  in systems with individual microwave photons coupled to single conduction electrons, and how can they be investigated in an experiment? Here we adress this question theoretically and find coherent, coupled electron-photon quantum states and non-local electron correlations, accessible via the electrical current and its fluctuations.

We consider a system where the microwave photons are confined in a cavity formed by superconducting metal striplines. The nanoscale conductors consist of two double quantum dots, coupled to the fundamental mode of the cavity. The system constitutes a generalization of the Tavis-Cummings model, actively investigated in the context of atom-light interactions. Our transport formalism allows us to account for the coherent, non-equilibrium properties of the coupled electron-photon system. We find sizeable non-locally induced electrical currents as well as correlations between currents, mediated by individual microwave photons. Moreover, we show that electrons in different dots can be entangled by exchanging a single photon.

Our investigation forms the basis for further experimental and theoretical investigations on microwave-coupled electrons in nanoscale conductors. These intriguing systems put in prospect novel, fundamental aspects of light-matter interactions in the deep quantum regime as well as applications in e.g. quantum information processing and efficient heat transfer at the nanoscale.

Turpmākai lasīšanai:
C. Bergenfeldt, P. Samuelsson, Phys. Rev. B 87, 195427 (2013).
C. Bergenfeldt, P. Samuelsson, B. Sothmann, C. Flindt, M. Büttiker,  Phys. Rev. Lett. 112, 076803, (2014).
T. L. van den Berg, C. Bergenfeldt, P. Samuelsson, arXiv:1402.1351