General description: The main goal of the project is to model and investigate theoretically the potential of spin-photon interfaces for quantum information processing. Such devices consist of single spins coupled to light propagating in waveguides, or photonic circuits : in these so-called "one dimensional atoms", light matter interaction is so strong that the spin state leaves a macroscopic imprint on single photons having interacted with it. The spin- photon interface opens major perspectives for quantum physics and quantum information processing, such as Quantum Non Demolition measurement of the spin using a single photon, or the possible engineering of spin-photon entanglement. On the other hand, one-dimensional devices have a range of promising functionalities when embedded in a network, e.g. could provide efficient quantum gates, quantum repeaters, or light rectifiers.

Detailed description and means: The project will build on recent experimental achievements obtained at LPN-Marcoussis with a single quantum dot spin embedded in a pillar cavity. The group has shown that when a single photon interacts with a spin, its polarization is macroscopically rotated, depending on the spin state (giant Faraday/Kerr rotation). We will set up a dedicated input-output formalism to model the spin-photon interface. Building on this description, we plan to investigate the backaction on the spin system induced by the measurement with light. The potential of this new platform for foundations of quantum theory (e.g. generation of Schrödinger cat states of light, or quantum thermodynamics) will also be addressed. This part of the project will benefit from a grant funding a starting collaboration between LPN and Néel (ANR "SPIQE", 2015-2018).

Interactions and collaborations :
The project will be conducted at the Institute Néel of Grenoble under the supervision of Alexia Auffèves, in close collaboration with the experimental teams of Loïc Lanco and Pascale Senellart at LPN-Marcoussis. More theoretical aspects of the work related to quantum information and photonic technologies will be investigated within a network involving the Federal University of Minas Gerais (Brazil) and the University of Pavia (Italy).

Expected profile :
The applicant should have good knowledges of quantum physics and quantum optics, and like working in close collaboration with experimentalists. Experience in coding will be appreciated.

Foreseen start for the grant : any time starting from June 2015
Amount : round 1400 euros per month netto
Duration : 36 months
Contact : Alexia Auffèves alexia.auffeves@neel.cnrs.fr