Ultrabright source of entangled photon pairs

Laboratoire de Photonique et de Nanostructures, CNRS, route de Nozay, 91460 Marcoussis, France.
Nature (Impact Factor: 42.35). 07/2010; 466(7303):217-20. DOI: 10.1038/nature09148
Source: PubMed

ABSTRACT A source of triggered entangled photon pairs is a key component in quantum information science; it is needed to implement functions such as linear quantum computation, entanglement swapping and quantum teleportation. Generation of polarization entangled photon pairs can be obtained through parametric conversion in nonlinear optical media or by making use of the radiative decay of two electron-hole pairs trapped in a semiconductor quantum dot. Today, these sources operate at a very low rate, below 0.01 photon pairs per excitation pulse, which strongly limits their applications. For systems based on parametric conversion, this low rate is intrinsically due to the Poissonian statistics of the source. Conversely, a quantum dot can emit a single pair of entangled photons with a probability near unity but suffers from a naturally very low extraction efficiency. Here we show that this drawback can be overcome by coupling an optical cavity in the form of a 'photonic molecule' to a single quantum dot. Two coupled identical pillars-the photonic molecule-were etched in a semiconductor planar microcavity, using an optical lithography method that ensures a deterministic coupling to the biexciton and exciton energy states of a pre-selected quantum dot. The Purcell effect ensures that most entangled photon pairs are emitted into two cavity modes, while improving the indistinguishability of the two optical recombination paths. A polarization entangled photon pair rate of 0.12 per excitation pulse (with a concurrence of 0.34) is collected in the first lens. Our results open the way towards the fabrication of solid state triggered sources of entangled photon pairs, with an overall (creation and collection) efficiency of 80%.

1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Arrays of photonic cavities are relevant structures for developing large-scale photonic integrated circuits and for investigating basic quantum electrodynamics phenomena, due to the effective photon hopping between interacting nanoresonators. Here, we investigate, by means of scanning near-field spectroscopy and numerical calculations, the role of different neighboring interactions that give rise to delocalized supermodes in different photonic crystal array configurations. The systems under investigation consist of three nominally identical two-dimensional photonic crystal nanocavities on membrane aligned along the two symmetry axes of the triangular photonic crystal lattice. We find that the nearest and next-nearest-neighbour coupling terms can be of the same relevance. In this case, a non-intuitive picture describes the resonant modes, and the photon hopping between adjacent nano-resonators is strongly affected. Our findings prove that exotic configurations and even post-fabrication engineering of coupled nanoresonators could directly tailor the mode spatial distribution and the group velocity in in coupled resonator optical waveguides.
    04/2015; DOI:10.1021/acsphotonics.5b00041
  • [Show abstract] [Hide abstract]
    ABSTRACT: Distributed Bragg reflector based semiconductor resonators constitute paradigmatic systems where cavity optomechanical and optoelectronic phenomena can be simultaneously active in the same device. High GHz range mechanical frequencies and ultrastrong optomechanical couplings are additional attractive features for applications. We report here a detailed spectroscopic study of the fundamental optomechanical resonances of such a device. The existent challenge to study vibrational frequencies that are above the bandwidth of current electronics is solved using a purposely made tandem Fabry-Pérot-triple spectrometer. A full theoretical description of the Raman process including electronic, vibrational, and optical confinement is presented to describe the experiments. These results open the path for the demonstration of polariton optomechanical phenomena in these devices.
    Physical Review B 07/2014; 90(4):045314. DOI:10.1103/PhysRevB.90.045314 · 3.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Open-access microcavities are emerging as a new approach to confine and engineer light down to the {\lambda}^3 regime. Indeed, they offer direct access to a highly confined electromagnetic field while maintaining tunability of the system and flexibility on the light emitter studied. In this article, we present the first development beyond the single open-access cavity design using a Focused Ion Beam fabrication method. Based on experimental and theoretical investigation, we demonstrate the engineering of the coupling between two open-access microcavities with radius of curvature of 6 {\mu}m. We study the evolution of spectral, spatial and polarisation properties through a transition from isolated to coupled cavities. Normal mode splittings up to 20 meV are observed for total mode volumes around 10 {\lambda}^3 . This work is of importance for future development of photonic circuits for quantum computation, optical meta-materials and lab-on-a-chip sensing.


Available from
May 27, 2014