Ivan Favero

A Semiconductor Ridge Micro Cavity Generating Counter-Propagating Twin Photons

We demonstrate twin photon emission in a AlGaAs ridge microcavity at room temperature. The pump beam resonance leads to an important efficiency enhancement of the nonlinear process generating counter-propagating twin photons at 1.55 micron.

Quantum State Transfer and Teleportation Between Remote Mechanical Resonators

We introduce a cavity-optomechanical system where the temporal envelope of input/output pulses is controlled by an independent classical drive. We design protocols for quantum communication between distant mechanical resonators.

GaAs disks optomechanics

At the nanoscale, the optomechanical coupling increases thanks to a reduced optical/mechanical interaction volume and reduced mass of the mechanical oscillator [1,2]. In the context of nano-optomechanics, semiconductors like GaAs offer many assets. First their large refractive index allows confining optical energy in sub-wavelentgh sized high-Q cavities. Second, nanoscale mechanical oscillators are easily coupled to such on-chip cavities using top-down fabrication techniques.

Semiconductor Ridge Microcavities Generating Counterpropagating Entangled Photons

In the last 25 years entangled photon pairs have been used first to test the foundations of quantum mechanics and then as building blocks in quantum information protocols : from the demonstration of the violation of Bell inequalities (Aspect et al., 1982; Tittel et al., 1998; Weihs et al., 1998) to the recent experiments in the domain of quantum-key distribution (Gisin et al., 2002), quantum computing (Deutch & Ekert, 1998; Wahther et al., 2005), teleportation (Bouwmeester et al., 1997) and absolute metrology (Migdall, 1999; Sergienko & Jaeger, 2003). The first process used to produce entangled two-photon states have been atomic radiative cascades (Aspect et al., 1982) and parametric fluorescence in birefringent dielectric materials (Kwiat et al., 1985). In order to achieve a good source, high collection efficiency is a key element because it affects the number of available photon pairs per unit time, and also because the presence of single photons having lost their twin is a source of noise in the detection. In this context we can mention several demonstrations of twin-photon generation based on either parametric down-conversion in periodically poled dielectric waveguides (Tanzilli et al., 2001; Banaszek et al., 2001) or four-wave mixing in optical fibers (Wang et al., 2001; Rarity et al. 2005; Fan & Migdall, 2007). An attractive alternative is provided by semiconductor materials, which exhibit a huge potential in terms of integration of novel optoelectronic devices. The first semiconductor source of entangled photons was based on the bi-exciton cascade of a quantum dot (Stevenson et al., 2006). With respect to this technique, parametric generation in semiconductor waveguides allows room-temperature operation and a high directionality of the emission, which dramatically enhances the collection efficiency. Several phase-matching schemes have been demonstrated in these systems (Ducci et al., 2005): form birefringence, modal phase matching, counterpropagating phase matching. In particular, the last one has attracted a deal of attention because of its unusual flexibility in the control of the quantum properties of the emitted photons (Walton et al., 2003; Walton et al., 2004; Perina, 2008). Here we present a semiconductor ridge microcavity emitting counterpropagating entangled photons; in Section 2 we explain the working principle of this device giving the details of the phase matching scheme and the effects of the microcavity. Section 3 is devoted to the