Alessandro Ceré

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We demonstrate a way to prepare single photons with a temporal envelope that resembles the time reversal of photons from the spontaneous decay process. We use the photon pairs generated from a time-ordered cascade decay: the detection of the first photon of the cascade is used as a herald for the ground-state transition resonant second photon. We show how(More)
We demonstrate a light-shot-noise-limited magnetometer based on the Faraday effect in a hot unpolarized ensemble of rubidium atoms. By using off-resonant, polarization-squeezed probe light, we improve the sensitivity of the magnetometer by 3.2 dB. The technique could improve the sensitivity of the most advanced magnetometers and quantum nondemolition(More)
We demonstrate a high-brightness source of pairs of indistinguishable photons based on a type-II phase-matched doubly-resonant optical parametric oscillator operated far below threshold. The cavityenhanced down-conversion output of a PPKTP crystal is coupled into two single-mode fibers with a mode coupling efficiency of 58%. The high degree of(More)
We demonstrate the generation of rubidium-resonant heralded single photons for quantum memories. Photon pairs are created by cavity-enhanced down-conversion and narrowed in bandwidth to 7 MHz with a novel atom-based filter operating by "interaction-free measurement" principles. At least 94% of the heralded photons are atom-resonant as demonstrated by a(More)
We present an experimental test of the Clauser-Horne-Shimony-Holt Bell inequality on photon pairs in a maximally entangled state of polarization in which a value S=2.82759±0.00051 is observed. This value comes close to the Tsirelson bound of |S|≤2sqrt[2], with S-2sqrt[2]=0.00084±0.00051. It also violates the bound |S|≤2.82537 introduced by Grinbaum by 4.3(More)
We demonstrate a tunable narrowband filter based on optical-pumping-induced circular dichroism in rubidium vapor. The filter achieves a peak transmission of 14.6%, a linewidth of 80 MHz, and an out-of-band extinction of >or=35 dB. The transmission peak can be tuned within the range of the Doppler linewidth of the D1 line of atomic rubidium at 795 nm. While(More)
We investigate the scattering of single photons by single atoms and, in particular, the dependence of the atomic dynamics and the scattering probability on the photon bandwidth. We tightly focus the incident photons onto a single trapped <sup>87</sup>Rb atom and use the time-resolved transmission to characterize the interaction strength. Decreasing the(More)
Scattering of light by matter has been studied extensively in the past. Yet, the most fundamental process, the scattering of a single photon by a single atom, is largely unexplored. One prominent prediction of quantum optics is the deterministic absorption of a travelling photon by a single atom, provided the photon waveform matches spatially and temporally(More)
Sources of true randomness have numerous applications, be it in algorithms, gambling or cryptography [1]. However, their unpredictability is typically difficult to certify since they may be correlated to external variables, and access to those other variable could render their behavior predictable. Therefore, there is strong motivation for developing(More)
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