Generation and Detection of Mesoscopic Pulsed States of Light for Quantum Information

摘要: Generation and measurement of quantum states the electromagnetic field represent a hot widely discussed topic in Physics community, since optical are useful not only fundamental experiments but also several applications fields Quantum Optics Information (Bouwmeester et al., 2000). In fact, radiation is endowed with relevant characteristics as it travels at maximum possible speed, almost unaffected by interaction environment, which many cases represents an unavoidable decoherence source, can be integrated optoelectronic circuits to implement computing protocols (Sansoni 2010). The possibility using applicative depends on capability generating manipulating that robust respect losses (i.e. contain sizeable number photons) produced measured high rate. For all these reasons, mesoscopic pulsed containing few tens photons per pulse seem ideal candidates for communication each must addressed individually. Moreover, problem suitable considered together question their characterization. nowadays we have types pulsed-light sources our disposal, them characterized different durations (from fs up ns), pulse-repetition rates Hz 100 MHz) wide range energies nJ J). However, light easily measured. intensity regime, example, detectors photon-number resolution required so determine shot-by-shot photon numbers or, least, characterize some features states. full characterization state, obtained e.g. evaluating its Wigner function, achieved homodyne tomography (OHT) (Raymer, 1997), technique over years has proved effectiveness reconstructing both classical states, even if further optimizations needed case (Zavatta 2006). Direct detection schemes alternative OHT knowing statistics detected sufficient signal demonstrated pioneering work Arecchi (Arecchi, 1965). Obviously, implementation direct scheme requires proper choice detector, development calibration 11