arXiv subjects

Marco Lamperti

Publications and source records attributed to Marco Lamperti.

12 recordsLinked to original sources

arXiv2026

Evaluating the performance of a weak-field homodyne receiver in quadrature phase-shift keying optical communication

Quantum communication protocols require efficient detection schemes to maximize the information transfer rate between the sender and the receiver. To this aim, we have demonstrated that weak-field receivers, merging wave-like and particle-like features, can be considered as a valid alternative to already existing receivers, such as optical homodyne detection. To better emphasize the potential of our receiver, in this work we consider a proof of concept for quaternary communication based on coherent states with the same amplitude and different phase values. The encoding in phase requires a fine control of phase noise obtained through a feedback system. The results achieved in terms of mutual information and secret key generation rate encourage further increase of the alphabet towards an approximately continuous phase modulation.

quant-ph↗

arXiv2025

Sum-frequency-based photon-number-resolving detector for telecom wavelengths

The use of C-band wavelengths in the field of quantum communication has grown significantly, driving the need for versatile detection solutions, especially in the low intensity domain. Among the desirable features for such detectors, photon-number-resolving (PNR) capability is particularly valuable, since it can offer new possibilities for enhancing security of communication protocols. In this paper, we present the implementation of a receiver that combines low-cost PNR detectors with nonlinear optical interactions to achieve sensitivity at telecom wavelengths. Specifically, we use this receiver to characterize the Poissonian nature of a femtosecond source at 1.5 $\mu$m, produced via white light continuum generation followed by a single-stage amplification process. The obtained results encourage the exploitation of such a detector in more complex schemes.

quant-ph↗

arXiv2024

Assessing a binary quantum channel exploiting a Silicon photomultiplier based hybrid receiver

In quantum communication protocols, the use of photon-number-resolving detectors could open new perspectives by broadening the way to encode and decode information, and merging the properties of discrete and continuous variables. In this work, we consider a quantum channel exploiting a Silicon-photomultiplier-based receiver and evaluate its performance for quantum communication protocols under three possible configurations, defined by different post-processing of the detection outcomes. We investigate two scenarios: information transmission over the channel, quantified by the mutual information, and continuous-variable quantum key distribution. The preliminary results encourage further use of this detection scheme in extended networks.

quant-ph↗

arXiv2023

On the use of superthermal light for imaging applications

Ghost imaging and differential ghost imaging are well-known imaging techniques based on the use of both classical and quantum correlated states of light. Since the existence of correlations has been shown to be the main resource to implement ghost imaging and differential ghost-imaging protocols, here we analyze the advantages and disadvantages of using two different kinds of superthermal states of light, which are more correlated than the typically employed thermal states. To make a fair comparison, we calculate the contrast (C) and the signal-to-noise ratio (SNR) of the reconstruct image. While the larger values of C suggest the usefulness of these superthermal states, the values of SNR do not improve by increasing the intensity fluctuations of light. On the contrary, they are the same as those exhibited by thermal light.

quant-ph↗

arXiv2022

High-Resolution Spectroscopy in the 11.6-15 μm Range by a Quasi-cw Difference-Frequency-Generation Laser Source

We report an approach for high-resolution spectroscopy using a widely tunable laser emitting in the molecular fingerprint region. The laser is based on difference-frequency generation (DFG) in a nonlinear orientation-patterned GaAs crystal. The signal laser, a CO2 gas laser, is operated in a kHz-pulsed mode while the pump laser, an external-cavity quantum cascade laser, is finely mode-hop-free tuned. The idler radiation covers a spectral range of 11.6 - 15 μm with a laser linewidth of 2.3 MHz. We showcase the versatility and the potential for molecular fingerprinting of the developed DFG laser source by resolving the absorption features of a mixture of several species in the long-wavelength mid-infrared. Furthermore, exploiting the wide tunability and resolution of the spectrometer, we resolve the broadband absorption spectrum of ethylene (C2H4) over 13 - 14.2 μm and quantify the self-broadening coefficients of some selected spectral lines.

physics.optics↗

arXiv2018

Collective dynamics of evanescently coupled excitable lasers with saturable absorber

We present a numerical study of the collective dynamics in a population of coupled excitable lasers with saturable absorber. At variance with previous studies where real-valued (lossy) coupling was considered, we focus here on the purely imaginary coupling (evanescent wave coupling). We show that evanescently coupled excitable lasers synchronize in a more efficient way compared to the lossy coupled ones. Furthermore we show that out-of-diagonal disorder-induced localization of excitability takes place for imaginary coupling too, but it can be frustrated by nonvanishing linewidth enhancement factor.

physics.optics↗

arXiv2017

Absolute spectroscopy near 7.8 μm with a comb-locked extended-cavity quantum-cascade-laser

We report the first experimental demonstration of frequency-locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locking scheme is applied to carry out absolute spectroscopy of N2O lines near 7.87 μm with an accuracy of ~60 kHz. Thanks to a single mode operation over more than 100 cm^{-1}, the comb-locked EC-QCL shows great potential for the accurate retrieval of line center frequencies in a spectral region that is currently outside the reach of broadly tunable cw sources, either based on difference frequency generation or optical parametric oscillation. The approach described here can be straightforwardly extended up to 12 μm, which is the current wavelength limit for commercial cw EC-QCLs.

physics.ins-det↗

arXiv2014

Luminescence-induced noise in single photon sources based on BBO crystals

Single-photon sources based on the process of spontaneous parametric down-conversion play a key role in various applied disciplines of quantum optics. We characterize intrinsic luminescence of BBO crystals as a source of non-removable noise in quantum-optics experiments. By analysing its spectral and temporal properties together with its intensity, we evaluate the impact of luminescence on single-photon state preparation using spontaneous parametric down-conversion.

quant-ph↗

arXiv2014

Spatial properties of twin-beam correlations at low- to high-intensity transition

It is shown that spatial correlation functions measured for correlated photon pairs at the single-photon level correspond to speckle patterns visible at high intensities. This correspondence is observed for the first time in one experimental setup by using different acquisition modes of an intensified CCD camera in low and high intensity regimes. The behavior of intensity auto- and cross-correlation functions in dependence on pump-beam parameters including power and transverse profile is investigated.

quant-ph↗

arXiv2013

Characterizing the non-classicality of mesoscopic optical twin-beam states

We present a robust tool to analyze nonclassical properties of multimode twin-beam states in the mesoscopic photon-number domain. The measurements are performed by direct detection. The analysis exploits three different non-classicality criteria for detected photons exhibiting complementary behavior in the explored intensity regime. Joint signal-idler photon-number distributions and quasi-distributions of integrated intensities are determined and compared with the corresponding distributions of detected photons. Experimental conditions optimal for nonclassical properties of twin-beam states are identified.

quant-ph↗

arXiv2013

Optimal sub-Poissonian light generation from twin beams by photon-number resolving detectors

We generate nonclassical conditional states by exploiting the quantum correlations of multi-mode twin-beam states endowed with a sizeable number of photons. A strong relation between the sub-shot-noise correlations exhibited by twin beams and the sub-Poissonian character of the conditional states is experimentally revealed. It determines optimal conditions for sub-Poissonian light generation.

quant-ph↗

arXiv2012

Optical black hole lasers

Using numerical simulations we show how to realise an optical black hole laser, i.e. an amplifier formed by travelling refractive index perturbations arranged so as to trap light between a white and a black hole horizon. The simulations highlight the main features of these lasers: the growth inside the cavity of positive and negative frequency modes accompanied by a weaker emission of modes that occurs in periodic bursts corresponding to the cavity round trips of the trapped modes. We then highlight a new regime in which the trapped mode spectra broaden until the zero-frequency points on the dispersion curve are reached. Amplification at the horizon is highest for zero-frequencies, therefore leading to a strong modification of the structure of the trapped light. For sufficiently long propagation times, lasing ensues only at the zero-frequency modes.

physics.optics↗