Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
Tools for quantum information: work at INRIM on characterization of quantum optical states, communication channels, and photo-detectors
Nicolò Antonietti, G. Brida, Marco Genovese, Marco Gramegna, Leonid A. Krivitsky, Alice Meda, Fabrizio Piacentini, E. Predazzi, Ivano Ruo Berchera, P. Traina
In this paper we will present some of the work performed at INRIM on the application of quantum optical states to quantum information and metrology. In particular we will consider some specific tools needed for quantum information researches as the characterization of the quantum optical states, communication lines and detectors. In little more detail, after a general presentation of the activity of our lab, we will describe a series of experiments where we have reconstructed the statistics of various quantum optical states with an innovative method based on a "variable" quantum efficiency of detectors. The success of the presented applications and the simplicity of the method suggest a possible widespread applicability of it. We will then describe our work on photo-detectors calibration by exploiting PDC light and in particular the extension to analog detectors. Finally, we will mention some research in progress on the effects of the communication line (fiber, open air) on the transmitted quantum state.
In this paper we will present some of the work performed at INRIM on the application of quantum optical states to quantum information and metrology. In particular we will consider some specific tools needed for quantum information researches as the characterization of the quantum optical states, communication lines and detectors. In little more detail, after a general presentation of the activity of our lab, we will describe a series of experiments where we have reconstructed the statistics of various quantum optical states with an innovative method based on a "variable" quantum efficiency of detectors. The success of the presented applications and the simplicity of the method suggest a possible widespread applicability of it. We will then describe our work on photo-detectors calibration by exploiting PDC light and in particular the extension to analog detectors. Finally, we will mention some research in progress on the effects of the communication line (fiber, open air) on the transmitted quantum state.
In this paper we will present some experimental researches about Quantum Communication performed in "Carlo Novero" Quantum Optics laboratory at INRiM (former IEN). After a general review of our studies, we will describe our recent researches on propagation of polarization entangled photons in optical fibres focused on the investigation of the effect of two-photon interference in the second-order Glauber's correlation function and on the characterization of this quantum channel as a Complete Positive (CP) map. We will then describe an innovative method, based on detectors operating in Geiger mode (on/off), for reconstructing the photon statistics of quantum optical states, presenting experimental data collected to test the extension of this method to multi-partite states.
ABSTRACT We review our last results in the field of quantum imaging obtained at INRIM Keywords: Quantum Imaging, Entanglement, Quantum Correlations, Sub shot noise measurements 1. INTRODUCTION Quantum properties of the optical field represent a resource of the utmost relevance for the development of quantum technologies, allowing unprecedented results in disciplines ranging from quantum information and metrology to quantum imaging. In particular, in the last case various protocols have been proposed ranging from ghost imaging [1,2], to quantum illumination [3] and sub-shot-noise quantum imaging [4]. Sub-shot-noise measurements with quantum optical states (for example exploiting the quantum correlations of Parametric Down Conversion (PDC) emission) provide the possibility of the detection of weak objects, a task that could have important practical applications. A little more in detail the principle of this technique is to take advantage of the correlation in the noise of two conjugated branches of PDC emission: in fact, s ubtracting the noise measured on one branch from the image of a weak object obtained in the other branch, the image of the object, previously hidden in the noise, could be restored. A schematic implemen tation of this protocol is depicted in Figure 1. On the other hand, ghost imaging technique allows to retrieve information about the object using spatial resolution detector from light (one arm of correlated beams) that does not interact directly with the object, whereas the photons transmitted thr ough (or reflected by) the object are registered by a bucket detector, which does not resolve the shape of the object.
Non-classical light is both easily encoded with quantum information and robust against decoherence, making it a key resource that enables many quantum information applications including quantum computing, quantum communication, and quantum metrology. We present a wide range of experimental and theoretical research toward the generation, detection, characterization, and storage of non-classical states of light with an eye toward quantum information applications. To provide a basis for the rest of the work, we begin by discussing theoretically the role of photon number statistics in optical quantum information and the use of second-order optical coherence to characterize non-classical light. Building on that, we present an original tool for the difficult problem of reconstructing the underlying mode distribution of multi-mode optical fields using simple measurements of higher-order optical coherence. We then move on to the problem of generating and storing single photons. We do this in a solid-state medium, a rare-earth ion-doped crystal, with a long-lived spin transition ideal for storing quantum information. We experimentally demonstrate the feasibility of this concept by showing correlations between the optical fields that herald storage and retrieval of collective excitations. This scheme can be used for the two important and distinct applications of generating single photons on-demand and storing quantum information and entanglement. The detection of non-classical light is a task as important as its generation. To this end, we study detectors with near unity detection efficiency and photon number resolution for use in quantum-enabled metrology. We use such a detector to experimentally demonstrate compression of spatial fringes and investigate the possibility of improving measurement resolution with classical and non-classical light. Finally, we report a set of experiments using photon number statistics to characterize classical and non-classical light. We measure suppression of unwanted multi-photon emission in a heralded single photon source based on four-wave mixing in microstructure optical fiber. And we, for the first time, experimentally demonstrate reconstruction of multi-mode classical and non-classical light from measured photon number statistics.
This paper's purpose is to review the results recently obtained in the Quantum Optics labs of the National Institute of Metrological Research (INRIM) in the field of single- and few-photon detectors calibration, from both the classical and quantum viewpoint. In the first part of the paper is presented the calibration of a single-photon detector with absolute methods, while in the second part we focus on photon-number-resolving detectors, discussing both the classical and quantum characterization of such devices.
The research activities described in this thesis have basically an experimental profile, and were realized in the Quantum Optics Laboratories of the Optic Division in the Istituto Nazionale di Ricerca Metrologica (I.N.Ri.M.). The experiments presented here are oriented to the characterization of single- and few-photon detectors calibration, exploiting quantum properties. The first chapter has an introductory character, oriented to the study of nonlinear optics phenomena and focused in the spontaneous parametric down conversion (PDC) process. After the quantization of the free electromagnetic field, we recall the quantum theory of PDC. In the second chapter the Klyshko's two-photon calibration technique is presented and applied to an Avalanche Photo Diode (APD) based single photon counting module. Chapter three is an introduction to quantum measurements and quantum operation theories where the concept of positive-operator valued measurement (POVM) is presented. In chapter four, the quantum characterization of a true photon-number resolving detector (PNRD) based on a transition edge sensor (TES) is presented. In this experiment, the POVM of the TES is reconstructed by realizing a tomography of the detection process's quantum operation, using as a probe a set of known coherent states. In the fifth and last chapter, the POVM of a tree type PNRD is reconstructed exploiting strong quantum correlations of PDC twin beams
We present some Quantum Tomography related results recently obtained in the Quantum Optics labs of the National Institute of Metrological Research (INRIM). Initially we describe the first experimental implementation of a new protocol for the reconstruction of a photon-number-resolving (PNR) detector’s POVM (Positive Operator-Valued Measure): such a protocol, exploiting the strong quantum correlations of an ancillary state, results more robust and efficient than its classical counterparts. The second part of the paper focuses on the quantum characterization of a transition-edge sensor (TES) based PNR detector, i.e. the experimental tomography of the POVM of a TES, with a method based on a quorum of coherent probes: we show the reconstruction of the POVM elements up to 11 detected photons and 100 incoming photons, demonstrating the linearity of such a device. Finally, we present a method for the experimental reconstruction of the modal structure of multimode optical fields exploiting a single measurement of higher-order photon number autocorrelation functions. We show our reconstructions of up to three different modes per optical state, demonstrating the excellent agreement with the theoretical predictions and the robustness of our method itself.