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Open AccessEditorial

Special Issue on Basics and Applications in Quantum Optics

by Alessia Allevi, Stefano Olivares and Maria Bondani

Appl. Sci. 2021, 11(21), 10028; https://doi.org/10.3390/app112110028 - 26 Oct 2021

Cited by 1 | Viewed by 1436

Abstract

Quantum technologies are advancing very rapidly and have the potential to innovate communication and computing far beyond current possibilities [...] Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

Research

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12 pages, 2205 KiB

Open AccessFeature PaperArticle

An Enhanced Photonic Quantum Finite Automaton

by Alessandro Candeloro, Carlo Mereghetti, Beatrice Palano, Simone Cialdi, Matteo G. A. Paris and Stefano Olivares

Appl. Sci. 2021, 11(18), 8768; https://doi.org/10.3390/app11188768 - 21 Sep 2021

Cited by 6 | Viewed by 2127

Abstract

In a recent paper we have described an optical implementation of a measure-once one-way quantum finite automaton recognizing a well-known family of unary periodic languages, accepting words not in the language with a given error probability. To process input words, the automaton exploits [...] Read more.

In a recent paper we have described an optical implementation of a measure-once one-way quantum finite automaton recognizing a well-known family of unary periodic languages, accepting words not in the language with a given error probability. To process input words, the automaton exploits the degree of polarization of single photons and, to reduce the acceptance error probability, a technique of confidence amplification using the photon counts is implemented. In this paper, we show that the performance of this automaton may be further improved by using strategies that suitably consider both the orthogonal output polarizations of the photon. In our analysis, we also take into account how detector dark counts may affect the performance of the automaton. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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18 pages, 1499 KiB

Open AccessFeature PaperArticle

Conditional Measurements with Silicon Photomultipliers

by Giovanni Chesi, Alessia Allevi and Maria Bondani

Appl. Sci. 2021, 11(10), 4579; https://doi.org/10.3390/app11104579 - 17 May 2021

Cited by 3 | Viewed by 1734

Abstract

Nonclassical states of light can be efficiently generated by performing conditional measurements. An experimental setup including Silicon Photomultipliers can currently be implemented for this purpose. However, these devices are affected by correlated noise, the optical cross talk in the first place. Here we [...] Read more.

Nonclassical states of light can be efficiently generated by performing conditional measurements. An experimental setup including Silicon Photomultipliers can currently be implemented for this purpose. However, these devices are affected by correlated noise, the optical cross talk in the first place. Here we explore the effects of cross talk on the conditional states by suitably expanding our existing model for conditional measurements with photon-number-resolving detectors. We assess the nonclassicality of the conditional states by evaluating the Fano factor and provide experimental evidence to support our results. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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14 pages, 2231 KiB

Open AccessArticle

Experimental Quantum Message Authentication with Single Qubit Unitary Operation

by Min-Sung Kang, Yong-Su Kim, Ji-Woong Choi, Hyung-Jin Yang and Sang-Wook Han

Appl. Sci. 2021, 11(6), 2653; https://doi.org/10.3390/app11062653 - 16 Mar 2021

Cited by 4 | Viewed by 2740

Abstract

We have developed a quantum message authentication protocol that provides authentication and integrity of an original message using single qubit unitary operations. Our protocol mainly consists of two parts: quantum encryption and a correspondence check. The quantum encryption part is implemented using linear [...] Read more.

We have developed a quantum message authentication protocol that provides authentication and integrity of an original message using single qubit unitary operations. Our protocol mainly consists of two parts: quantum encryption and a correspondence check. The quantum encryption part is implemented using linear combinations of wave plates, and the correspondence check is performed using Hong–Ou–Mandel interference. By analyzing the coincidence counts of the Hong–Ou–Mandel interference, we have successfully proven the proposed protocol experimentally, and also showed its robustness against an existential forgery. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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11 pages, 4154 KiB

Open AccessArticle

Tunability of the Nonlinear Interferometer Method for Anchoring Constructive Interference Patterns on the ITU-T Grid

by Kyungdeuk Park, Dongjin Lee and Heedeuk Shin

Appl. Sci. 2021, 11(4), 1429; https://doi.org/10.3390/app11041429 - 5 Feb 2021

Cited by 3 | Viewed by 1937

Abstract

Recently, a method of engineering the quantum states with a nonlinear interferometer was proposed to achieve precise state engineering for near-ideal single-mode operation and near-unity efficiency (L. Cui et al., Phys. Rev. A 102, 033718 (2020)), and the high-purity bi-photon states can be [...] Read more.

Recently, a method of engineering the quantum states with a nonlinear interferometer was proposed to achieve precise state engineering for near-ideal single-mode operation and near-unity efficiency (L. Cui et al., Phys. Rev. A 102, 033718 (2020)), and the high-purity bi-photon states can be created without degrading brightness and collection efficiency. Here, we study the coarse or fine tunability of the nonlinear interference method to match constructive interference patterns into a transmission window of standard 100-GHz DWDM channels. The joint spectral intensity spectrum is measured for various conditions of the nonlinear interference effects. We show that the method has coarse- and fine-tuning ability while maintaining its high spectral purity. We expect that our results expand the usefulness of the nonlinear interference method. The photon-pair generation engineered via this method will be an excellent practical source of the quantum information process. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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12 pages, 763 KiB

Open AccessFeature PaperArticle

Tailoring Asymmetric Lossy Channels to Test the Robustness of Mesoscopic Quantum States of Light

by Alessia Allevi and Maria Bondani

Appl. Sci. 2020, 10(24), 9094; https://doi.org/10.3390/app10249094 - 19 Dec 2020

Cited by 8 | Viewed by 1772

Abstract

In the past twenty years many experiments have demonstrated that quantum states of light can be used for secure data transfer, despite the presence of many noise sources. In this paper we investigate, both theoretically and experimentally, the role played by a statistically-distributed [...] Read more.

In the past twenty years many experiments have demonstrated that quantum states of light can be used for secure data transfer, despite the presence of many noise sources. In this paper we investigate, both theoretically and experimentally, the role played by a statistically-distributed asymmetric amount of loss in the degradation of nonclassical photon-number correlations between the two parties of multimode twin-beam states in the mesoscopic intensity regime. To be as close as possible to realistic scenarios, we consider two different statistical distributions of such a loss, a Gaussian distribution and a log-normal one. The results achieved in the two cases show to what extent the involved parameters, both those connected to loss and those describing the employed states of light, preserve nonclassicality. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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21 pages, 3892 KiB

Open AccessArticle

Quantum Photonic Simulation of Spin-Magnetic Field Coupling and Atom-Optical Field Interaction

by Jesús Liñares, Xesús Prieto-Blanco, Gabriel M. Carral and María C. Nistal

Appl. Sci. 2020, 10(24), 8850; https://doi.org/10.3390/app10248850 - 10 Dec 2020

Cited by 3 | Viewed by 1856

Abstract

In this work, we present the physical simulation of the dynamical and topological properties of atom-field quantum interacting systems by means of integrated quantum photonic devices. In particular, we simulate mechanical systems used, for example, for quantum processing and requiring a very complex [...] Read more.

In this work, we present the physical simulation of the dynamical and topological properties of atom-field quantum interacting systems by means of integrated quantum photonic devices. In particular, we simulate mechanical systems used, for example, for quantum processing and requiring a very complex technology such as a spin-

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particle interacting with an external classical time-dependent magnetic field and a two-level atom under the action of an external classical time-dependent electric (optical) field (light-matter interaction). The photonic device consists of integrated optical waveguides supporting two collinear or codirectional modes, which are coupled by integrated optical gratings. We show that the single-photon quantum description of the dynamics of this photonic device is a quantum physical simulation of both aforementioned interacting systems. The two-mode photonic device with a single-photon quantum state represents the quantum system, and the optical grating corresponds to an external field. Likewise, we also present the generation of Aharonov–Anandan geometric phases within this photonic device, which also appear in the simulated systems. On the other hand, this photonic simulator can be regarded as a basic brick for constructing more complex photonic simulators. We present a few examples where optical gratings interacting with several collinear and/or codirectional modes are used in order to illustrate the new possibilities for quantum simulation. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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Review

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14 pages, 4277 KiB

Open AccessReview

Towards Quantum 3D Imaging Devices

by Cristoforo Abbattista, Leonardo Amoruso, Samuel Burri, Edoardo Charbon, Francesco Di Lena, Augusto Garuccio, Davide Giannella, Zdeněk Hradil, Michele Iacobellis, Gianlorenzo Massaro, Paul Mos, Libor Motka, Martin Paúr, Francesco V. Pepe, Michal Peterek, Isabella Petrelli, Jaroslav Řeháček, Francesca Santoro, Francesco Scattarella, Arin Ulku, Sergii Vasiukov, Michael Wayne, Claudio Bruschini, Milena D’Angelo, Maria Ieronymaki and Bohumil Stoklasa Show full author list Hide full author list

Appl. Sci. 2021, 11(14), 6414; https://doi.org/10.3390/app11146414 - 12 Jul 2021

Cited by 22 | Viewed by 3546

Abstract

We review the advancement of the research toward the design and implementation of quantum plenoptic cameras, radically novel 3D imaging devices that exploit both momentum–position entanglement and photon–number correlations to provide the typical refocusing and ultra-fast, scanning-free, 3D imaging capability of plenoptic devices, [...] Read more.

We review the advancement of the research toward the design and implementation of quantum plenoptic cameras, radically novel 3D imaging devices that exploit both momentum–position entanglement and photon–number correlations to provide the typical refocusing and ultra-fast, scanning-free, 3D imaging capability of plenoptic devices, along with dramatically enhanced performances, unattainable in standard plenoptic cameras: diffraction-limited resolution, large depth of focus, and ultra-low noise. To further increase the volumetric resolution beyond the Rayleigh diffraction limit, and achieve the quantum limit, we are also developing dedicated protocols based on quantum Fisher information. However, for the quantum advantages of the proposed devices to be effective and appealing to end-users, two main challenges need to be tackled. First, due to the large number of frames required for correlation measurements to provide an acceptable signal-to-noise ratio, quantum plenoptic imaging (QPI) would require, if implemented with commercially available high-resolution cameras, acquisition times ranging from tens of seconds to a few minutes. Second, the elaboration of this large amount of data, in order to retrieve 3D images or refocusing 2D images, requires high-performance and time-consuming computation. To address these challenges, we are developing high-resolution single-photon avalanche photodiode (SPAD) arrays and high-performance low-level programming of ultra-fast electronics, combined with compressive sensing and quantum tomography algorithms, with the aim to reduce both the acquisition and the elaboration time by two orders of magnitude. Routes toward exploitation of the QPI devices will also be discussed. Full article

(This article belongs to the Special Issue Basics and Applications in Quantum Optics)

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