1,720,975 research outputs found
Integrated sources and detectors of nonclassical states of light in silicon nitride
No full textThe work presented in this thesis aims to integrate sources and detectors of nonclassical states of light into a single photonic chip. Correlated pairs of single photons are among the most used sources in many quantum optics and quantum information experiments but their integration with detectors still remains a challenging task. In the first part of the thesis we exploit the generation of correlated pairs of photons in the visible spectrum using an integrated Silicon Nitride microring resonator. As the fabrication process of our sources is fully compatible with back-end CMOS technology, we also discuss the unique possibility of integration with silicon avalanche photodectors to provide a platform for commercially available, fully integrated, analogue quantum simulator working at room temperature. The drawback of universal quantum computation with single photons is its probabilistic nature that increases the technological complexity to obtain complete on chip integration of all necessary components to prepare, manipulate and measure quantum states of light. On the other hand, quantum information processing with continuous variables is completely deterministic. Therefore, in the second part of this work we report design, fabrication and experimental verification of an integrated source of broadband squeezed state of light on a photonic chip. We numerically investigate the amount of obtained squeezing and spurious noise that prevents us to observe shot noise reduction at short sideband frequencies. Additionally, we propose a design to extend our work towards hybridization with discrete variables to obtain qubits that can be protected against errors
Nanophotonic source of quadrature squeezing via self phase modulation
No full textSqueezed light is optical beams with variance below the shot noise level. They are a key resource for quantum technologies based on photons, and they can be used to achieve better precision measurements and improve security in quantum key distribution channels and as a fundamental resource for quantum computation. Here, we demonstrate an integrated source of squeezing based on four-wave mixing that requires a single laser pump, measuring 0.45 dB of broadband quadrature squeezing at high frequencies. We identify and verify that the current results are limited by excess noise produced in the chip and propose ways to reduce it. Calculations suggest that an improvement in the optical properties of the chip achievable with existing technology can develop scalable quantum technologies based on ligh
Dataset for “High-Q/V photonic crystal cavities and QED analysis in 3C-SiC”
No full textDataset supports: Chatzopoulos, I., Martini, F., Cernansky, R., & Politi, A. (2019). High-Q/V photonic crystal cavities and QED analysis in 3C-SiC. ACS Photonics.</span
Complementary metal-oxide semiconductor compatible source of single photons at near-visible wavelengths
No full textWe demonstrate on-chip generation of correlated pairs of photons in the near-visible spectrum using a CMOS compatible plasma-enhanced chemical vapor deposition silicon nitride photonic device. Photons are generated via spontaneous four wave mixing enhanced by a ring resonator with high intrinsic quality Q-factor of 3,20,000, resulting in a generation rate of 950,000 pairs-mW. The high brightness of this source offers the opportunity to expand photonic quantum technologies over a broad wavelength range and provides a path to develop fully integrated quantum chips working at room temperature
Silicon carbide photonic platform based on suspended subwavelength waveguides
No full textSilicon carbide (SiC) displays a unique combination of optical and spin-related properties that make it interesting for photonics and quantum technologies. However, guiding light by total internal reflection can be difficult to achieve, especially when SiC is grown as thin films on higher index substrates, such as silicon. Fabricating suspended subwavelength waveguides requires a single lithography step and offers a solution to the confinement problem, while preserving the design flexibility required for a scalable and complete photonic platform. Here we present a design for such a platform, which can be used for both classical and quantum optics operation. We simulate basic optical components and analyze how to exploit the high nonlinearities of SiC and its defects.</p
High-Q/V photonic crystal cavities and QED analysis in 3C-SiC
No full textSolid state quantum emitters are among the most promising candidates for single photon generation in quantum technologies. However, they suffer from decoherence effects that limit their efficiency and indistinguishability. For instance, the radiation emitted in the zero phonon line (ZPL) of most color centers is on the order of a few percent (e.g., NV– centers in diamond, VSiVC in SiC), limiting the emission rate of single photons as well as the efficiency. At the same time, reliable interfacing with photons in an integrated manner still remains a challenge in both diamond and SiC technology. Here we develop photonic crystal cavities with Q factors in the order of 7100 in 3C SiC. We discuss how this high confinement cavity can significantly enhance the fraction of photons emitted in the ZPL and improve their characteristics. We study the requirements to place SiC color centers in the strong coupling condition and analyze the maximum attainable enhancement in the weak coupling regime. The robustness of the increased efficiency and improved indistinguishability can open the way to quantum technologies in the solid state
Amplitude-multiplexed readout of single photon detectors based on superconducting nanowires
No full textThe realization of large-scale photonic circuits for quantum optics experiments at telecom wavelengths requires an increasing number of integrated detectors. Superconducting nanowire single photon detectors (SNSPDs) can be easily integrated onchip, and they can efficiently detect the light propagating inside waveguides. The thermal budget of cryostats poses a limit on the maximum number of elements that can be integrated on the same chip due to the thermal impact of the readout electronics. In this paper, we propose and implement a novel amplitude-multiplexing scheme allowing the efficient reading of several SNSPDs with only one readout port, thus enabling the realization of photonic circuits with a large number of modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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