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We present a theoretical analysis of the process of spontaneous parametric down conversion (SPDC) in a non-linear crystal characterized by a linearly-chirped X(2) grating along the direction of propagation. Our analysis leads to an…

Quantum Physics · Physics 2016-08-08 X. Sanchez-Lozano , Jose Luis Lucio

We present theoretical and experimental study of preparing maximally entangled two-photon polarization states, or Bell states, using femtosecond pulse pumped spontaneous parametric down-conversion (SPDC). First, we show how the inherent…

Quantum Physics · Physics 2009-11-07 Yoon-Ho Kim , Maria V. Chekhova , Sergei P. Kulik , Morton H. Rubin , Yanhua Shih

Quantum photonic technologies rely on the ability to generate, manipulate, and interfere indistinguishable single photons on a scalable platform. Among the various approaches, spontaneous parametric down-conversion (SPDC) remains one of the…

Quantum Physics · Physics 2026-03-03 Jost Kellner , Alessandra Sabatti , Tristan Kuttner , Robert J. Chapman , Rachel Grange

We present comprehensive measurement data on the pump and collection beam parameters necessary to achieve high collection efficiency ($89.0 \pm 1.7 \%$) together with high brightness when a single $\beta$-Barium Borate crystal is operated…

Optics · Physics 2015-11-16 Brigitta Septriani , James A. Grieve , Kadir Durak , Alexander Ling

We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the…

Quantum Physics · Physics 2010-07-20 Hugo Cable , Gabriel A. Durkin

Tailoring spectral properties of photon pairs is of great importance for optical quantum information and measurement applications. High-resolution spectral measurement is a key technique for engineering spectral properties of photons,…

Optical downconversion is widely used for generating photon pairs, squeezed and entangled states of light, making it an indispensable tool in quantum optics and quantum information. In the regime where the pump is much stronger than the…

Quantum Physics · Physics 2025-10-14 D. B. Horoshko , V. S. Shchesnovich

For advanced quantum information technology, sources of photon pairs in quantum mechanically factorable states are of great importance for realizing high-fidelity photon-photon quantum gate operations. Here we experimentally demonstrate a…

This paper presents a detailed numerical study of the effect of focusing on the conversion efficiency of low-loss singly-resonant parametric oscillators with collinear focusing of pump and signal. Results are given for the maximal pump…

Optics · Physics 2009-10-31 Kai Druhl

The generation of entangled photons through Spontaneous Parametric Down-Conversion (SPDC) is a critical resource for many key experiments and technologies in the domain of quantum optics. Historically, SPDC was limited to the generation of…

We implement experimentally a method to generate photon-number$-$path and polarization entangled photon pairs using ``beamlike'' type-II spontaneous parametric down-conversion (SPDC), in which the signal-idler photon pairs are emitted as…

Quantum Physics · Physics 2009-11-10 Yoon-Ho Kim

We propose a novel, physically-constrained and differentiable approach for the generation of D-dimensional qudit states via spontaneous parametric down-conversion (SPDC) in quantum optics. We circumvent any limitations imposed by the…

A promising result from optical quantum metrology is the ability to achieve sub-shot-noise performance in transmission or absorption measurements. This is due to the significantly lower uncertainty in light intensity of quantum beams with…

Quantum Physics · Physics 2021-09-01 Agustina G. Magnoni , Laura T. Knoll , Miguel A. Larotonda

Photonic quantum technologies rely on the efficient generation and interference of indistinguishable photons. Exceptional achievements in this respect have been obtained by domain engineering of quasi-phase-matched parametric…

Spontaneous parametric down-conversion (SPDC) has shown great promise in the generation of pure and indistinguishable single photons. Photon pairs produced in bulk crystals are highly correlated in terms of transverse space and frequency.…

Quantum Physics · Physics 2023-08-21 Baghdasar Baghdasaryan , Fabian Steinlechner , Stephan Fritzsche

Entangled photon sources (EPS), the major building block for a variety of quantum communication protocols, are commonly developed by utilizing the spontaneous parametric down-conversion (SPDC) in $\chi^{2}$ nonlinear bulk optical materials.…

Quantum Physics · Physics 2022-07-14 Sandeep Singh , Vimlesh Kumar , Anirban Ghosh , G. K. Samanata

We investigate quantum sensing for spectroscopy in a system consisting of a two-level atom coupled to a continuum of modes. We focus on optimizing the pulse shape of a coherent state to maximize the quantum Fisher information (QFI) of the…

Quantum Physics · Physics 2025-09-15 Karthik Chinni , Nicolás Quesada

We present a theory of an interference process that starts with N coherently pumped two-mode parametric down-conversion (PDC) sources, whose output modes are directed to N observers such that each observer receives modes from two different…

Quantum Physics · Physics 2026-05-21 Marek Żukowski , Paweł Cieśliński , Marcin Markiewicz , Konrad Schlichtholz

In this report the decoherence sources for entangled photons created by spontaneous parametric down conversion phenomenon is studied. The phase and spatial distinguishability of photon pairs from orthogonal crystals reduce the maximum…

Quantum Physics · Physics 2020-07-15 Kadir Durak

Spontaneous parametric down-conversion (SPDC) is the most widely-used source of high-dimensional entangled two-photon states, and the entanglement in the spatial degree of freedom is considered best suited for harnessing high-dimensional…

Quantum Physics · Physics 2026-05-19 Radhika Prasad , Nilakshi Senapati , Abhinandan Bhattacharjee , Suman Karan , Anand K. Jha