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Spontaneous parametric down conversion (PDC), in the perturbative limit, can be considered as a probabilistic splitting of one input photon into two output photons. Conversely, sum-frequency generation (SFG) implements the reverse process…

Quantum Physics · Physics 2021-04-21 Sofiane Merkouche , Valérian Thiel , Brian J. Smith

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,…

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

In this paper, we are interested in detecting the presence of a nearby phase-sensitive object, where traveling light works out under a low-photon loss rate. Here we investigate the optimal quantum phase estimation with generalized…

Quantum Physics · Physics 2020-07-30 Seung-Woo Lee , Su-Yong Lee , Jaewan Kim

Cavity-enhanced Spontaneous parametric down-conversion (SPDC) is capable of efficient generation of single photons with suitable spectral properties for interfacing with the atoms. However, beside the remarkable progress of this technique,…

Quantum Physics · Physics 2019-10-29 Amir Moqanaki , Francesco Massa , Philip Walther

We propose a detection scheme for measuring the overlap of the quantum state of a weakly excited traveling-field mode with a desired reference quantum state, by successive mixing the signal mode with modes prepared in coherent states and…

Quantum Physics · Physics 2016-05-10 J. Clausen , M. Dakna , L. Knoll , D. -G. Welsch

In this paper, we propose an algorithm to construct coherent states for an exactly solvable position dependent mass Schr\"odinger equation. We use point canonical transformation method and obtain ground state eigenfunction of the position…

Quantum Physics · Physics 2010-03-16 V Chithiika Ruby , M Senthilvelan

We generate single-photon catalyzed coherent states (SPCCSs) by means of quantum-optical catalysis based on the beam splitter (BS) or the parametric amplifier (PA). These states are obtained in one of the BS (or PA) output channels if a…

Quantum Physics · Physics 2016-06-22 Xue-xiang Xu , Hong-chun Yuan

We propose a measure for the "size" of a Schroedinger cat state, i.e. a quantum superposition of two many-body states with (supposedly) macroscopically distinct properties, by counting how many single-particle operations are needed to map…

Quantum Physics · Physics 2008-07-22 Florian Marquardt , Benjamin Abel , Jan von Delft

Linear superpositions of macroscopically distinct quantum states (sometimes also called Schr\"odinger cat states) are usually almost immediately reduced to a statistical mixture if exposed to the dephasing influence of a dissipative…

Quantum Physics · Physics 2007-05-23 Daniel Braun , Petr A. Braun , Fritz Haake

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…

We outline a toolbox comprised of passive optical elements, single photon detection and superpositions of coherent states (Schrodinger cat states). Such a toolbox is a powerful collection of primitives for quantum information processing…

Quantum Physics · Physics 2009-11-10 A. Gilchrist , Kae Nemoto , W. J. Munro , T. C. Ralph , S. Glancy , Samuel. L. Braunstein , G. J. Milburn

We present a scheme, based only on linear optics and standard photon detection, that allows to generate heralded multiphoton entangled states of arbitrary photon number from spontaneous parametric downconversion (PDC) in the weak…

Quantum Physics · Physics 2008-04-16 Philip Walther , Markus Aspelmeyer , Anton Zeilinger

The nonlinear optical process of spontaneous parametric down-conversion (SPDC) is widely studied for applications in quantum information science due to its ability to produce two photons that can be entangled in many degrees of freedom. For…

Quantum Physics · Physics 2014-10-06 Hannah E. Guilbert , Daniel J. Gauthier

Photon modes have an important role in characterizing the quantum sources of light. Proper coupling of various photon modes obtained in spontaneous parametric down conversion (SPDC) process in optical fibers is essential to generate an…

Quantum Physics · Physics 2016-03-03 Ali Anwar , Chithrabhanu P , Salla Gangi Reddy , Nijil Lal , R. P. Singh

We propose an efficient quantum key distribution protocol based on the photon-pair generation from parametric down-conversion (PDC). It uses the same experimental setup as the conventional protocol, but a refined data analysis enables…

Quantum Physics · Physics 2009-11-13 Yoritoshi Adachi , Takashi Yamamoto , Masato Koashi , Nobuyuki Imoto

We develop a model for non-Gaussian state generation via spontaneous parametric down-conversion (SPDC) in InGaP microring resonators. The nonlinear Hamiltonian is written in terms of the asymptotic fields for the system, which includes a…

Quantum Physics · Physics 2025-10-09 Colin Vendromin , Samuel E. Fontaine , J. E. Sipe

Taking the decoherence into account, we investigate nonclassical features of the optical Schr\"odinger cat states in one mode and two coupled-modes systems with two-photon driving. In the one mode system, the relationship between the…

Quantum Physics · Physics 2017-07-19 X. L. Zhao , Z. C. Shi , M. Qin , X. X. Yi

An engineering technique using continuous quantum measurement together with a change detection algorithm is proposed to improve the probability of single photon emission for a quantum-dot based single-photon source. The technique involves…

Quantum Physics · Physics 2010-10-29 Shesha Raghunathan , Todd Brun

We show that injecting a light pulse prepared in the Shroedinger cat quantum state into the dark port of a two-arm interferometer and the strong classical light into the bright one, it is possible, in principle, to detect a given phase…

Quantum Physics · Physics 2024-05-29 V. L. Gorshenin