Measurement of the Statistical Distribution of Gaussian and Laser Sources

Arecchi, F. T.

doi:10.1103/physrevlett.15.912

Cited by 285 publications

(211 citation statements)

References 7 publications

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“…The scattered light forms a random spatial distribution of speckles whose average size is larger than the core diameter of a single-mode fiber used to collect it. When the ground glass disk rotates, light exits the fiber in a clean collimated spatial mode with random amplitude and phase fluctuations, yielding the photon distribution typical of a thermal source [17]. The product between the SPATS preparation rate and the coherence time of the injected thermal state (a few microseconds, and depending on the rotation speed of the disk) is kept much smaller than 1.…”

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Experimental determination of a nonclassical Glauber-SudarshanPfunction

et al. 2008

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A quantum state is nonclassical if its Glauber-Sudarshan P function fails to be interpreted as a probability density. This quantity is often highly singular, so that its reconstruction is a demanding task. Here we present the experimental determination of a well-behaved P function showing negativities for a single-photon-added thermal state. This is a direct visualization of the original definition of nonclassicality. The method can be useful under conditions for which many other signatures of nonclassicality would not persist. PACS numbers: 42.50.Dv, 42.50.Xa, 03.65.Ta, 03.65.Wj Einstein's hypothetical introduction of light quanta, the photons, was the first step toward the consideration of nonclassical properties of radiation [1]. But what does nonclassicality mean in a general sense? A radiation field is called nonclassical when its properties cannot be understood within the framework of the classical stochastic theory of electromagnetism. For other systems, nonclassicality can be defined accordingly. Here we will focus our attention on harmonic quantum systems, such as radiation fields or quantum-mechanical oscillators, for example trapped atoms.In this context the coherent states, first considered by Schrödinger in the form of wave packets [2], play an important role. They represent those quantum states that are most closely related to the classical behavior of an oscillator or an electromagnetic wave. For a single radiation mode, the coherent states |α are defined as the right-hand eigenstates of the non-Hermitian photon annihilation operatorâ,â|α = α|α ; cf. e.g. [3]. A general mixed quantum stateρ,can be characterized by the Glauber-Sudarshan P function [3,4]. In this form the quantum statistical averages of normally ordered operator functions can be written aswhere the normal ordering prescription :f (â,â † ) : means that all creation operatorsâ † are to be ordered to the left of all annihilation operatorsâ. Formally, the resulting expressions (2) for expectation values are equivalent to classical statistical mean values. However, in general, the P function does not exhibit all the properties of a classical probability density. It can become negative or even highly singular. Within the chosen representation of the theory, the failure of the Glauber-Sudarshan P function to show the properties of a probability density is taken as the key signature of quantumness [5,6].In this Rapid Communication we demonstrate the experimental determination of a nonclassical P function. Within the experimental precision it clearly attains negative values. This is a direct demonstration of nonclassicality: the negativity of the P function prevents its interpretation as a classical probability density.Why is it so difficult to demonstrate the nonclassicality directly on the basis of this original definition? Let us go back to a single photon as postulated by Einstein. Its P function iscf. e.g. [7]. Already in this case we get a highly singular distribution in terms of derivatives of the δ distribution, which cannot be in...

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Experimental determination of a nonclassical Glauber-SudarshanPfunction

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“…We reproduced a single mode of this pseudo-thermal light field by passing the coherent light of our laser source through an inhomogeneous diffusing medium and then selecting a single specklewithanaperture(∼ 150 µm diameter), much smaller than the coherence area of the speckle pattern produced (Arecchi, 1965). By delivering this pseudo-thermal light to the SiPM sensor, we measured the values of the output, x, at 50000 subsequent laser shots and at 10 different mean values, obtained by means of a variable neutral-density filter (ND in Fig.…”

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Silicon Photomultipliers: Characterization and Applications

Ramilli¹,

Allevi²,

Nardo³

et al. 2012

Photodetectors

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“…(10) mostra objetivo similar: incidindo radiação laser em um cilindro rotatório, "transparente", obtemos radiação espalhada tendo forma gaussiana, com largura controlável; a largura da gaussiana sendo definida pela velocidade de rotação do cilindro [17,18]. Não temos notícia sobre que forma de linha teria a radiação espalhada se o feixe laser incidisse em um cilindro rotatório contendo Figura 9: Esboço do arranjo experimental mostrando um feixe laser "monocromatico" atravessando solucão aquosa contendo partículas suspensas em movimento browniano.…”

Section: Alargamento Programadounclassified

Mecanismos de alargamento de linhas espectrais atômicas

Valverde

Baseia

Bagnato

2016

Rev. Bras. Ensino Fís.

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Recebido em 14 de abril de 2016. Aceito em 22 de maio de 2016Os espectros de energia deátomos idealizados (isolados, parados e em temperatura 0K) são constituídos por um conjunto de linhas muito estreitas. Contudo, no mundo real, verifica-se que cada uma destas linhas são alargadas pela ação de vários tipos de influências externas. Uma discussão simplificadaé apresentada sobre seus mecanismos e como cada um deles atua isoladamente sobre as linhas espectrais. O caso de dois ou mais mecanismos atuando juntosé também considerado. Técnicas de afinamento de linha para relevantes aplicações são mencionadas, incluindo algumas que usam o controle da largura e da forma da linha laser. Palavras-chave: alargamento de linha, afinamento de linha, linha do laser.The energy spectra of idealized atoms (isolated, at rest and temperature 0K) are constituted by a set of very narrow lines. However, in the real world one verifies that each of these lines are enlarged by the action of various types of external influences. A simplified discussion is presented about their mechanisms and how each type of them acts isolated upon a thin spectral line. The case of two or more types of these mechanisms acting conjunctly is also considered. Line narrowing techniques for relevant applications are mentioned, including others using the control of the widths and the shapes of a laser line.

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Measurement of the Statistical Distribution of Gaussian and Laser Sources

Cited by 285 publications

References 7 publications

Experimental determination of a nonclassical Glauber-SudarshanPfunction

Experimental determination of a nonclassical Glauber-SudarshanPfunction

Silicon Photomultipliers: Characterization and Applications

Mecanismos de alargamento de linhas espectrais atômicas

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