Gaussian modelling and Schmidt modes of SPDC biphoton states

Федоров, М. В.; Mikhailova, Yu. M.; Volkov, P. A.

doi:10.1088/0953-4075/42/17/175503

Cited by 66 publications

(56 citation statements)

References 8 publications

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“…It has been shown that the Schmidt modes for the SPDC biphoton state are given by the Hermite Gaussian polynomials [26,27]. Therefore they show a certain symmetry:…”

Section: Interferometric Scheme and Measurementmentioning

confidence: 99%

Transverse entanglement of biphotons

et al. 2013

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We measure the transverse entanglement of photon pairs on their propagation from the near to the far field of spontaneous parametric downconversion (SPDC). The Fedorov ratio, depending on the widths of conditional and unconditional intensity measurements, is shown to be only able to characterize entanglement in the near and far field zones of the source. Therefore we also follow a different approach. By evaluating the first-order coherence of a subsystem of the state we can quantify its entanglement. Unlike previous measurements, which determine the Fedorov ratio via intensity correlations, our setup is sensitive to both phase and modulus of the biphoton state and thus always grants experimental access to the full transverse entanglement of the SPDC state. It is shown theoretically that this scheme represents a direct measurement of the Schmidt number.

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“…It has been shown that the Schmidt modes for the SPDC biphoton state are given by the Hermite Gaussian polynomials [26,27]. Therefore they show a certain symmetry:…”

Section: Interferometric Scheme and Measurementmentioning

confidence: 99%

Transverse entanglement of biphotons

et al. 2013

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“…We will analyze the entanglement by performing Schmidt decomposition of the two-photon state, which is known as a useful approach to characterize bi-partite pure-state entanglement [45][46][47]. Such an approach has been applied to various atomic and optical systems [48][49][50][51][52][53][54][55].…”

Section: Introductionmentioning

confidence: 99%

Scattering of two distinguishable photons by aΞ-type three-level atom in a one-dimensional waveguide

Huang

Law

2015

Phys. Rev. A

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We investigate theoretically quantum scattering of two distinguishable photon wave packets from a -type three-level atom in a one-dimensional waveguide. The quantum state of scattered photons is solved analytically, and the solution indicates how the two photons become strongly correlated after the scattering. We determine the two-photon reflection and transmission properties, and analyze the quantum entanglement between the scattered photons. In particular, we show that the degree of entanglement can be enhanced by decreasing the spectral width of the incident photon wave packets.

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“…the whole dimensionality of the biphoton in the two-dimensional transverse space supposed isotropic. For an unidimensional system, V becomes the square of the Schmidt number 23 .…”

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confidence: 99%

Einstein-Podolsky-Rosen Paradox in Twin Images

2014

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Spatially entangled twin photons provide both promising resources for modern quantum information protocols, because of the high dimensionality of transverse entanglement 1,2 , and a test of the Einstein-Podolsky-Rosen (EPR) paradox 3 in its original form of position versus impulsion. Usually, photons in temporal coincidence are selected and their positions recorded, resulting in a priori assumptions on their spatio-temporal behavior 4 . Here, we record on two separate electron-multiplying charge coupled devices (EMCCD) cameras twin images of the entire flux of spontaneous down-conversion. This ensures a strict equivalence between the subsystems corresponding to the detection of either position (image or near-field plane) or momentum (Fourier or far-field plane) 5 . We report the highest degree of paradox ever reported and show that this degree corresponds to the number of independent degrees of freedom 6,7 or resolution cells 8 , of the images.In 1935, Einstein, Podolsky and Rosen (EPR) showed that quantum mechanics predicts that entangled particles could have both perfectly correlated positions and momenta, in contradiction with the so-called local realism where two distant particles should be treated as two different systems. Though the original intention of EPR was to show that quantum mechanics is not complete, the standard present view is that entangled particles do experience nonlocal correlations 9,10 . It can be shown that the spatial extent of these correlations corresponds to the size of a spatial unit of information, or mode, offering the possibility of detecting high dimensional entanglement in an image with a sufficient number of resolution cells 2,4 . However, in most experiments the use of single photon detectors and coincidence counting leads to the detection of a very few part of selected photons, generating a sampling loophole in fundamental demonstrations. High sensitivity array detectors have been used outside the single photoncounting regime in order to witness the quantum feature of light, showing the possibility of achieving larger signal-tonoise ratio than in classical imaging 11,12 . However, the EPR paradox is intimately connected to the particle character of light and its detection should involve single photon imaging, possible either with intensified charge coupled devices (ICCD) or, more recently, EMCCDs 13 . ICCDs exhibit a lower noise but have also a lower quantum efficiency than EMCCDs and a more extended spatial impulse response. ICCD are therefore convenient to isolate pairs of entangled photons 14 , as shown in a recent experiment: an ICCD triggered by a single photon detector was used to detect heralded photons in various spatial modes 15 .On the other hand, because of their higher quantum efficiency EMCCDs allow efficient detection of quantum correlations in images, as demonstrated some years ago by measuring sub-shot-noise correlations in far-field images of spontaneous parametric down-conversion (SPDC) 16,17 . More recently, two experiments intended to achieve the demonstra...

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Gaussian modelling and Schmidt modes of SPDC biphoton states

Cited by 66 publications

References 8 publications

Transverse entanglement of biphotons

Transverse entanglement of biphotons

Scattering of two distinguishable photons by aΞ-type three-level atom in a one-dimensional waveguide

Einstein-Podolsky-Rosen Paradox in Twin Images

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