Measurement method of coherent-vortex topological charge based on two-photon association

A topological charge and two-photon technology, applied in the field of quantum sensing, can solve the problems of difficult to accurately identify the vortex topological information of the light source, restrict the accuracy of the measurement signal, etc., and achieve the effect of intuitive measurement results and large measurement range.

Pending Publication Date: 2018-04-20
CHINA JILIANG UNIV
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Problems solved by technology

The thermal noise of the light source seriously restricts the improvement of the accuracy of the measurement signal, making it difficult to accurately identify the vortex topology information of the light source at the single-photon level

Method used

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  • Measurement method of coherent-vortex topological charge based on two-photon association
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  • Measurement method of coherent-vortex topological charge based on two-photon association

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Embodiment Construction

[0016] The present invention will be described in further detail below in conjunction with the examples, and the following examples are explanations of the present invention.

[0017] figure 1 is a schematic diagram for one embodiment of the present invention. It includes: a dual-mode correlated laser 1; a beam splitter 2; a first bandpass filter 3; a first spatial light modulator 4; a first computer 5; a second bandpass filter 6; a second spatial light modulator 7 the second computer 8; the first lens 9; the first single-mode fiber 10; the first avalanche photodiode 11; the second lens 12; the second single-mode fiber 13; computer16.

[0018] See attached figure 1 , the working steps of a coherent vortex topological charge measurement method based on two-photon correlation are as follows:

[0019] 1. The dual-mode correlated laser 1 produces Gaussian entangled two-photon pairs; the wave function of the Gaussian entangled photon pairs is:

[0020] ψ in (x 1 ,y 1 ; x 2...

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Abstract

The invention relates to a measurement method of a coherent-vortex topological charge based on two-photon association. The measurement method of the coherent-vortex topological charge based on two-photon association comprises the following steps of generating a noncoherent entanglement photon pair; dividing the entanglement photon pair into an i photon and an s photon through a beam splitter; controlling a computer and making the s photon passing through a spatial light modulator acquire a vortex phase, then coupling an optical signal to a single mode fiber and using an avalanche diode to carry out single point measurement; controlling the computer and making the i photon passing through the spatial light modulator acquire a specific amplitude and a phase, then coupling the optical signalto the single mode fiber and using the avalanche diode to carry out single point measurement; associating and calculating the two paths of measured optical signals and using the computer to record; and through changing a transmission coefficient of the spatial light modulator of an optical path where the i photon is located, searching a maximum value of an output association value, wherein an i photon transmission coefficient corresponding to the maximum value is a vortex topological charge value of the s photon. In the invention, the noncoherent entanglement photon pair is taken as a light source; on a single photon level, a topological charge of a coherent vortex is measured; and advantages of an accurate measurement result and a large measurement range are possessed.

Description

technical field [0001] The invention relates to a method for measuring coherent vortex topological charge based on two-photon correlation, which belongs to the field of quantum sensing. technical background [0002] The vortex beam is a special light field with a spiral phase wavefront, the phase distribution function of the light field is exp(ilθ), and each photon of this light field carries a specific orbital angular momentum where l is called the topological charge and θ is the azimuth angle. For partially coherent light with poor coherence, generally there is no optical vortex with zero intensity, but there is a coherent vortex with zero spectral coherence or mutual coherence function. The topological charge of coherent vortex has important application prospects in optical tweezers, laser communication and quantum cryptography. The orbital angular momentum state |l> of photons has completeness, orthogonality and infinite dimensions, and it has been demonstrated that i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01J11/00
CPCG01J11/00
Inventor 陈君李耀
Owner CHINA JILIANG UNIV
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