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A graded index metamaterial and its entangled photon pair generation system

A graded refractive index, photon pair technology, applied in the field of quantum information, can solve the problems of large device size, inability to achieve, and high pump power, and achieve the effects of improving conversion efficiency, enhancing local field, and low pump power

Active Publication Date: 2020-05-19
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Common integrated entangled photon pair generators based on spontaneous four-wave mixing include straight nanowaveguides, microcavities, and helical waveguides (Table 1), which have the following disadvantages: high pump power (at most ∼5 ×10 5 the s - 1 nm -1 ), large device size (the size of the entangled photon pair generator is greater than 300 μm 2 )
However, the existing graded-index media are only based on the mathematical model of continuous change in refractive index, which cannot be realized physically. Specifically, the realization of graded-index media requires materials with a refractive index close to zero, and light must be able to pass through conventional materials. transmitted into this zero-refractive-index material, and no material meeting these two conditions exists in nature

Method used

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  • A graded index metamaterial and its entangled photon pair generation system
  • A graded index metamaterial and its entangled photon pair generation system
  • A graded index metamaterial and its entangled photon pair generation system

Examples

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Embodiment 1

[0049] see Figure 1 to Figure 4 , a metamaterial with a graded refractive index in this embodiment includes a plurality of periodically arranged dielectric pillar arrays 8, each dielectric pillar array 8 is rectangular, and is composed of a plurality of dielectric pillars 81 arranged at intervals, each The cross-section of the dielectric column is circular or regular polygonal (such as regular triangle, square, regular hexagon, etc.); the direction parallel to the row and column of the dielectric column array 8 is used as the x-axis and the y-axis respectively, and the light incident The angle between the direction k and the x-axis is θ, 0≤θ≤90°; in the dielectric column array 8, assuming that the period b (ie row spacing) of the dielectric column array along the y-axis remains unchanged, the period along the x-axis and The diameter of the medium column is a i and d i (reference sign r in the figure i Indicates the radius of the medium column, and d i = 2r i ), in the sa...

Embodiment 2

[0061] see Figure 5 , the difference between this embodiment and Embodiment 1 is that each dielectric column array 8 is composed of three equilateral triangles (such as Figure 5 As shown in the triangle dotted line box in the middle, it should be noted that the triangle dotted line box is only a schematic diagram, not drawn to scale) composed of dielectric columns 81 distributed, and in the metamaterial of this embodiment, the center-to-center distance of all adjacent two dielectric columns Both are a and remain unchanged, 0.1λ 0 ≤a≤λ 0 ,λ 0 is the wavelength in free space, λ 0 ≥100nm; the diameter of each medium column d i Determined according to the following formula:

[0062] d i = d 0 n i

[0063] Among them, d 0 is the equivalent refractive index n eff The diameter of each medium column in the column whose real part is zero, The meanings of other symbols are the same as those in Example 1.

[0064] Figure 5 Shown is a schematic diagram of the structure o...

Embodiment 3

[0066] see Image 6 , the difference between this embodiment and Embodiment 1 is that each dielectric pillar array 8 is composed of six regular hexagons (such as Image 6 As shown in the hexagonal dotted line box, it should be noted that the hexagonal dotted line box is only a schematic diagram, not drawn to scale) composed of dielectric columns 81 distributed, and in the metamaterial of this embodiment, all two adjacent dielectric columns The distance between centers is a and remains unchanged, 0.1λ 0 ≤a≤λ 0 ,λ 0 is the wavelength in free space, λ 0 ≥100nm; the diameter of each medium column d i Determined according to the following formula:

[0067] d i = d 0 n i

[0068] Among them, d 0 is the equivalent refractive index n eff The diameter of each medium column in the column whose real part is zero, The meanings of other symbols are the same as those in Example 1.

[0069] Image 6 Shown is a schematic diagram of the structure of the metamaterial whose refrac...

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Abstract

The invention provides a metamaterial with a gradually changed refractive index, and an entanglement photon pair generation system thereof, and belongs to the field of quantum information. The metamaterial comprises a plurality of periodically-arranged dielectric column arrays. When the following conditions are met: in each row, the diameter or width of each dielectric column is regularly changedalong the row, and the period of each dielectric column is regularly changed or kept unchanged along the row; and in each column, when the diameter and the period of each dielectric column are both kept unchanged, a real part of an equivalent refractive index of the metamaterial is gradually changed from non-zero to zero and then becomes non-zero. The entanglement photon pair generation system comprises the metamaterial with the gradually changed refractive index, two narrow-band continuous tunable lasers, two polarization controllers, a beam splitter, an optical amplifier, a notch filter, a band-pass filter, an array waveguide grating, a single-photon detector and a time interval analyzer. The refractive index of the metamaterial is gradually changed physically; and the metamaterial is combined with integrated optics, and has the characteristics of low loss and CMOS compatibility.

Description

technical field [0001] The invention relates to the technical field of quantum information, in particular to a metamaterial with a graded refractive index and a system for generating entangled photon pairs. Background technique [0002] Quantum information science is the product of the combination of quantum mechanics and information science. The use of quantum mechanical systems can realize new forms of communication, calculation and measurement. The entangled photon pair formed by two photons has the following physical characteristics: when two photons are entangled with each other, no matter how far apart the two photons are, the state of the other photon can be obtained instantaneously by measuring one of the photons. In order to implement quantum information systems on a large scale, reliable and cost-effective sources of entangled photons are urgently needed. Furthermore, the integrated entangled photon source can miniaturize the generation of photon quantum states an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B1/00G02F1/01G02F1/35G02F1/39
CPCG02B1/002G02F1/0136G02F1/353G02F1/3536G02F1/39
Inventor 李杨
Owner TSINGHUA UNIV
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