CN114624940A - Two-photon polarization-path entangled quantum invisible state-transfer optical path - Google Patents

Two-photon polarization-path entangled quantum invisible state-transfer optical path Download PDF

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CN114624940A
CN114624940A CN202011432998.4A CN202011432998A CN114624940A CN 114624940 A CN114624940 A CN 114624940A CN 202011432998 A CN202011432998 A CN 202011432998A CN 114624940 A CN114624940 A CN 114624940A
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polarization
beam splitting
polarization beam
path
state
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刘慧�
李广兵
印娟
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Quantumctek Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/3501—Constructional details or arrangements of non-linear optical devices, e.g. shape of non-linear crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another

Abstract

The invention relates to a quantum invisible transmission-state optical path with two-photon polarization-path entanglement, which utilizes a pair of trapezoidal polarization beam splitting structures simultaneously integrated with polarization beam splitting and reflection functions to realize the beam splitting and beam combining of entangled photons, simultaneously inserts a wave plate between the two trapezoidal polarization beam splitting structures to realize the transmission-state preparation, and combines a double-tail fiber polarization beam splitting coupler to realize Bell-state measurement, thereby reducing the number of optical devices in an Alice end, realizing the Alice end with a compact optical structure, miniaturizing the structure and facilitating the integration of the Alice end, and under the optical design, conveniently realizing the alignment and adjustment of the optical path, having high stability and reducing the difficulty in debugging the optical path. In addition, a partial optical fiber structure is allowed to be realized in the optical path of the present invention, so that the stability of the entire optical path system is further enhanced.

Description

Two-photon polarization-path entangled quantum invisible state-transfer optical path
Technical Field
The invention relates to the technical field of quantum information science, in particular to a two-photon polarization-path entangled quantum invisible state-transfer optical path.
Background
Since 1993, Bennett et al proposed the concept of quantum invisible transport states, and since then there have been different groups demonstrating quantum invisible transport experiments based on different material carriers. Because the photon is less influenced by the environment, the italian Martini group demonstrates the quantum stealth state experiment by utilizing the polarization-path entanglement of the photon, and proves that the scheme is equivalent to the scheme proposed by Bennett et al, and the experimental optical path of the scheme is shown in fig. 1.
In the experimental optical path shown in fig. 1, pump light passes through the BBO crystal to generate down-converted entangled photons,
Figure BDA0002827259760000011
through calcite, photons of the H component enter 2 paths and are sent to Bob, and photons of the V component enter 1 path and are sent to Alice. The state of the photon pair at this time can be described as:
Figure BDA0002827259760000012
using polarization controllers acting on a1And b1On the path photon, any state to be transmitted can be prepared. For polarization-path entanglement, the 4 orthogonal Bell basis vectors used are as follows:
Figure BDA0002827259760000013
Figure BDA0002827259760000021
compared with the quantum invisible state entangled by four-photon polarization, Alice in the scheme can complete Bell measurement.
However, the experimental optical paths in the prior art are all constructed by space optical devices, so that the cost is high, the debugging difficulty is high, and the system stability is low.
Disclosure of Invention
Aiming at the problem, the invention provides a two-photon polarization-path entangled quantum invisible state-transfer optical path, wherein a part of space optical devices are subjected to substitution design, a part of optical fiber structures are realized, the cost is reduced, the debugging difficulty is reduced, and the system performance is more stable.
Specifically, the two-photon polarization-path entangled quantum invisible state-transfer optical path can comprise an entanglement source, an Alice end and a Bob end;
the entanglement source is used for generating entangled photons;
the Alice end is used for receiving the first path of entangled photons and carrying out initial transmission state preparation and Bell state measurement on the first path of entangled photons;
the Bob end is used for receiving the second path of entangled photons and carrying out single photon detection on the second path of entangled photons to reproduce a quantum state;
the device is characterized in that the Alice end comprises a first polarization beam splitting unit, a first polarization control module, a second polarization beam splitting unit and a Bell state measuring module, wherein:
the first polarization beam splitting unit is arranged to receive the first path of entangled photons, split its polarization into first and second components, and output the first and second components in parallel with each other;
the first polarization control module is arranged between the first polarization beam splitting unit and the second polarization beam splitting unit and is used for carrying out polarization state modulation on the first component and the second component to realize initial transmission state preparation;
said second polarization beam splitting element being arranged to receive said first and second components and to directionally deflect said first component so as to interfere with said second component at a polarization beam splitting plane to generate first and second interference signals;
the Bell state measurement module is configured to receive the first and second interference signals and perform single photon detection under four orthogonal Bell basis vectors to achieve Bell state measurements.
Further, the first polarization beam splitting unit includes a polarization beam splitter portion and a mirror portion integrated as one body, and a reflection surface of the mirror portion is parallel to a polarization beam splitting surface of the polarization beam splitter portion; and, the second polarization beam splitting unit includes a polarization beam splitter portion and a mirror portion integrated as one body, and a reflection surface of the mirror portion is parallel to a polarization beam splitting surface of the polarization beam splitter portion.
Further, the first polarization control module is further configured to flip one of the first and second components by 90 degrees.
Wherein the first polarization control module may include: the first polarization control unit is used for realizing the 90-degree turnover of the polarization state; and a second polarization control unit for implementing the initial transport state preparation.
Preferably, the first polarization control unit comprises a polarization controller or a wave plate; the second polarization control unit includes a polarization controller or a wave plate.
Optionally, the first polarization control unit is a wave plate of 1/4 wavelengths; the second polarization control unit includes a quarter-wave plate and a half-wave plate.
Furthermore, the Bell state measuring module comprises a third polarization control unit, a third polarization beam splitting unit, a fourth polarization control unit, a fourth polarization beam splitting unit and first to fourth single photon detection units; the third polarization control unit is arranged for polarization control of the first interference signal; the third polarization beam splitting unit is arranged to receive the polarization-controlled first interference signal and to split its polarization into first and second components; the first and second single-photon detection units are respectively arranged for single-photon detection of first and second components of the first interference signal; the fourth polarization control unit is configured to perform polarization control on the second interference signal; the fourth polarization beam splitting unit is arranged to receive the polarization-controlled second interference signal and to split its polarization into third and fourth components; the third and fourth single photon detection units are respectively arranged for single photon detection of the third and fourth quantums.
Still further, the third polarization control unit is configured to effect one of-45 degree and 45 degree polarization state rotation, and the fourth polarization control unit is configured to effect the other of-45 degree and 45 degree polarization state rotation.
Preferably, the third polarization control unit comprises a polarization controller or a wave plate, or is implemented by rotating the optical axis alignment angle; and/or the fourth polarization control unit comprises a polarization controller or a wave plate, or is realized by rotating the optical axis alignment angle.
Preferably, the third polarization beam splitting unit comprises a double-pigtail polarization beam splitting coupler, and the double-pigtail polarization beam splitting coupler is connected with the first and second single photon detection units through optical fibers; and/or the fourth polarization beam splitting unit comprises a double-pigtail polarization beam splitting coupler, and the double-pigtail polarization beam splitting coupler is connected with the third and fourth single photon detection units through optical fibers.
Further, the quantum invisible state light path can further comprise a first light collecting unit, and the Alice end further comprises a first collimator; wherein the content of the first and second substances,
the first light collection unit comprises a first coupler and a transmission fiber, the first coupler being arranged to collect and couple the first path of entangled photons into the transmission fiber;
the first collimator is arranged for coupling to the transmission fiber for collimating the first path of entangled photons.
Optionally, the transmission fiber is a single mode or polarization maintaining fiber.
Further, the quantum invisible state optical path can further comprise a polarization compensation unit arranged before or after the first collimator.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 illustrates a quantum invisible propagation experimental optical path of the prior art;
FIG. 2 illustrates one embodiment of a two-photon polarization-path entangled quantum invisible state optical path according to the present invention;
FIG. 3 illustrates another embodiment of a two-photon polarization-path entangled quantum invisible state optical path according to the present invention;
fig. 4 shows yet another embodiment of a two-photon polarization-path entangled quantum invisible propagation path according to the present invention.
Detailed Description
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are provided by way of illustration in order to fully convey the spirit of the invention to those skilled in the art to which the invention pertains. Accordingly, the present invention is not limited to the embodiments disclosed herein.
Fig. 2 shows an embodiment of a two-photon polarization-path entangled quantum invisible state optical path according to the present invention.
In the invention, the quantum invisible state-transfer optical path can comprise an entanglement source, an Alice end and a Bob end.
The entanglement source is used to generate polarization-entangled photons, which may be expressed, for example, as
Figure BDA0002827259760000051
Figure BDA0002827259760000052
And the Alice end is used for receiving the first path of the entangled photons and carrying out initial transmission state preparation and Bell state measurement on the first path of the entangled photons.
Specifically, the Alice end may include a first polarization beam splitting unit, a first polarization control module, a second polarization beam splitting unit, and a Bell-state measurement module.
The first polarization beam splitting unit is used for receiving the first path of entangled photons, splitting the polarization of the entangled photons into a first component and a second component, and outputting the first component and the second component in parallel with each other.
For example, when the traveling path of the first component transmitted at the polarization beam splitting surface is denoted as L and the traveling path of the reflected second component is denoted as R, the first entangled photon is acted by the first polarization beam splitting unit, and it can be expressed as:
Figure BDA0002827259760000053
the first polarization control module is arranged between the first polarization beam splitting unit and the second polarization beam splitting unit and used for carrying out polarization state modulation on the first component and the second component, and therefore initial transmission state preparation is achieved.
As an example, the first polarization control module may include a first polarization control unit and a second polarization control unit.
The first polarization control unit is used for enabling the polarization state of the first component to be inverted by 90 degrees.
The second polarization control unit is used for carrying out polarization state modulation on the first component and the second component, so that initial transmission state preparation is realized.
For example, the first path of entangled photons modulated in polarization state by the first polarization control module may be expressed as:
Figure BDA0002827259760000061
in the present invention, the first and second polarization control units may be implemented by a polarization controller, or by a wave plate. For example, the second polarization control unit may include a quarter-wave plate and a half-wave plate.
The second polarization beam splitting unit may have the same structure as the first polarization beam splitting unit, and is configured to receive the first and second components modulated in polarization state and parallel to each other, and deflect the first component by 90 degrees inside thereof (for example, by reflection) so as to interfere with the second component on the polarization beam splitting surface, thereby generating a first interference signal and a second interference signal. At this time, the first path of entangled photons can be expressed as:
Figure BDA0002827259760000062
the Bell state measuring module is used for receiving the first interference signal and the second interference signal and carrying out single photon detection under four orthogonal Bell basis vectors so as to realize Bell state measurement.
As an example, the Bell-state measurement module may include a third polarization control unit, a third polarization beam splitting unit, a fourth polarization control unit, a fourth polarization beam splitting unit, and first to fourth single-photon detection units.
The third polarization control unit is arranged before the third polarization beam splitting unit and is used for rotating the polarization state of the first interference signal by-45 degrees, and the third polarization beam splitting unit is used for splitting the first interference signal subjected to polarization state rotation into a first component and a second component.
The fourth polarization control unit is arranged before the fourth polarization beam splitting unit and used for enabling the polarization state of the second interference signal to be rotated by 45 degrees, and the fourth polarization beam splitting unit is used for splitting the second interference signal subjected to polarization state rotation into third and fourth components.
At this time, the first path of entangled photons may be expressed, for example, as:
Figure BDA0002827259760000071
wherein the first component, the second component, the third component and the fourth component correspond to | H |, respectively>1|R>，|V>1|R>，|H>1|L>，|V>1And L > performing single photon detection by the first to fourth single photon detection units respectively, thereby realizing Bell state measurement.
In the present invention, the third and fourth polarization control units may be implemented by a polarization controller, by a wave plate, or by rotating the optical axis alignment angle.
And the Bob end is used for receiving the second path of the entangled photons and carrying out single photon detection on the second path of the entangled photons to reproduce the quantum state.
Specifically, the Bob end may include a fifth polarization beam splitting unit, a fifth single photon detection unit, and a sixth single photon detection unit.
And the fifth polarization beam splitting unit is used for carrying out polarization beam splitting on the second path of entangled photons to form a first component and a second component.
The fifth and sixth single-photon detection units are respectively used for receiving the first and second components and carrying out single-photon detection on the first and second components.
In the embodiment of fig. 2, the first polarization beam splitting unit 1 in the Alice terminal may include a polarization beam splitter portion and a mirror portion, wherein a reflection surface of the mirror portion and a polarization beam splitting surface of the polarization beam splitter portion are parallel to each other. Thus, when a first path of entangled photons enters the first polarization beam splitting unit 1, first a first (transmitted) and a second (reflected) component are formed by polarization beam splitting at the polarization beam splitting surface of the polarization beam splitter portion, wherein the first component will leave the first polarization beam splitting unit 1 directly and the second component leaves the first polarization beam splitting unit 1 by reflection at the mirror portion, thereby achieving that the first and second components leave the first polarization beam splitting unit 1 in parallel with each other.
In the present invention, the polarization beam splitter portion and the mirror portion are integrated, and they may be bonded together by means of an optical glue, for example, to form a trapezoidal shape as shown in fig. 2.
The first polarization control unit 2 may comprise a quarter wave plate 2 to provide a polarization state flip of 90 degrees.
The second polarization control unit 3 may comprise a combination of a half wave plate and a quarter wave plate to produce the desired initial transmission state.
The second polarization beam splitting unit 4 may have the same structure as the first polarization beam splitting unit 1, and is arranged to allow the first component to propagate toward its polarization beam splitter portion after reflection by its mirror portion, and to allow the second component to interfere with the first component at its polarization beam splitter portion, generating first and second interference signals.
The third polarization control unit 5 may comprise a wave plate 5 for providing a polarization state rotation of-45 degrees for the optical signal.
The third polarization beam splitting unit 6 may comprise a double pigtail polarization beam splitting coupler 6 for receiving the first interference signal to split its polarization into a first and a second component and to transmit the first and second components to the first and second single photon detection units 9, 10 via transmission fibers, respectively.
The fourth polarization control unit 7 may comprise a wave plate 7 for providing a polarization state rotation of 45 degrees for the optical signal.
The fourth polarization beam splitting unit 8 may comprise a dual pigtail polarization beam splitting coupler 8 for receiving the second interference signal to split its polarization into third and fourth components and to transmit the third and fourth components to the third and fourth single photon detection units 11 and 12, respectively, via transmission fibers.
The first single photon detection unit 9 may comprise a single photon detector 9 to perform single photon detection of the first component; the second single photon detection unit 10 may comprise a single photon detector 10 to perform single photon detection of the second component; the third single-photon detection unit 11 may comprise a single-photon detector 11 to perform single-photon detection of the third component; the fourth single photon detection unit 12 may comprise a single photon detector 12 for single photon detection of the fourth component.
With continued reference to fig. 2, in Bob end, the fifth polarization beam splitting unit 13 may include a polarization beam splitter 13.
The fifth single photon detection unit may comprise a first coupler 14 and a fifth single photon detector 16, wherein the first coupler 14 is configured to collect the first component output by the polarization beam splitter 13 and input it to the fifth single photon detector 16 via a transmission fiber for single photon detection of the first component.
The sixth single photon detection unit may comprise a second coupler 15 and a sixth single photon detector 17, wherein the second coupler 15 is configured to collect the second component output by the polarization beam splitter 13 and input it to the sixth single photon detector 17 via the transmission fiber for single photon detection of the second component.
Fig. 3 illustrates another embodiment of a two-photon polarization-path entangled quantum invisible state optical path according to the present invention. For the sake of brevity, only the differences from the embodiment shown in fig. 2 will be described below, and the same contents will not be described again.
In this embodiment, the quantum invisible state optical path may further include a first light collection unit and a second light collection unit. In addition, a first collimator 18 and a second collimator 19 may be provided in the Alice end and the Bob end, respectively.
The first light collecting unit is used for collecting the first path of entangled photons output by the entanglement source and transmitting the first path of entangled photons into an Alice end by virtue of an optical fiber; the second light collecting unit is used for collecting the second path of entangled photons output by the entanglement source and transmitting the second path of entangled photons into the Bob end by means of the optical fiber.
As shown in fig. 3 in particular, the first light collecting unit may include a first coupler 20 and a transmission fiber 22, wherein the first coupler 20 is configured to collect and couple a first path of entangled photons into the transmission fiber 22, and then the first path of entangled photons in the transmission fiber 22 is input into the first polarization beam splitting unit 1 at Alice end through the first collimator 18.
The second light collecting unit may include a second coupler 21 and a transmission fiber 23, wherein the second coupler 21 is configured to collect and couple the second channel of entangled photons into the transmission fiber 23, and then the second collimator 19 inputs the second channel of entangled photons in the transmission fiber 23 into the fifth polarization beam splitting unit 13 at Bob end.
In a preferred example, a polarization compensation unit (e.g., a polarization controller or a wave plate) may also be provided to rectify polarization changes caused during distribution of entangled photons. For example, a polarization controller may be provided after the transmission fibers 22 and 23, or a wave plate may be provided after the collimators 18 and 19.
The transmission fibers 22 and 23 may be single mode fibers or polarization maintaining fibers. In the example of fig. 3, the transmission fibers 22 and 23 may be in the form of fiber jumpers.
Fig. 4 shows yet another embodiment of a two-photon polarization-path entangled quantum invisible propagation path according to the present invention. For the sake of brevity, only the differences from the embodiment shown in fig. 3 will be described below, and the same contents will not be described again.
As shown in fig. 4, in this embodiment, the fifth polarization beam splitting unit may include a fiber-type polarization-maintaining polarization beam splitter 24, the fifth single-photon detection unit may include a fifth single-photon detector 16, and the sixth single-photon detection unit may include a sixth single-photon detector 17. The fifth and sixth single photon detectors are respectively connected with two output ends of the optical fiber polarization-maintaining beam splitter 24 through transmission optical fibers.
Based on the above, in the quantum invisible transmission-state optical path, the splitting and combining of entangled photons are realized by utilizing a pair of trapezoidal polarization beam splitting structures which are integrated with polarization beam splitting and reflection functions at the same time, the transmission-state preparation is realized by inserting a wave plate between the two trapezoidal polarization beam splitting structures, and Bell-state measurement is realized by combining a double-tail fiber polarization beam splitting coupler, so that the number of optical devices in an Alice end can be reduced, and therefore, the Alice end with a compact optical structure is realized, the structure of the Alice end is miniaturized and is convenient to integrate. In addition, a partial optical fiber structure is allowed to be realized in the optical path of the present invention, so that the stability of the entire optical path system is further enhanced.
Although the present invention has been described in connection with the embodiments illustrated in the accompanying drawings, it will be understood by those skilled in the art that the embodiments described above are merely exemplary for illustrating the principles of the present invention and are not intended to limit the scope of the present invention, and that various combinations, modifications and equivalents of the above-described embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims (13)

1. A quantum invisible state-transfer optical path with two-photon polarization-path entanglement comprises an entanglement source, an Alice end and a Bob end;
the entanglement source is used for generating entangled photons;
the Alice end is used for receiving the first path of entangled photons and carrying out initial transmission state preparation and Bell state measurement on the first path of entangled photons;
the Bob end is used for receiving the second path of entangled photons and carrying out single photon detection on the second path of entangled photons to reproduce a quantum state;
the device is characterized in that the Alice end comprises a first polarization beam splitting unit, a first polarization control module, a second polarization beam splitting unit and a Bell state measuring module, wherein:
the first polarization beam splitting unit is arranged to receive the first path of entangled photons, split its polarization into first and second components, and output the first and second components in parallel with each other;
the first polarization control module is arranged between the first polarization beam splitting unit and the second polarization beam splitting unit and is used for carrying out polarization state modulation on the first component and the second component so as to realize initial transmission state preparation;
said second polarization beam splitting element being arranged to receive said first and second components and to directionally deflect said first component so as to interfere with said second component at a polarization beam splitting plane to generate first and second interference signals;
the Bell state measurement module is configured to receive the first and second interference signals and perform single photon detection under four orthogonal Bell basis vectors to achieve Bell state measurements.
2. The quantum invisible transit optical path of claim 1, wherein:
the first polarization beam splitting unit comprises a polarization beam splitter part and a reflecting mirror part which are integrated into a whole, and the reflecting surface of the reflecting mirror part is parallel to the polarization beam splitting surface of the polarization beam splitter part; and the number of the first and second electrodes,
the second polarization beam splitting unit includes a polarization beam splitter portion and a mirror portion integrated into one body, and a reflection surface of the mirror portion is parallel to a polarization beam splitting surface of the polarization beam splitter portion.
3. The quantum invisible state light path of claim 1, wherein the first polarization control module is further configured to flip one of the first and second components by 90 degrees.
4. The quantum invisible state optical path of claim 3, wherein the first polarization control module comprises: the first polarization control unit is used for realizing the 90-degree turnover of the polarization state; and a second polarization control unit for implementing the initial transport state preparation.
5. The quantum invisible propagation path of claim 4, wherein the first polarization control unit comprises a polarization controller or a wave plate; the second polarization control unit includes a polarization controller or a wave plate.
6. The quantum invisible transit state optical path of claim 4, wherein:
the first polarization control unit is a wave plate with the wavelength of 1/4;
the second polarization control unit includes a quarter-wave plate and a half-wave plate.
7. The quantum invisible state light path of claim 1, wherein the Bell state measuring module comprises a third polarization control unit, a third polarization beam splitting unit, a fourth polarization control unit, a fourth polarization beam splitting unit, and first to fourth single photon detection units;
the third polarization control unit is arranged for polarization control of the first interference signal;
the third polarization beam splitting unit is arranged to receive the polarization-controlled first interference signal and to split its polarization into first and second components;
the first and second single-photon detection units are respectively arranged for single-photon detection of first and second components of the first interference signal;
the fourth polarization control unit is configured to perform polarization control on the second interference signal;
the fourth polarization beam splitting unit is arranged to receive the polarization-controlled second interference signal and to split its polarization into third and fourth components;
the third and fourth single photon detection units are arranged for single photon detection of the third and fourth quantums, respectively.
8. The quantum invisible state optical path of claim 7, wherein the third polarization control unit is configured to achieve one of-45 degree and 45 degree polarization state rotation, and the fourth polarization control unit is configured to achieve the other of-45 degree and 45 degree polarization state rotation.
9. The quantum invisible transit optical path of claim 7, wherein:
the third polarization control unit comprises a polarization controller or a wave plate or is realized by means of rotating the optical axis to align the angle; and/or the like, and/or,
the fourth polarization control unit comprises a polarization controller or a wave plate, or is realized by rotating the optical axis alignment angle.
10. The quantum invisible transit optical path of claim 7, wherein:
the third polarization beam splitting unit comprises a double-pigtail polarization beam splitting coupler, and the double-pigtail polarization beam splitting coupler is connected with the first single photon detection unit and the second single photon detection unit through optical fibers; and/or the like, and/or,
the fourth polarization beam splitting unit comprises a double-pigtail polarization beam splitting coupler, and the double-pigtail polarization beam splitting coupler is connected with the third and fourth single photon detection units through optical fibers.
11. The quantum invisible state light path of any one of claims 1-10, further comprising a first light collecting unit, and the Alice end further comprises a first collimator; wherein, the first and the second end of the pipe are connected with each other,
the first light collection unit comprises a first coupler and a transmission fiber, the first coupler being arranged to collect and couple the first path of entangled photons into the transmission fiber;
the first collimator is arranged for coupling to the transmission fiber for collimating the first path of entangled photons.
12. The quantum invisible propagation optical path of claim 11, wherein the transmission fiber is a single mode or polarization maintaining fiber.
13. The quantum invisible conduction optical path of claim 11, further comprising a polarization compensation unit disposed before or after the first collimator.
CN202011432998.4A 2020-12-10 2020-12-10 Two-photon polarization-path entangled quantum invisible state-transfer optical path Pending CN114624940A (en)

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