A continuous variable bidirectional quantum teleportation device and its application

Abstract

The present invention discloses a continuous variable bidirectional quantum teleportation device, comprising an interconnected entangled source, an input optical path, and an output optical path. The input optical path and the output optical path of the scheme both comprise a beam splitter with an adjustable splitting ratio, two beam splitters, two balanced zero-beat detectors, an amplitude modulator, and a phase modulator. The beam splitter with an adjustable splitting ratio is connected to the EPR entangled source, the two balanced zero-beat detectors of the input optical path are respectively connected to the amplitude modulator and the phase modulator of the output optical path, and the two balanced zero-beat detectors of the output optical path are respectively connected to the amplitude modulator and the phase modulator of the input optical path. The continuous variable bidirectional quantum teleportation scheme provided by the present invention can realize a bidirectional teleportation process under a pair of EPR entangled lights. Using this scheme to construct a quantum network and quantum conference can significantly increase the number of users that can be carried in the network and conference under fixed entangled resources.

Description

Technical Field

[0001] The present invention relates to the field of quantum optics technology, and in particular to a continuous variable bidirectional quantum teleportation device and its application. Background Art

[0002] Quantum teleportation is one of the most important protocols in the field of quantum information, playing a key role in the continued development of quantum computing, quantum communication, and quantum networks. Because continuous variable systems have infinite-dimensional Hilbert spaces and are deterministic in experiments, quantum teleportation has rapidly developed since its extension to continuous variable systems.

[0003] Currently, continuous variable quantum teleportation can achieve a high degree of information reconstruction. In protocols, the concept of fidelity is generally used to describe the degree of information reconstruction of the input state. The highest fidelity achieved in experiments has reached 0.905, which almost completely reconstructs the input state. However, existing quantum teleportation schemes can only achieve one-way high-fidelity information transmission. With only one experimental setup, the input and output ports cannot be interchanged, and bidirectional information transmission is impossible. Therefore, a continuous variable quantum teleportation scheme that can achieve bidirectional transmission is needed. Summary of the Invention

[0004] Addressing the shortcomings of existing technologies, this invention proposes a continuous-variable bidirectional quantum teleportation device and its applications. This device boasts a rational and compact optical path layout, convenient installation and adjustment of optical components, and simple operation, enabling high-fidelity bidirectional information transmission. This device utilizes adjustable-splitting-ratio beam splitter technology, electro-optical modulation, and balanced zero-beat detection techniques to successfully achieve bidirectional continuous-variable quantum teleportation using a single experimental setup and a pair of EPR entangled beams.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A continuous variable bidirectional quantum teleportation device includes an interconnected EPR entangled source, an input light path, and an output light path, wherein the input light path includes a first beam splitter with an adjustable splitting ratio, a first beam splitter, a second beam splitter, a first balanced zero-beat detector, a second balanced zero-beat detector, a first amplitude modulator, and a first phase modulator. A beam of entangled light in the EPR entangled source is projected onto the input light path. The first beam splitter with an adjustable splitting ratio couples a beam of EPR entangled light in the EPR entangled source with signal light containing input state information to be measured and separates the coupled light beams according to the splitting ratio, and projects them onto the first beam splitter and the second beam splitter, respectively. The first beam splitter and the second beam splitter respectively couple a beam of local light and then project them onto the first balanced zero-beat detector and the second balanced zero-beat detector, respectively. The input light path is connected to the output light path via a first amplitude modulator and a first phase modulator, and the output light path has the same structure as the input light path.

[0007] Preferably, the local light is a strongly coherent light having the same frequency as the signal light.

[0008] Preferably, the output light path includes a second beam splitter with adjustable splitting ratio, a third beam splitter, a fourth beam splitter, a third balanced zero-beat detector, a fourth balanced zero-beat detector, a second amplitude modulator and a second phase modulator.

[0009] Preferably, the splitting ratio of the first beam splitter with adjustable splitting ratio is set to 50:50.

[0010] Preferably, the splitting ratio of the second beam splitter with adjustable splitting ratio is set to 99:1.

[0011] Preferably, the first balanced zero-beat detector locks the detection system to the phase of amplitude detection for detecting the amplitude component, and the second balanced zero-beat detector locks the detection system to the phase of phase detection for detecting the phase component.

[0012] Preferably, the first balanced zero-beat detector and the second amplitude modulator are used to receive the detected electrical signal and modulate it before inputting it into the output light path in the form of an optical signal.

[0013] Preferably, the second balanced zero-beat detector and the second phase modulator are used to receive the detected electrical signal and modulate it before inputting it into the output optical path in the form of an optical signal.

[0014] The present invention also provides an application of a device, wherein the device is the above-mentioned continuous variable bidirectional quantum teleportation device.

[0015] The present invention has the following characteristics and beneficial effects:

[0016] 1. The use of EPR entangled state as entanglement resource can ensure the "invisibility" of information transmission throughout the process, with extremely strong security and confidentiality.

[0017] Second, a beam splitter with an adjustable splitting ratio is added to the optical path, so that the input optical path and the output optical path can be interchanged by changing the splitting ratio of the beam splitter with an adjustable splitting ratio, which simplifies the experimental operation and does not require another set of experimental equipment to achieve two-way communication.

[0018] 3. The bidirectional solution can complete non-real-time quantum teleportation in two directions with only one pair of entangled resources and without changing the optical path, thus saving entangled resources.

[0019] 4. The detector uses a balanced zero-beat detector, which is more accurate in detecting amplitude and phase components.

[0020] 5. The detection results in the scheme are in the form of electrical signals, which are convenient for analysis and transmission using classical methods, and can be modulated using an optoelectronic modulator, which is more conducive to signal optimization.

[0021] 6. The adoption of a two-way solution can enable quantum networks and quantum conferences constructed using quantum teleportation to carry more users and expand the scope of the network or conference.

[0022] 7. In a ring network using a two-way solution, the entire network will not be paralyzed due to the disconnection of two users as in a one-way solution, making the entire quantum network more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 2 is a diagram of an apparatus according to an embodiment of the present invention.

[0025] In the figure, 1, input light path; 2, EPR entangled source; 3, output light path; 1-1, first variable beam splitter (VBS) (beam splitting ratio is 50:50); 1-2, first beam splitter (BS) (beam splitting ratio is 50:50); 1-3, second beam splitter (BS) (beam splitting ratio is 50:50); 1-4, first balanced zero-beat detector (BHD); 1-5, second balanced zero-beat detector (BHD); 1-6, first amplitude modulator (AM); 1-7, first phase modulator (PM); 3-1. Second adjustable beam splitter (VBS) (beam splitting ratio is 99:1); 3-2. Third beam splitter (BS) (beam splitting ratio is 50:50); 3-3. Fourth beam splitter (BS) (beam splitting ratio is 50:50); 3-4. Third balanced zero-beat detector (BHD); 3-5. Fourth balanced zero-beat detector (BHD); 3-6. Second amplitude modulator (AM); 3-7. Second phase modulator (PM). DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0029] Example 1

[0030] The present invention provides a continuous variable bidirectional quantum teleportation device, such as Figure 1 As shown, it includes an EPR entanglement source 2, an input light path 1, and an output light path 3.

[0031] Specifically, in this embodiment, the input light path 1 includes a first beam splitter with adjustable splitting ratio 1-1, a first beam splitter 1-2, a second beam splitter 1-3, a first balanced zero-beat detector 1-4, a second balanced zero-beat detector 1-5, a first amplitude modulator 1-6, and a first phase modulator 1-7. The first beam splitter with adjustable splitting ratio 1-1 couples a beam of EPR entangled light from the EPR entangled source 2-1 with a signal light containing the input state information to be measured and separates the coupled light beam according to the splitting ratio, projecting the light beam onto the first beam splitter 1-2 and the second beam splitter 1-3, respectively. In this embodiment, the splitting ratio of the first beam splitter with adjustable splitting ratio 1-1 is set to 50:50. At the first beam splitter 1-2, the coupled light beam is coupled with a beam of local light, and the coupled light beam enters the first balanced zero-beat detector 1-4; at the second beam splitter 1-3, the coupled light beam is coupled with another beam of local light, and the coupled light beam enters the second balanced zero-beat detector 1-5. It should be noted that the local light coupled by the first beam splitter and the second beam splitter is a highly coherent light with the same frequency as the signal light.

[0032] This process is the process of information encryption: due to the characteristics of entangled light, when the signal light containing information is coupled with only one beam of entangled light, the signal of the information contained will be masked by the thermal noise contained in this beam of entangled light. The signal detected by the coupled light beam will be a noise signal, and the information signal cannot be extracted by conventional means. That is, the information to be transmitted will be submerged in the thermal noise of the entangled light.

[0033] The output optical path 3 of the described scheme includes a second beam splitter with an adjustable splitting ratio 3-1, a third beam splitter 3-2, a fourth beam splitter 3-3, a third balanced zero-beat detector 3-4, a fourth balanced zero-beat detector 3-5, a second amplitude modulator 3-6, and a second phase modulator 3-7. The first balanced zero-beat detector 1-4 and the second balanced zero-beat detector 1-5 in the input optical path 1 are connected to the second amplitude modulator 3-6 and the second phase modulator 3-7, respectively, via classical channels (solid lines). The first and second balanced zero-beat detectors 1-4 and 1-5 transmit amplitude and phase information to the second amplitude modulator 3-6 and the second phase modulator 3-7 in the output optical path 3, respectively. The modulated light beam is transmitted to the second beam splitter with an adjustable splitting ratio 3-1, where it couples with another EPR entangled light beam from the EPR entangled source 2-1. The coupled light beam is then split according to the splitting ratio and projected onto the third beam splitter 3-2 and the fourth beam splitter 3-3, respectively. The second adjustable-splitting-ratio beam splitter 3-1 has a splitting ratio of 99:1. A local beam is coupled to the third beam splitter 3-2, and the coupled beam enters the third balanced zero-beat detector 3-4. Another local beam is coupled to the fourth beam splitter 3-3, and the coupled beam enters the fourth balanced zero-beat detector 3-5.

[0034] This is the information decryption process: Due to the properties of entangled light, when the signal light is coupled with one of the entangled beams, the detected signal will have a large amount of thermal noise, which will drown out the information in the signal light. However, after coupling with the other entangled light beam, the thermal noise is significantly reduced, allowing the information signal originally obscured by the thermal noise to be revealed and detected by the detection equipment at the output end. This completes the forward quantum teleportation process.

[0035] It can be understood that the output light path (3) has the same structure as the input light path (1). Therefore, by changing the splitting ratio setting of the first splitting ratio adjustable beam splitter 1-1 and the second splitting ratio adjustable beam splitter 3-1, the input light path and the output light path can be exchanged, thereby completing the reverse transmission and further realizing bidirectional transmission.

[0036] Example 2

[0037] The difference between this embodiment and embodiment 1 is that to complete the reverse state transmission, the input light path and the output light path need to be exchanged. Specifically, the output light path 3 is transformed into the input light path 3, including a second beam splitter with adjustable splitting ratio 3-1, a third beam splitter 3-2, a fourth beam splitter 3-3, a third balanced zero-beat detector 3-4, a fourth balanced zero-beat detector 3-5, a second amplitude modulator 3-6, and a second phase modulator 3-7. The splitting ratio of the second beam splitter with adjustable splitting ratio 3-1 is adjusted to 50:50. After that, a beam of EPR entangled light in the EPR entangled source 2-1 is coupled with the input state light field and the coupled light beams are separated according to the splitting ratio and projected onto the third beam splitter 3-2 and the fourth beam splitter 3-3 respectively. It will be coupled with a beam of local light at the third beam splitter 3-2, and the coupled beam will enter the third balanced zero-beat detector 3-4; it will be coupled with another beam of local light at the fourth beam splitter 3-3, and the coupled beam will enter the fourth balanced zero-beat detector 3-5.

[0038] In this embodiment, the input optical path 1 becomes the output optical path 1 during the reverse process, comprising a first beam splitter with an adjustable splitting ratio 1-1, a first beam splitter 1-2, a second beam splitter 1-3, a first balanced zero-beat detector 1-4, a second balanced zero-beat detector 1-5, a first amplitude modulator 1-6, and a first phase modulator 1-7. The third balanced zero-beat detector 3-4 and the fourth balanced zero-beat detector 3-5 in the input optical path 3 are connected to the first amplitude modulator 1-6 and the first phase modulator 1-7, respectively, via classical channels (dashed lines). The detectors transmit amplitude and phase information to the first amplitude modulator 1-6 and the first phase modulator 1-7 in the output optical path 1, respectively. The modulated light beam is then transmitted to the second beam splitter with an adjustable splitting ratio 3-1, where it is coupled with another EPR entangled light beam from the EPR entangled source 2. The coupled light beam is then split according to the splitting ratio and projected onto the first beam splitter 1-2 and the second beam splitter 1-3, respectively. At the first beam splitter 1-2, a local beam is coupled to the light, which enters the first balanced zero-beat detector 1-4. At the second beam splitter 1-3, another local beam is coupled to the light, which enters the second balanced zero-beat detector 1-5. This completes the reverse quantum teleportation process.

[0039] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments, including components, without departing from the principles and spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. A continuous variable bidirectional quantum teleportation device, characterized in that: The invention comprises an EPR entangled source (2), an input light path (1), and an output light path (3) connected to each other, wherein the input light path (1) comprises a first beam splitter (1-1) with adjustable beam splitting ratio, a first beam splitter (1-2), a second beam splitter (1-3), a first balanced zero-beat detector (1-4), a second balanced zero-beat detector (1-5), a first amplitude modulator (1-6), and a first phase modulator (1-7), and a beam of entangled light in the EPR entangled source (2) is projected onto the output light path (3). The light input path (1) is characterized in that the first beam splitter (1-1) with adjustable splitting ratio couples a beam of EPR entangled light in the EPR entangled source (2) with a signal light containing input state information to be measured and separates the coupled light beams according to the splitting ratio, and projects them onto the first beam splitter (1-2) and the second beam splitter (1-3), respectively. The first beam splitter (1-2) and the second beam splitter (1-3) respectively couple a beam of local light, and then project them onto the first balanced zero-beat detector (1-4) and the second balanced zero-beat detector (1-5). Two balanced zero-beat detectors (1-5), the input light path (1) is connected to the output light path (3) through a first amplitude modulator (1-6) and a first phase modulator (1-7), the output light path (3) includes a second beam splitter with adjustable splitting ratio (3-1), a third beam splitter (3-2), a fourth beam splitter (3-3), a third balanced zero-beat detector (3-4), a fourth balanced zero-beat detector (3-5), a second amplitude modulator (3-6) and a second phase modulator (3-7), the third balanced zero-beat detector (3-4) and the fourth balanced zero-beat detector (3-5) in the output optical path 3 are respectively connected to the first amplitude modulator (1-6) and the first phase modulator (1-7), the first balanced zero-beat detector (1-4) is connected to the second amplitude modulator (3-6), and the second balanced zero-beat detector (1-5) is connected to the second phase modulator (3-7), and the output optical path (3) has the same structure as the input optical path (1).

2. A continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The local light is a highly coherent light with the same frequency as the signal light.

3. A continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The beam splitting ratio of the first beam splitter (1-1) with adjustable beam splitting ratio is set to 50:

50.

4. A continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The beam splitting ratio of the second beam splitter (3-1) with adjustable beam splitting ratio is set to 99:

1.

5. The continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The first balanced zero-beat detector (1-4) locks the detection system to the phase of amplitude detection for detecting the amplitude component, and the second balanced zero-beat detector (1-5) locks the detection system to the phase of phase detection for detecting the phase component.

6. The continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The first balanced zero-beat detector (1-4) is used to receive the detected electrical signal and modulate it before inputting it into the output light path in the form of an optical signal.

7. The continuous variable bidirectional quantum teleportation device according to claim 1, characterized in that: The second balanced zero-beat detector (1-5) is used to receive the detected electrical signal and modulate it, and then input it into the output light path in the form of an optical signal.

8. An application of a device, characterized in that, Application of a continuous variable bidirectional quantum teleportation device according to any one of claims 1 to 7 in secure communications.

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