CN105490751B - Any long-range combined preparation process of two-photon state based on linear optical element - Google Patents

Abstract

The present invention provides a kind of any long-range combined preparation process of two-photon state based on linear optical element, and methods described participant shares three, including first sender, second sender and a recipient；First sender, the second sender, recipient share M five photon entanglement states, wherein, preparation person of first sender as five photon entanglement states, first sender possesses the first photon and three-photon of each five photon entanglements state, second sender possesses the 4th photon of each five photon entanglements state, and recipient possesses the second photon and the 5th photon of each five photon entanglements state.The present invention shares a five photon entanglement state cans by two senders and a recipient and realizes prepared by the long-range joint of any two-photon state, communication efficiency is high, feasibility is strong, and the realization of scheme can need not tangle channel using maximum, greatly save the cost of scheme implementation and reduce the technical requirements of embodiment.

Description

Remote Joint Preparation of Arbitrary Two-Photon States Based on Linear Optical Elements

technical field

The invention relates to the field of communication technology, in particular to a method for remote joint preparation of arbitrary two-photon states based on linear optical elements.

Background technique

As we all know, current communication channels transmit digital or analog signals. Due to the non-ideal frequency response characteristics of the channel, noise interference and other interference mixed in when the signal is transmitted through the channel, the transmitted signal is damaged and the received signal waveform is distorted or the received digital signal symbol is wrong. For this kind of interference, there are currently two ways to ensure the correct transmission of the channel: one is to improve the performance and quality of lines and transmission equipment, such as using optical fibers; the other is to use error control strategies, such as cyclic redundancy check method Wait. However, improving lines and equipment requires technology updates and a large amount of investment, while using error checking will inevitably waste communication resources and slow down communication speed. Therefore, ensuring the correct transmission of information has always been an urgent problem in classical network communication. With the development of quantum information technology, some network communication methods based on quantum characteristics have been proposed one after another, such as quantum key distribution (QKD), quantum secure direct communication (QSDC), quantum secret sharing (QSS), and quantum teleportation ( QT) etc. These communication methods mainly use microscopic particles as information carriers, relying on some of their unique quantum properties, such as coherence, entanglement, etc., to avoid interference during transmission, and have unconditional security and accuracy. In this context, the use of quantum information technology to solve the problem of information transmission has received more and more attention.

Quantum communication uses the quantum state as the information carrier, and the security of the information loaded on the quantum state is guaranteed by the basic principles of quantum mechanics such as uncertainty relations. One of the important tasks of quantum communication in the quantum state preparation and transmission chamber. The optical quantum state has become an ideal information carrier for quantum communication because of its fast transmission speed and long distance. In recent years, the remote preparation of optical quantum states, especially the remote joint preparation, has attracted extensive attention of researchers from all over the world and has made research progress.

In recent years, the multi-party joint preparation technology of optical quantum states has attracted extensive attention from researchers, and a multi-party joint preparation scheme of optical quantum states under different equipment has been proposed. For example, in 2008, a multi-party joint preparation method for arbitrary single-photon states based on linear optical elements was proposed: the remote preparation scheme for arbitrary single-photon states based on linear optical elements only requires arbitrary single-photon states |φ>=α ₀ |0>+α ₁ |1>, (|α ₀ | ² +|α ₁ | ² ＝1, α ₀ , α ₁ are arbitrary complex numbers) two coefficients α ₀ , α ₁ set two beam splitter coefficients to realize any single photon state Remote preparation of |φ>. However, as the number of photons increases, the multi-photon state coefficient increases exponentially. The remote preparation of any multi-photon state is much more complicated than the remote preparation of any single-photon state, and the existing arbitrary single-photon state scheme is difficult to be extended to the multi-photon state.

Contents of the invention

In view of the various problems faced in the background technology, the purpose of the present invention is to provide a remote joint preparation method of any two-photon state based on linear optical elements. Starting from the actual operability, M five-photon entangled states are used as quantum information The transmission channel is completed with the participation of two senders and one receiver, and the remote joint preparation of any two-photon state is carried out.

In order to achieve the above-mentioned purpose, the technical solution adopted in the present invention is: a remote joint preparation method of any two-photon state based on a linear optical element. There are three participants in the method, including a first sender and a second sender. and a receiver; the first sender, the second sender, and the receiver share M five-photon entangled states, where the first sender is the producer of the five-photon entangled state, and the first sender owns each five-photon entangled state The first photon and the third photon of the state, the second sender has the fourth photon of each five-photon entanglement state, and the receiver has the second photon and the fifth photon of each five-photon entanglement state; assuming that the quantum state to be prepared is |ψ>=α ₀₀ |00>+α ₀₁ |01>+α ₁₀ |10>+α ₁₁ |11>, where α ₀₀ , α ₀₁ , α ₁₀ , and α ₁₁ are any complex numbers that satisfy the normalization relationship |α ₀₀ | ² +|α ₀₁ | ² +|α ₁₀ | ² +|α ₁₁ | ² = 1;

The concrete steps of described method are as follows:

Step 1: The first sender, the second sender, and the receiver share M five-photon entangled states, that is, the first sender first prepares M five-photon cluster states, and then the first sender retains each five-photon entangled state The first photon and the third photon of each five-photon entangled state, and then send the fourth photon of each five-photon entangled state to the second sender, and send the second photon and fifth photon of each five-photon entangled state to the receiver;

Step 2: The first sender and the second sender prepare two-photon state information as required, set the parameters of the polarization beam splitter, and perform measurements on the photons passing through the polarization beam splitter;

Step 3: According to the measurement results from the first sender and the second sender, the receiver chooses to perform local unitary evolution operations on the photons in his hands corresponding to the measurement results, and then rebuilds the quantum state to be prepared, thus completing Remote joint preparation of arbitrary two-photon states.

Further, in step 2, the parameters set are: the rotation angle of the polarization state of the photon by the glass slide R(θ ₁ ) in the optical path passed by the first photon of the first sender The third photon passes through the glass slide R(θ ₂ ) in the optical path to rotate the polarization state of the photon The fourth photon of the second sender passes through the glass slide R(θ ₃ )R(θ ₂ ) in the optical path to the rotation angle of the polarization state of the photon

Further, the first sender and the second sender send the measurement results to the receiver through the classical communication channel.

Further, in step 2, the first sender and the second sender perform orthogonal projection measurement on the photons passing through the polarization beam splitter.

The present invention has the following beneficial effects: the present invention can realize the remote joint preparation of any two-photon state by sharing a five-photon entangled state with two senders and one receiver, with high communication efficiency and strong feasibility, and the realization of the scheme can be achieved without The maximum entangled channel needs to be used, which greatly saves the cost of implementing the scheme and reduces the technical requirements of the implementing scheme.

detailed description

The method for remote joint preparation of arbitrary two-photon states based on linear optical elements of the present invention will be further described below in combination with embodiments.

There are three participants in the remote joint preparation method of arbitrary two-photon states based on linear optical elements in the present invention, including a first sender, a second sender and a receiver.

The first sender, the second sender, and the receiver share M five-photon entangled states, where the first sender is the producer of the five-photon entangled state, and the first sender owns the first photon of each five-photon entangled state and the third photon, the second sender has the fourth photon of each five-photon entanglement state, and the receiver has the second photon and the fifth photon of each five-photon entanglement state; suppose the quantum state to be prepared is |ψ>= α ₀₀ |00>+α ₀₁ |01>+α ₁₀ |10>+α ₁₁ |11>, where α ₀₀ , α ₀₁ , α ₁₀ , and α ₁₁ are any complex numbers that satisfy the normalization relation |α ₀₀ | ² +|α ₀₁ | ² +|α ₁₀ | ² +|α ₁₁ | ² = 1;

The concrete steps of described method are as follows:

Step 1: The first sender, the second sender, and the receiver share M five-photon entangled states, that is, the first sender first prepares M five-photon entangled states, and then the first sender retains each five-photon entangled state The first photon and the third photon of each five-photon entanglement state are sent to the second sender, and the second photon and the fifth photon of each five-photon entanglement state are sent to the receiver.

Step 2: The first sender and the second sender prepare the two-photon state information according to the needs, and set the parameters of the slide behind the polarization beam splitter, that is, the slide R(θ ₁ ) in the optical path through which the first photon of the first sender passes Rotation angle for photon polarization state The third photon passes through the glass slide R(θ ₂ ) in the optical path to rotate the polarization state of the photon The fourth photon of the second sender passes through the glass slide R(θ ₃ )R(θ ₂ ) in the optical path to the rotation angle of the polarization state of the photon The quantum entangled channel is transformed into the target channel, and the orthogonal projection measurement is performed on the entangled photons after passing through the polarization beam splitter. Compared with general measurement, the use of orthogonal projection measurement in this embodiment has the advantages of low requirements on equipment and easy implementation.

Step 3: The receiver receives the measurement results from the first sender and the second sender through the classical communication channel, and according to the measurement results, the particles in the hands of the receiver collapse to a state corresponding to the measurement results, and according to the relationship between the measurement results and the state of the remaining particles One-to-one correspondence between them, the receiver selects the local unitary evolution operation corresponding to the measurement result, and can reconstruct the original quantum state on its particles, thereby completing the remote joint preparation of any two-photon state.

In summary, the present invention can realize the remote joint preparation of any two-photon state by sharing a five-photon entangled state with two senders and one receiver. The communication efficiency is high and the feasibility is strong, and the realization of the scheme does not need The maximum entanglement channel greatly saves the cost of the implementation of the scheme and reduces the technical requirements of the implementation scheme.

Claims (3)

1. A kind of 1. any long-range combined preparation process of two-photon state based on linear optical element, it is characterised in that：Methods described Participant shares three, including first sender, second sender and a recipient；

   First sender, the second sender, recipient share M five photon entanglement states, wherein, the first sender is as five photons The preparation person of Entangled State, the first sender possess the first photon and three-photon of each five photon entanglements state, the second sender Possess the 4th photon of each five photon entanglements state, recipient possesses the second photon and the 5th light of each five photon entanglements state Son；

   Assuming that the quantum state that need to be prepared is | ψ>=α₀₀|00>+α₀₁|01>+α₁₀|10>+α₁₁|11>, wherein α₀₀,α₀₁,α₁₀,α₁₁For Any plural number, meets Normalized Relation | α₀₀|²+|α₀₁|²+|α₁₀|²+|α₁₁|²=1；

   Methods described comprises the following steps that：

   Step 1：First sender, the second sender, recipient share M five photon entanglement states, i.e. the first sender enters first Row prepares M five photon entanglement states, and then the first sender retains the first photon and three-photon of each five photon entanglements state, Secondly the 4th photon of each five photon entanglements state is sent to the second sender, the second photon by each five photon entanglements state Recipient is sent to the 5th photon；

   Step 2：First sender and the second sender set polarization beam splitter parameter according to that need to prepare two-photon state information, and To performing measurement by the photon after polarization beam splitter；Set each parameter be：First the first photon of sender passes through light path Middle slide R (θ₁) to the photon polarization state anglec of rotationThree-photon passes through slide R (θ in light path₂) inclined to photon The polarization state anglec of rotationThe photon of second sender the 4th passes through slide R (θ in light path₃)R(θ₂) to photon polarization state The anglec of rotation

   Step 3：Recipient selects the light in opponent according to the measurement result from the first sender and the second sender, recipient Son carries out local unitary evolution operation corresponding with measurement result, you can reconstruction need to prepare quantum state, so as to complete any double light Sub- state remotely combines preparation.
2. 2. any long-range combined preparation process of two-photon state based on linear optical element as claimed in claim 1, its feature It is：Measurement result is issued recipient by the first sender and the second sender by classical communication channel.
3. 3. any long-range combined preparation process of two-photon state based on linear optical element as claimed in claim 1, its feature It is：In step 2, the first sender and the second sender are that rectangular projection is surveyed to what is performed by the photon after polarization beam splitter Amount.