KR102032144B1 - Quantum system performing quantum channel estimation and method of modelling quantum channel - Google Patents

Abstract

In the method for performing quantum channel prediction according to the present invention, the method is performed by a first device, which is a transmitting device, and transmits a density operator ρ to a second device, which is a receiving device, through a quantum channel. State transfer, wherein the quantum channel is a time-correlated compressed generalized amplitude damping (SGAD) channel; A second receiving step of receiving status information from both the first device information based on the probability map (Φ (ρ)) received by the second device via the quantum channel; And a quantum channel estimating step of estimating the characteristics of the SGAD channel based on the information on the received probability map Φ ( ρ ), wherein the channel memory effect is quantized in a time-correlated quantum channel having a specific initial state. Qualitatively analyze the impact on correlations.

Description

Quantum system performing quantum channel estimation and method of modeling quantum channel

The present invention relates to a quantum system for performing quantum channel prediction. More particularly, the present invention relates to a quantum memory channel modeling method and a quantum channel prediction method and a quantum communication system for performing the same.

Advances in quantum technology are expected to have a significant impact on various information processing using the characteristics of quantum mechanics in cloud computing, 5G communication, and the Internet of Things. Quantum correlation, such as quantum entanglement and discrepancy, is importantly available for a variety of potential applications such as ultra compression coding, quantum teleportation, and quantum cryptography. However, there is a problem that quantum non-localities related to such quantum states can be easily vulnerable to interaction with the environment. That is, there is a problem that quantum non-locality can be easily weakened by quantum noise or decoherence. Therefore, studying quantum correlation behavior under various ambient noises, and generating and preserving quantum correlations are of great importance in the field of quantum information processing and quantum computation.

Meanwhile, channel memory effects have been widely utilized through various quantum channels. Channel memory effects caused by continuous channel use can increase the fundamental capacity of a quantum channel by using entangled quantum states rather than separable quantum states. Unlike information theory analysis, channel memory effects can freeze the quantum correlation evolution between two qubits over time. Thus, entanglement sudden death (ESD) can be completely avoided. In addition, quantum correlation may be generated or preserved over time-correlated quantum channels.

This channel memory effect has been experimentally demonstrated in fiber-optic links exhibiting fluctuating birefringence and in solid-state quantum hardware experiencing low frequency noise. Therefore, it is important to study the effect of channel memory on the dynamic behavior of various types of quantum correlation. For example, the effects of channel memory on quantum correlation dynamics in amplitude damping, phase distortion, depolarizing, and time-correlated Markovian quantum channels (TCMQCs) have been discussed. The role of early states on entanglement dynamics in non-inertial frames in amplitude distortion, non-polarization and bit flip channels has been studied. On the other hand, non-correlation can be effectively suppressed using the weak measurement (WM) proposed to protect quantum states from non-correlation.

However, there is a problem that a method for accurately analyzing the influence on the quantum correlation due to the channel memory effect described above has not been presented. In particular, there is a problem that the effect of the channel memory effect on the quantum correlation has not been qualitatively analyzed in the time-correlated quantum channel having a specific initial state. Thus, in quantum communication and security, accurate estimation of quantum channels over time is required.

Accordingly, an object of the present invention is to provide an accurate quantum channel estimation method according to a change in time.

In addition, an object of the present invention is to qualitatively analyze the effect of channel memory effects on quantum correlation in a time-correlated quantum channel having a specific initial state.

In the method for performing quantum channel prediction according to the present invention for solving the above problems, the method is performed by a first device that is a transmitting device, the second operator is a receiving device through the quantum channel density operator ( ρ ) Transmitting a first quantum state to a device, wherein the quantum channel is a time-correlated compressed generalized amplitude damping (SGAD) channel; A second receiving step of receiving status information from both the first device information based on the probability map (Φ (ρ)) received by the second device via the quantum channel; And a quantum channel estimating step of estimating the characteristics of the SGAD channel based on the information on the received probability map Φ ( ρ ), wherein the channel memory effect is quantized in a time-correlated quantum channel having a specific initial state. Qualitatively analyze the impact on correlations.

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map on a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k can be the Kraus operator in the time-correlated quantum channel. In this case, the quantum channel estimating step is characterized by estimating a channel memory parameter μ and a compression parameter m based on the information on the received probability map Φ ( ρ ).

In one embodiment, the quantum channel estimating step includes: obtaining concurrence information for a probability map for initial density matrices ρ ₁ and ρ ₂ ; And estimating the channel memory parameter μ and the compression parameter m based on the conference information at a specific time point, and estimating the quantum entanglement factor ε based on the conference information in the steady-state. A quantum channel factor estimation step may be included.

In one embodiment, the quantum channel estimating step includes: obtaining information about quantum discord for initial density matrices ρ ₁ and ρ ₂ ; And a quantum channel factor estimation for estimating the channel memory parameter μ and the compression parameter m based on the quantum mismatch information at a specific time point, and estimating the quantum entanglement factor ε based on the quantum mismatch information in the steady state. It may include a step.

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is unique It may be an eigenvalue. In the quantum channel estimating step, the eigen value is estimated to obtain a zero-temperature dissipation rate Ω, an average number n of photons, and a compression parameter m.

In an embodiment, the method may further include a channel parameter transferring step of transmitting the channel memory parameter μ and the compression parameter m to the second device based on the estimated SGAD channel. In this case, the second device may perform quantum communication with the first device based on the channel memory parameter μ and the compression parameter m.

In a method for performing quantum channel prediction according to another aspect of the present invention, the method is performed by a second device, which is a receiving device, and performs a density operator ρ transmitted over a quantum channel from a first device, which is a transmitting device. Receiving a First Quantum State Receiving—The Quantum Channel is a Time-correlated Compressed Generalized Amplitude Damping (SGAD) Channel, and the Density Operator ρ is a Probabilistic Map over the SGAD Channel. Received as Φ ( ρ ); And a quantum channel estimating step of estimating characteristics of the SGAD channel based on the received probability map Φ ( ρ ).

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map on a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k can be the Kraus operator in the time-correlated quantum channel. In this case, the quantum channel estimation step, based on the information on the received probability map (Φ ( ρ )), characterized in that for estimating the information about the channel memory parameter μ and compression parameter m.

In an embodiment, in the quantum channel estimating step, based on the conference information at a specific time, information about the channel memory parameter μ and the compression parameter m is estimated, and in steady-state Based on the conference information, information about the quantum entanglement factor ε estimated by the first device may be estimated. In this case, the conference information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

In one embodiment, in the quantum channel estimation step, based on the quantum mismatch information at a specific time, estimating information about the channel memory parameter μ and the compression parameter m, and based on the quantum mismatch information in the steady state, Information about the quantum entanglement factor ε can be estimated. In this case, the quantum mismatch information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is unique It may be an eigenvalue. In this case, in the quantum channel estimation step, information about a zero-temperature dissipation rate Ω, an average number n of photons and a compression parameter m may be estimated based on the eigenvalue.

A quantum transmitting device for performing quantum channel prediction according to another aspect of the present invention transmits a density operator ρ through a quantum channel to a second device, which is a receiving device, by the second device through the quantum channel. An interface unit for receiving information about the received probability map Φ ( ρ ) from the second device, the quantum channel being a time-correlated compressed generalized amplitude damping (SGAD) channel ―; And a controller estimating characteristics of the SGAD channel based on the received information about the probability map Φ ( ρ ).

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map on a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k can be the Kraus operator in the time-correlated quantum channel. In this case, the controller may estimate a channel memory parameter μ and a compression parameter m based on the received information about the probability map Φ ( ρ ).

In one embodiment, the control unit obtains concurrence information on the probability maps for the initial density matrices ρ ₁ and ρ ₂ , and compresses the channel memory parameter μ and compression based on the conference information at a specific time. A parameter m may be estimated and a quantum entanglement factor ε may be estimated based on the conference information in the steady-state.

In one embodiment, the control unit obtains information about quantum discord for the initial density matrices ρ ₁ and ρ ₂ , and based on the quantum discord information at a specific time, the channel memory parameter μ and the compression parameter The phosphorus m may be estimated, and based on the quantum mismatch information in the steady state, the quantum entanglement factor ε may be estimated.

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is unique It may be an eigenvalue. In this case, the controller may estimate the eigenvalues to obtain a zero-temperature dissipation rate Ω, an average number n of photons, and a compression parameter m.

In still another aspect of the present invention, a quantum receiving device for performing quantum channel prediction includes an interface unit for receiving a density operator ρ transmitted over a quantum channel from a first device, which is a transmitting device, wherein the quantum channel is time-. A time-correlated Compressed Generalized Amplitude Damping (SGAD) channel, wherein the density operator ρ is received as a probability map Φ ( ρ ) over the SGAD channel; And a controller estimating characteristics of the SGAD channel based on the received probability map Φ ( ρ ).

In one embodiment, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map on a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k can be the Kraus operator in the time-correlated quantum channel. In this case, the controller may estimate the information about the channel memory parameter μ and the compression parameter m based on the information about the received probability map Φ ( ρ ).

In an embodiment, the controller estimates information about the channel memory parameter μ and the compression parameter m based on the conference information at a specific time, and the conference information in a steady-state. Based on, information about the quantum entanglement factor ε estimated by the first device may be estimated. In this case, the conference information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

In one embodiment, the control unit estimates the information about the channel memory parameter μ and the compression parameter m based on the quantum mismatch information at a specific time, and based on the quantum mismatch information in the steady state, entanglement information can be estimated. In this case, the quantum mismatch information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

The method according to the present invention has an advantage in that it is possible to provide an accurate quantum channel estimation method according to the change of time by using the quantum correlation property of the quantum state.

In addition, the problem to be solved in the present invention, there is an advantage that can be analyzed qualitatively the effect of the channel memory effect on the quantum correlation in the time-correlated quantum channel having a specific initial state.

In particular, there is an advantage in that channel memory effects on quantum correlation behavior can be demonstrated using the Werner-like mixed state initially prepared in a time-correlated compressed general amplitude distortion (SGAD) channel.

1 illustrates a quantum system for performing a quantum channel prediction method according to the present invention.
2 shows a detailed configuration of a quantum device according to the present invention.
3a and 3b show the conferences for ρ ₁ and ρ ₂ according to the compression parameter m for μ = 0, 0.2, 0.4, 0.6, 0.8 and 1 according to the invention.
4A and 4B show conkers for n = 1, Ω = 1, ε = 0.6 as a function of time t for m = 0, 0.5, 1.0, and m → 1.5, for μ = 0 and μ = 0, respectively. Indicates a run.
5A and 5B are diagrams for showing the conference behavior of the initial state ρ ₂ in the steady state.
6a and 6b show at t = 0.5 as a function of the compression parameter m for n = 1, Ω = 1, ε = 0.9 for μ = 0, 0.2, 0.4, 0.6, 0.8, 1 according to the invention. Inconsistency in denaturation state.
7A and 7B show inconsistencies for n = 1, Ω = 1, ε = 0.6 as a function of time t for m = 0, 0.5, 1.0, and m → 1.5, for μ = 0 and μ = 0, respectively. Indicates.
8A and 8B show inconsistencies at steady state as a function of (ε, μ) for n = 0 and n → ∞.
9 is a flowchart of a quantum channel prediction method according to an embodiment of the present invention.
10 is a flowchart of a quantum channel prediction method according to another embodiment of the present invention.

The above-described features and effects of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, and thus, those skilled in the art to which the present invention pertains may easily implement the technical idea of the present invention. Could be. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosure, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

In describing each drawing, like reference numerals are used for like elements.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term “and / or” includes any combination of a plurality of related items or any item of a plurality of related items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art.

Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined herein. Should not.

The suffixes "module", "block", and "unit" for components used in the following description are given or mixed in consideration of ease of specification, and do not have distinct meanings or roles by themselves. .

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described to be easily carried out by those of ordinary skill in the art. In the following description of the embodiments of the present invention, when it is determined that the detailed description of the related known functions or known configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a quantum channel prediction method and a quantum channel prediction system according to the present invention will be described.

In this regard, FIG. 1 illustrates a quantum system for performing a quantum channel prediction method according to the present invention. As shown in FIG. 1, the quantum system may include a plurality of subsystems, and may be represented as including the first subsystem 100 and the second subsystem 200 for convenience. However, the present invention is not limited to the first and second subsystems 100 and 200 but may be applied between any number of subsystems. Meanwhile, the first and second subsystems 100 and 200 may be arbitrary quantum devices. That is, each of the first and second subsystems 100 and 200 may be a first (quantum) device that is a transmitting device and a second (quantum) device that is a receiving device. Meanwhile, the first (quantum) device 100 and the second (quantum) device 200 may be a receiving device if one device is a transmitting device. On the other hand, the case where the first (quantum) device 100 is a control station (or base station, server) for controlling the plurality of second (quantum) devices 200 is included.

2 shows a detailed configuration of a quantum device according to the present invention. For convenience, the transmitting device may be referred to as the first device 100 and the receiving device as the second device 200. However, the present invention is not limited thereto, and vice versa, as described above, and can simultaneously operate as a transmitting / receiving device.

The first device 100 includes a control unit 110, an interface unit 120, and a memory 130. Similarly, the second device 200 also includes a control unit 210, an interface unit 220, and a memory 230. Here, the interface units 120 and 220 may be referred to as quantum interface units because they transmit and receive quantum data through quantum channels. In addition, since the interface unit 120 or 220 may transmit / receive some control data or related information through a classic channel, it may also be referred to as a general interface unit. That is, the interface units 120 and 220 may include physically divided quantum interface units and general interface units, or logically divided quantum interface units and general interface units. Accordingly, the interface unit 120 is configured to transmit quantum information to the second device 200 which is a receiving device through a classic channel and a quantum channel. Here, quantum information includes information about a state (eg, quantum state). In addition, the interface unit 120 may receive feedback information (eg, quantum channel information and correlation feedback) from the second device 200 through the general channel.

The interface unit 120 transmits the first quantum state ρ to the second device 200 which is the receiving device through the quantum channel and the second quantum state received by the second device 200 through the quantum channel. Configured to receive information about φ ( ρ ) from the second device 200. In this case, the first quantum state ρ may be composed of N qubit sequences.

In detail, the interface unit 120 transmits the density operator ρ to the second device 200 which is the receiving device through the quantum channel, and the probability map Φ received by the second device 200 through the quantum channel. ( ρ )) is received from the second device 200. Herein, the quantum channel may be a time-correlated compressed general amplitude distortion (SGAD) channel.

The controller 110 is configured to estimate the characteristics of the SGAD channel based on the received information about the probability map Φ ( ρ ).

Memory 130 may be configured to store quantum information and general information with respect to quantum channel estimation and state transfer.

Next, an operation performed by the second device 200 corresponding to the receiving device will be described.

The interface unit 210 is configured to receive the first quantum state ρ from the first device 100, which is a transmitting device, through a quantum channel. In this case, the first quantum state ρ may be received in the second quantum state Φ ( ρ ) by the interface unit 210 through the quantum channel. In this case, the first quantum state ρ may be composed of N qubit sequences.

Specifically, the interface unit 210 receives the density operator ρ transmitted through the quantum channel from the first device 100, which is a transmitting device. Herein, the quantum channel may be a time-correlated compressed general amplitude distortion (SGAD) channel. In this case, the density operator ρ may be received as a probability map Φ ( ρ ) by the interface unit 210 through the quantum channel.

On the other hand, the quantum information transmitted by the first device 100 may be a known training sequence known by the second device 200 or unknown quantum data.

The controller 220 may be configured to estimate a characteristic of the SGAD channel based on the received probability map Φ ( ρ ). In this regard, quantum channel estimation may be performed by the controller 120 of the first device 100 as described above, but may be performed by the controller 220 of the second device 200. According to an embodiment of the present disclosure, when the N qubit sequences are known training sequences known by the second device 200, the quantum channel estimation is performed by the controller 220 of the second device 200. This can be done. In addition, even if the N qubit sequences are unknown quantum data, the control unit 220 may perform quantum channel estimation using the state information and the blind estimation method from the first device 100. .

Memory 130 may be configured to store quantum information and general information with respect to quantum channel estimation and state transfer.

Meanwhile, with respect to the quantum channel prediction system described above, a series of procedures according to the present invention related to specific operations in a quantum transmitting / receiving device will be described in detail as follows. In this regard, let's look at the Squeezed Generalized Amplitude Damping (SGAD) channel .

In an open system, the stochastic map of the density operator ρ undergoes a transformation process as shown in Equation 1 below.

Here, it may be assumed that the density operator satisfies the master equation of Equation 2.

는 Lindblad 연산자, 및 [·,·]는 교환자(commutator)를 나타낸다. 첫번째 부분은 코히어런트 다이내믹스를 설명하고, 두번째 부분은 왜곡 메커니즘을 설명한다. Born-Markov 회전파(rotating wave) 근사화 하에서 압축 열 상태(squeezed thermal state)로 초기에 배스(bath)와 상호 작용하는 양자 시스템의 SGAD 채널에 대하여, SGAD 채널에 대응하는 Lindblad 연산자는 수학식 3과 같은 형태를 갖는다.Where H is the system Hamiltonian,

Denotes a Lindblad operator, and [·, ·] denotes a commutator. The first part describes coherent dynamics and the second part explains the distortion mechanism. For SGAD channels in quantum systems that initially interact with the bath in a compressed thermal state under Born-Markov rotating wave approximation, the Lindblad operator corresponding to the SGAD channel is Have the same form.

및

는 생성(creation) 및 소멸 (annihilation) 연산자; i = 1, 2, 3 에 대하여 σ_i는 파울리(Pauli) 행렬; n은 열 광자(thermal photon)의 개수; m < n + 1/2는 압축 파라미터; Ω는 자발 방출(spontaneous emission)과 연관된, 원자 다이폴의 zero-temperature dissipation rate를 나타낸다. 압축 파라미터는 원자 다이폴의 비균등 왜곡율을 유도한다. 즉, 원자 다이폴의 동위상(in-phase)과 비-동위상(out-phase)은 다른 방식으로 영향을 미치며, 이는 압축 파라미터 m에 의해 정량화될 수 있다. SGAD 채널은 m = 0 인 경우 일반 진폭 왜곡(amplitude damping) 채널 (열장(thermal field) 채널)과 등가이고, n = 0으로 설정하여 진폭 왜곡 채널 (자발 방출)로 더 단순화될 수 있다.here,

And

Is a creation and annihilation operator; σ _i is a Pauli matrix for i = 1, 2, 3; n is the number of thermal photons; m <n + 1/2 is the compression parameter; Ω represents the zero-temperature dissipation rate of the atomic dipole, associated with spontaneous emission. Compression parameters lead to non-uniform distortion of atomic dipoles. That is, the in-phase and out-phase of the atomic dipoles affect the other way, which can be quantified by the compression parameter m. The SGAD channel is equivalent to a normal amplitude damping channel (thermal field channel) when m = 0, and can be further simplified to an amplitude distortion channel (spontaneous emission) by setting n = 0.

 Time-Correlated Quantum Channel

The quantum channel guarantees a completely positive and trace preserving (CTPP) characteristic. The probability map Φ ( ρ ) of the density operator ρ in the quantum channel may be expressed as Equation 4.

는 크라우스 연산자이고

은 N 큐빗의 시퀀스에 적용되는 연산자의 랜덤 시퀀스에 대한 확률이고

을 만족한다. 연속적인 채널 사용을 위한 메모리 효과에 대한 수학식과 관련하여,

은 수학식 5와 같은 형태를 갖는다.here,

Is the Kraus operator

Is the probability of a random sequence of operators applied to a sequence of N qubits

To satisfy. Regarding the equation for the memory effect for continuous channel use,

Has the form as shown in equation (5).

은 조건부 확률이고, 예를 들어 두 번의 연속적인 채널 사용 간에 시간 상관이 존재하는 양자 채널을 고려할 수 있다. 이때, 채널 메모리 파라미터의 척도인 μ∈ [0, 1]를 도입하여, 수학식 5의 조건부 확률은

로 단순화될 수 있고, 이로부터 수학식 6과 같이 양자 메모리 채널에 대한 크라우스 연산자를 획득할 수 있다.here,

Is a conditional probability, for example consider a quantum channel where there is a time correlation between two consecutive channel uses. At this time, μ∈ [0, 1], which is a measure of the channel memory parameter, is introduced, and the conditional probability of Equation 5 is

It can be simplified to, and from this it is possible to obtain the Kraus operator for the quantum memory channel as shown in equation (6).

Here, δ i, j represents a Kronecker delta defined by Equation 7.

을 갖는 두 개의 큐빗에 대한 확률 맵 Φ과 임의의 채널 메모리에 대한 명시적 표현은 수학식 8과 같이 표현된다.Initial state

The probability map φ for two qubits with and the explicit representation for any channel memory are expressed as in Equation (8).

는 시간-상관 양자 채널에 대한 크라우스 연산자이다. here,

Is the Kraus operator for the time-correlated quantum channel.

Dynamics of Quantum Correlation

In general, quantum correlations can be divided into two categories: entanglement and discrepancy. The measurement of quantum correlation must satisfy the conditions of zero values for local unitary operations: i) non-negativity, ii) invariant, and iii) separable state. . Below we discuss quantum correlation dynamics using concurrence and discrepancy measurements in a time-correlated SGAD channel with an initial Werner-like mixed state.

Initial State

을 고려하면 수학식 9와 같이 표현 가능하다.Werner-like mixed state as initial state for two qubits

Considering this, it can be expressed as Equation 9.

Here, ε∈ [0, 1] represents the purity of the initial state, and two qubit states can be expressed as Equations 10 and 11, which correspond to two qubit states of bell-like entanglement.

The Werner-like state ρ _w is entangled if ε> 1/3, otherwise it is separable. In particular, ρ ₂ may be referred to as a singlet-like state.

로 표시되는 컨커런스는 수학식 12와 같이 연산될 수 있다.For an arbitrary density matrix for two qubit states,

The conference represented by may be calculated as shown in Equation 12.

는 확률 맵

의 내림 차순 형태의 고유값(eignevalue)이고, [x]+는 [x]+ = max{x, 0}이 되도록 x의 양수 부분을 나타낸다.here,

Probability map

Is an eigenvalue in descending order, and [x] + represents a positive portion of x such that [x] + = max {x, 0}.

의 출력은 수학식 13으로 표현 가능하다.Probability map for initial density matrix ρ ₁

The output of can be expressed by Equation 13.

Here, each factor of Equation 13 may be expressed as Equations 14 and 15.

로 표현된다. 유사하게, 초기 밀도 행렬 ρ ₂ 에 대하여 확률밀도의 출력은 수학식 16과 같이 표현된다.Where the distortion parameter is

It is expressed as Similarly, the output of the probability density for the initial density matrix ρ ₂ is expressed as

Here, each factor of Equation 16 may be represented by Equations 17 to 20.

On the other hand, for a complete memory channel (μ = 1), the conference for the two initial density matrices ρ ₁ and ρ ₂ can be expressed as Equations 21 and 22.

는 시간 t에 따라 단조 감소하고 결국 ESD 현상을 갖는다. 왜곡 감쇠 비율은 광자(photon)의 평균 개수 n 및/또는 압축 파라미터(squeezing parameter) m에 따라 증가하기 때문에, SGAD 채널에서 ESD 현상은 (일반화된) 진폭 왜곡 채널에서보다 더 빠른 것처럼 보인다. ρ ₂ 가 초기 상태로 준비된 경우 압축효과는 얽힘과 연관된 역학에 영향을 미치지 않는다.Conference of Equation 21

Decreases monotonically with time t and eventually has an ESD phenomenon. Since the distortion attenuation ratio increases with the average number n of photons and / or the squeezing parameter m, the ESD phenomenon in the SGAD channel appears to be faster than in the (generalized) amplitude distortion channel. When ρ ₂ is prepared in its initial state, the compressive effect does not affect the kinetics associated with the entanglement.

In steady state (t → k), two initial density matrices ρ ₁ and ρ ₂ are represented by equations 23 and 24.

임을 주목할 필요가 있다. 포지티브 값의 채널 메모리 값을 갖는 채널 메모리 자발 방출 (n = 0)의 경우에, 상태 ρ ₂ 에서의 얽힘은 수학식 25와 같이 결국 비-제로 컨커런스를 갖는다.This means that the entanglement in state ρ ₁ disappears over time regardless of the quantum channel parameter, whereas the entanglement in state ρ ₂ may be preserved or may occur depending on the quantum channel parameter. Entangling in pure state ρ ₂ with complete channel memory (μ = ε = 1) does not change over time, i.e.

It should be noted that In the case of channel memory spontaneous emission (n = 0) with a channel memory value of positive value, the entanglement in state ρ ₂ eventually has a non-zero conference, as in equation (25).

는 수학식 26과 같이 수렴됨을 알 수 있다.This means that entanglement may occur in the steady state by the channel memory even though the initial state is prepared in the non-entangled state (ε ≦ 1/3). n → according to ,, conference

It can be seen that is converged as in Equation 26.

In this regard, it can be seen that the state ρ ₂ has a non-zero conference only if εμ ≧ 1/3.

3a and 3b show the conferences for ρ ₁ and ρ ₂ according to the compression parameter m for μ = 0, 0.2, 0.4, 0.6, 0.8 and 1 according to the invention. 3A and 3B, n = 1, Ω = 1, ε = 0.9. 3A and 3B, it can be seen that as mu increases, a higher conference can be obtained due to the strong channel memory effect. In the case of 0 ≦ μ ≦ 1, it can be seen that the strong compression effect on the state ρ ₂ strengthens the entanglement phenomenon. On the other hand, it can be seen that the high channel memory effect on the state ρ ₁ degrades the entanglement phenomenon. This is due to a component effect called cosh (2Ωmt), which is associated with the compression parameter and can be seen to degrade as the channel memory increases for the conference.

를 갖는 얽힘 상태를 갖는다. 도 4a에 도시된 바와 같이, 컨커런스는 빠르게 감소하고, ESD 현상은 채널 메모리가 없는 것처럼 보인다.

와 비교하여

는 약간 더 큰 컨커런스 값을 가지고, 압축 효과는 ESD 현상을 지연시킴을 알 수 있다. ESD 현상이 상태 ρ ₁ 에서 채널 메모리에 의해 연기될 수 있지만, ESD 현상은 도 4b와 같이 회피할 수는 없다. 그러나, 얽힘 상태는 보존될 수 있고, 상태 ρ ₂ 에서 채널 메모리 효과에 의해 ESD 현상을 완전히 회피할 수 있다. 이러한 예에서,

이고, 이는 수학식 24에 표시된 정상 상태의 컨커런스에 대응한다. 도 3a 및 도 3b에 도시된 바와 같이, 초기 상태 ρ ₂ 에서 시간에 따른 컨커런스의 왜곡은 압축 파라미터 m에 의해 지연된다. 반면에, 높은 채널 메모리에 기인하는 초기 상태 ρ ₁ 에서 시간에 따른 컨커런스의 감쇠는 압축 파라미터 m이 증가함에 따라 강화된다. 4A and 4B show conkers for n = 1, Ω = 1, ε = 0.6 as a function of time t for m = 0, 0.5, 1.0, and m → 1.5 for μ = 0 and μ = 0, respectively. Indicates a run. Initially, in every initial state, two qubits

Having a tangle state. As shown in FIG. 4A, the conference is rapidly decreasing, and the ESD phenomenon appears to be without channel memory.

In comparison with

Has a slightly larger conference value, and the compression effect delays the ESD phenomenon. Although the ESD phenomenon may be delayed by the channel memory in state ρ ₁ , the ESD phenomenon cannot be avoided as shown in FIG. 4B. However, the entanglement state can be preserved and the ESD phenomenon can be completely avoided by the channel memory effect in state ρ ₂ . In this example,

, Which corresponds to the steady-state conference shown in equation (24). As shown in FIGS. 3A and 3B, the distortion of the conference over time in the initial state ρ ₂ is delayed by the compression parameter m. On the other hand, the attenuation of the conference over time in the initial state ρ ₁ due to the high channel memory is enhanced as the compression parameter m increases.

를 도시한 것이다. n = 0 (자발 방출)의 경우, 초기에 두 개의 큐빗 사이에 얽힘이 없는 경우 (ε < 1/3)에도 포지티브 채널 메모리가 존재한다면 시간-상관 SGAD 채널을 통과한 이후에 두 개의 큐빗 사이에 얽힘이 발생할 수 있다. 그러나, n이 증가함에 따라 이러한 얽힘 발생 현상은 억제된다. 도 5b 및 수학식 26에 나타난 바와 같이, εμ < 1/3이면 상태 ρ ₂ 는 결국 비-얽힘(disentanglement) 상태가 된다. 다시 말하면, 초기에 준비된 혼합 상태 ρ ₂ 가 얽힘이 없는 경우 (ε < 1/3), 양자 채널이 완전한 채널 메모리를 갖는 경우라도 얽힘 현상이 발생하지 않게 된다. 정상 상태에서 얽힘에 대한 n의 효과는 n = 0인 경우 원자 변환 접근 방식(atomic inversion approaches)으로부터 발생되는 반면에, n ≠ 0인 경우 특정 포지티브 평형(equilibrium)에 접근한다.5A and 5B are diagrams for showing the conference behavior of the initial state ρ ₂ in the steady state. Figures 5a and 5b show the convection as a function of (a, n) with (a) the best case n = 0 (amplitude distortion channel) and (b) the worst case with n → ∞

It is shown. For n = 0 (spontaneous emission), if there is still a positive channel memory even when there is no entanglement between the two qubits (ε <1/3), then between two qubits after passing through the time-correlated SGAD channel Entangling may occur. However, as n increases, this phenomenon of entanglement is suppressed. As shown in FIG. 5B and Equation 26, if εμ <1/3, the state ρ ₂ eventually becomes a disentanglement state. In other words, when the initially prepared mixed state ρ ₂ is free of entanglement (ε <1/3), no entanglement occurs even if the quantum channel has a complete channel memory. The effect of n on entanglement at steady state arises from atomic inversion approaches when n = 0, whereas n ≠ 0 approaches a specific positive equilibrium.

Quantum Discord

Operations for inconsistencies fall into the category of NR-complete. However, it is possible to determine discrepancies analytically for certain quantum states. For example, the 'X' state p is defined by equation (27).

An analytic representation of the inconsistency with respect to state ρ can be calculated as shown in Equation 28.

Here, Q ₁ and Q ₂ can be represented by equations (29) and (30).

는 ρ의 i번째 고유값이다.here,

Is the i th eigenvalue of ρ .

The inconsistency of the initial state ρ _W has a positive value and may be calculated as in Equation 31 for 0 <ε <1.

이다.On the other hand, for ε = 1

to be.

In the steady state, the contaminated state can be expressed as in Equations 32 and 33.

Since the density matrix in the steady state has only a diagonal component (thus Q ₂ = 0), the quantum state ρ ₁ can prove that the disparity value eventually becomes zero. It can be seen that the quantum state ρ ₁ loses a quantum state that can be quantified by the non-diagonal component of the density matrix. On the other hand, the quantum state ρ ₂ maintains a mismatch in the presence of a positive channel memory even in the normal state, and the non-diagonal component of the density matrix becomes a function of μ.

6a and 6b show at t = 0.5 as a function of the compression parameter m for n = 1, Ω = 1, ε = 0.9 for μ = 0, 0.2, 0.4, 0.6, 0.8, 1 according to the invention. Inconsistency in denaturation state. It can be seen that the degree of inconsistency is generally higher than the conference. This is due to the more robust mismatch than entanglement in dissipative environments.

)는 모든 초기 상태에 대해 비-메모리(memoryless) 양자 채널에서 시간이 경과함에 따라 0으로 감쇠되거나, 초기 상태 ρ ₂ 에 대하여 채널 메모리가 보존되는 경우 비-제로 불일치 한계 영역에 접근한다. 이와 관련하여,

이다. 한편, 도 8a 및 도 8b는 n = 0 및 n →∞에 대하여 (ε, μ)의 함수로서 정상 상태에서 불일치를 나타낸다. 도 8a 및 도 8b을 참조하면, 도 4a 및 도 4b와 같이 불일치에 있어 동일한 거동, 즉 정상 상태에서의 불일치는 모두 초기 상태에 대한 ε 및 μ에 따라 증가함을 알 수 있다.7A and 7B show n = 1, Ω = 1, ε = 0.6 as a function of time t for m = 0, 0.5, 1.0, and m → 1.5 for μ = 0 and μ = 0.7, respectively. Inconsistency. It should be noted that there is no quantum correlation sudden death in the finite time domain. Mismatch (the initial mismatch

) Attenuates to zero over time in a memoryless quantum channel for all initial states, or approaches a non-zero mismatch limit region if channel memory is preserved for an initial state ρ ₂ . In this regard,

to be. 8A and 8B, on the other hand, show inconsistencies in steady state as a function of (ε, μ) for n = 0 and n → ∞. 8A and 8B, it can be seen that as shown in FIGS. 4A and 4B, the same behavior in the inconsistency, that is, the inconsistency in the steady state increases with ε and μ for the initial state.

Meanwhile, a probability map of time-correlated SGAD channels according to another embodiment of the present invention will be described below. In this regard, a modified version of Lindblad can be used to obtain a probability map as shown in Equation 34.

이다. Lindblad에 대한 솔루션은 임의의 시간에서 밀도 연산자 ρ를 확장시키는 고유값 방정식을 푸는 것과 연관된다.here,

to be. The solution for Lindblad involves solving eigenvalue equations that extend the density operator ρ at any time.

Where Li and Ri represent left and right eigenoperators, λ i corresponds to the eigenvalues, and tr (·) represents the trace operator. On the other hand, the eigenvalue λ i in Equation 35 is given by Equation 36.

The left and right unique operators described above can be represented by the following equations 37 to 46.

According to the duality relationship between Li and Rj, tr ( LiRj ) = δi , j is satisfied.

Probability map for state X: The density matrix ρ has the form

와

이다. 확률 맵

는 수학식 48으로 표현 가능하다.As an initial state

Wow

to be. Probability map

Can be expressed by Equation 48.

의 성분은 수학식 49로 표현 가능하다.here,

The component of can be expressed by Equation 49.

이다. 확률 맵

은 수학식 50으로 표현 가능하다.Where the attenuation parameter is

to be. Probability map

Can be expressed by Equation 50.

의 각 성분은 아래의 수학식 51 내지 56으로 표현 가능하다.here,

Each component of can be expressed by the following equations (51) to (56).

In the above, the quantum channel prediction method and the quantum transmission system performing the same according to the present invention have been described. Meanwhile, with reference to the quantum channel prediction method described above, it will be described with reference to the detailed configuration of the quantum system of FIG.

Referring to FIG. 2, the interface unit 120 transmits a first quantum state ρ to a second device 200 which is a receiving device through a quantum channel and is received by the second device 200 through a quantum channel. And receive information about the second quantum state Φ ( ρ ) from the second device 200. In this case, the first quantum state ρ may be composed of N qubit sequences.

In detail, the interface unit 120 transmits the density operator ρ to the second device 200 which is the receiving device through the quantum channel, and the probability map Φ received by the second device 200 through the quantum channel. ( ρ )) is received from the second device 200. Here, the quantum channel may be a time-correlated compressed general amplitude amplitude (SGAD) channel.

The controller 110 is configured to estimate the characteristics of the SGAD channel based on the received information about the probability map Φ ( ρ ).

Meanwhile, the probability map Φ ( ρ ) is determined by Equation 8, where φ _u ( ρ ) is a probability map in a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ Is the probability map in the time-correlated quantum channel, and B _k is the Kraus operator in the time-correlated quantum channel. In this case, the controller 110 may estimate the channel memory parameter μ and the compression parameter m based on the received information about the probability map Φ ( ρ ).

On the other hand, the controller 110 may obtain concurrence information on the probability maps for the initial density matrices ρ ₁ and ρ ₂ . In addition, the controller 110 may estimate the channel memory parameter μ and the compression parameter m based on the conference information at a specific time. In addition, the controller 110 may estimate the quantum entanglement factor ε based on the conference information in the steady-state.

Meanwhile, the controller 110 may obtain information about quantum discord of the initial density matrices ρ ₁ and ρ ₂ . In addition, the controller 110 may estimate the channel memory parameter μ and the compression parameter m based on quantum mismatch information at a specific time. In addition, the controller 110 may estimate the quantum entanglement factor ε based on the quantum mismatch information in the steady state.

Meanwhile, the probability map Φ ( ρ ) may be determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is an eigenvalue. )to be. In this case, the controller 110 may obtain a zero-temperature dissipation rate Ω, an average number n of photons, and a compression parameter m by estimating an intrinsic value.

Memory 130 may be configured to store quantum information and general information with respect to quantum channel estimation and state transfer.

Next, an operation performed by the second device 200 corresponding to the receiving device will be described.

The interface unit 210 is configured to receive the first quantum state ρ from the first device 100, which is a transmitting device, through a quantum channel. In this case, the first quantum state ρ may be received in the second quantum state Φ ( ρ ) by the interface unit 210 through the quantum channel. In this case, the first quantum state ρ may be composed of N qubit sequences.

Specifically, the interface unit 210 receives the density operator ρ transmitted through the quantum channel from the first device 100, which is a transmitting device. Herein, the quantum channel may be a time-correlated compressed general amplitude distortion (SGAD) channel. In this case, the density operator ρ may be received as a probability map Φ ( ρ ) by the interface unit 210 through the quantum channel.

On the other hand, the quantum information transmitted by the first device 100 may be a known training sequence known by the second device 200 or unknown quantum data.

The controller 220 may be configured to estimate a characteristic of the SGAD channel based on the received probability map Φ ( ρ ). In this regard, quantum channel estimation may be performed by the controller 120 of the first device 100 as described above, but may be performed by the controller 220 of the second device 200. According to an embodiment of the present disclosure, when the N qubit sequences are known training sequences known by the second device 200, the quantum channel estimation is performed by the controller 220 of the second device 200. This can be done. In addition, even if the N qubit sequences are unknown quantum data, the control unit 220 may perform quantum channel estimation using the state information and the blind estimation method from the first device 100. .

Further, the probability map Φ ( ρ ) is determined by Equation 8, where φ _u ( ρ ) is the probability map in the quantum channel, A _i is the Kraus operator, Φ _c ( ρ ) Is the probability map in the time-correlated quantum channel and B _k is the Kraus operator in the time-correlated quantum channel. In this case, the controller 220 may estimate the information about the channel memory parameter μ and the compression parameter m based on the received information about the probability map Φ ( ρ ).

Meanwhile, the controller 220 may estimate the information about the channel memory parameter μ and the compression parameter m based on the conference information at a specific time. In addition, the controller 220 may estimate the information on the quantum entanglement factor ε estimated by the first device based on the conference information in the steady-state. In this case, the conference information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

The controller 220 may estimate the information about the channel memory parameter μ and the compression parameter m based on the quantum mismatch information at a specific time. In addition, the controller 220 may estimate the information about the quantum entanglement factor ε based on the quantum mismatch information in the steady state. In this case, the quantum mismatch information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

Memory 130 may be configured to store quantum information and general information with respect to quantum channel estimation and state transfer.

In the above, the quantum transmission device and the quantum reception device for performing quantum channel prediction according to the present invention have been described. Meanwhile, the quantum channel prediction method described above is a quantum transmission device. It may be performed by a quantum receiving device as well as a server controlling them.

Hereinafter, a method of performing quantum channel prediction according to another aspect of the present invention will be described. In this regard, the foregoing description of the present invention may be combined with the method of performing quantum channel prediction described below.

9 is a flowchart illustrating a quantum channel prediction method according to an embodiment of the present invention. Each step of FIG. 9 may be performed by a quantum transmitting device or a quantum server.

Referring to FIG. 9, the quantum channel prediction method includes a first quantum state transmission step S110, a second quantum state information reception step S120, and a quantum channel estimation step S130. In addition, the quantum channel prediction method may further include a channel parameter transfer step (S140).

In a first quantum state transmission step S110, a density operator ρ is transmitted to a second device, which is a receiving device, through a quantum channel. In this case, the quantum channel may be a time-correlated compressed general amplitude damping (SGAD) channel.

In a step of receiving second quantum state information (S120), information on a probability map Φ ( ρ ) received by the second device through the quantum channel is received from the second device.

In the quantum channel estimation step S130, the characteristics of the SGAD channel may be estimated based on the received information about the probability map Φ ( ρ ). In this case, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map in a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) Is the probability map in the time-correlated quantum channel, and B _k is the Kraus operator in the time-correlated quantum channel. In this case, in the quantum channel estimation step S130, the channel memory parameter μ and the compression parameter m may be estimated based on the received information about the probability map Φ ( ρ ).

In the meantime, the quantum channel estimation step S130 may include obtaining concurrence information on a probability map of initial density matrices ρ ₁ and ρ ₂ ; And estimating the channel memory parameter μ and the compression parameter m based on the conference information at a specific time point, and estimating the quantum entanglement factor ε based on the conference information in the steady-state. A quantum channel factor estimation step may be included.

On the other hand, the quantum channel estimation step (S130) comprises the steps of obtaining information about quantum discord with respect to the initial density matrix ρ ₁ and ρ ₂ ; And a quantum channel factor estimation for estimating the channel memory parameter μ and the compression parameter m based on the quantum mismatch information at a specific time point, and estimating the quantum entanglement factor ε based on the quantum mismatch information in the steady state. It may include a step.

Meanwhile, the probability map Φ ( ρ ) is determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is an eigenvalue. to be. In this case, in the quantum channel estimation step S130, the eigen value may be estimated to obtain a zero-temperature dissipation rate Ω, an average number n of photons, and a compression parameter m.

Meanwhile, in the channel parameter transferring step (S140), the channel memory parameter μ and the compression parameter m may be delivered to the second device based on the estimated SGAD channel. In this case, the second device may perform quantum communication with the first device based on the channel memory parameter μ and the compression parameter m.

10 is a flowchart of a quantum channel prediction method according to another embodiment of the present invention. Each step of FIG. 10 may be performed by a quantum receiving device or a quantum device. The quantum channel prediction method of FIG. 10 is performed by a second device, which is a quantum reception device, and includes a first quantum state reception step S210, a quantum channel estimation step S220, and a channel parameter reception step 230.

In a first quantum state receiving step S210, a density operator ρ transmitted through a quantum channel is received from a first device, which is a transmitting device. In this case, the quantum channel is a time-correlated compressed general amplitude damping (SGAD) channel, and the density operator ρ is a probability map Φ ( ρ ) through the SGAD channel. Can be received.

In the quantum channel estimation step S220, the characteristics of the SGAD channel are estimated based on the received probability map Φ ( ρ ). In this case, the probability map Φ ( ρ ) is determined by Equation 8, where Φ _u ( ρ ) is a probability map in a quantum channel, A _i is a Kraus operator, and Φ _c ( ρ ) Is the probability map in the time-correlated quantum channel, and B _k is the Kraus operator in the time-correlated quantum channel. In this case, in the quantum channel estimation step S220, the information about the channel memory parameter μ and the compression parameter m may be estimated based on the received information about the probability map Φ ( ρ ).

On the other hand, in the quantum channel estimation step (S220), on the basis of the conference information at a specific time, information about the channel memory parameter μ and the compression parameter m is estimated, and in steady-state Based on the conference information, information about the quantum entanglement factor ε estimated by the first device may be estimated. In this case, the conference information may be obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

On the other hand, in the quantum channel estimation step (S220), based on the quantum mismatch information at a specific time, information about the channel memory parameter μ and the compression parameter m is estimated, and based on the quantum mismatch information in the steady state Information about the quantum entanglement factor ε can be estimated. In this case, the quantum mismatch information is the initial density matrix ρ ₁ And a probability map for ρ ₂ .

Meanwhile, the probability map Φ ( ρ ) is determined by Equation 35, wherein Li and Ri are left eigenoperator and right eigenoperator, and λ i is an eigenvalue. Can be. In this case, in the quantum channel estimation step S220, based on the eigenvalues, information about a zero-temperature dissipation rate Ω, an average number n of photons and a compression parameter m may be estimated.

In the channel parameter receiving step 230, based on the estimated SGAD channel, the channel memory parameter μ and the compression parameter m may be received from the first device. In this case, the second device may perform quantum communication with the first device based on the channel memory parameter μ and the compression parameter m.

In the above, quantum mechanics, ie entanglement and mismatch in time-correlated SGAD channels, have been discussed. Analytical representations of conferences and inconsistencies for compression parameters and channel memory may be provided. In this regard it can be summarized as follows: i) The singlet-like state is prepared as an initial state, entanglement and inconsistency can be preserved, and quantum correlation sudden death phenomenon is avoidable. ii) Even if the initial state is a non-entangled state, the initially prepared singlet-like state also enables entanglement phenomenon depending on the positive degree of the channel memory in the finite n regions. iii) The compression effect increases or delays quantum correlation, allowing it to be attenuated to equilibrium (which limits the steady-state value) as well as the initially prepared quantum state as well as channel memory degree.

The method according to the present invention has an advantage in that it is possible to provide an accurate quantum channel estimation method according to the change of time by using the quantum correlation property of the quantum state.

The method according to the present invention, therefore, aims to provide an accurate quantum channel estimation method over time.

In addition, the problem to be solved in the present invention, there is an advantage that can be analyzed qualitatively the effect of the channel memory effect on the quantum correlation in the time-correlated quantum channel having a specific initial state.

In particular, there is an advantage in that channel memory effects on quantum correlation behavior can be demonstrated using the Werner-like mixed state initially prepared in a time-correlated compressed general amplitude distortion (SGAD) channel.

According to the software implementation, each component as well as the procedures and functions described herein may be implemented as separate software modules. Each of the software modules may perform one or more functions and operations described herein. Software code may be implemented in software applications written in a suitable programming language. The software code may be stored in a memory and executed by a controller or a processor.

100: first subsystem 200: second subsystem
110, 210: control unit 120, 220: interface unit
130, 230: memory

Claims (20)

In the method for performing quantum channel prediction, the method is performed by a first device that is a transmitting device,
A first quantum state transmission step of transmitting a density operator ( ρ ) over a quantum channel to a second device, the receiving device, wherein the quantum channel is time-correlated compressed Sequentialized Amplitude Damping (SGAD). Channel;
A second receiving step of receiving status information from both the first device information based on the probability map (Φ (ρ)) received by the second device via the quantum channel; And
And a quantum channel estimating step of estimating a characteristic of the SGAD channel based on the information on the received probability map Φ ( ρ ). The method of claim 1,
The probability map Φ ( ρ ) is

Determined by
Where φ _u ( ρ ) is the probability map in the quantum channel, A _i is the Kraus operator, Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k is time-correlated Kraus operator on the quantum channel
The quantum channel estimation step,
And estimating a channel memory parameter [mu] and a compression parameter m, based on the information on the received probability map [phi] ([ rho ]). The method of claim 2,
The quantum channel estimation step,
Obtaining concurrence information for the probability maps for the initial density matrices ρ ₁ and ρ ₂ ; And
Based on the conference information at a specific time, the channel memory parameter μ and the compression parameter m are estimated,
And a quantum channel factor estimating step of estimating a quantum entanglement factor ε based on the conference information in a steady-state. The method of claim 2,
The quantum channel estimation step,
Obtaining information about quantum discord for initial density matrices ρ ₁ and ρ ₂ ; And
Based on the quantum mismatch information at a specific time, the channel memory parameter μ and the compression parameter m are estimated,
And a quantum channel factor estimating step of estimating a quantum entanglement factor ε based on the quantum mismatch information in the steady state. According to claim 1,
The probability map Φ ( ρ ) is

Determined by
Where Li and Ri are left eigenoperator and right eigenoperator, λ i is an eigenvalue,
The quantum channel estimation step,
And estimating the eigenvalue to obtain a zero-temperature dissipation rate Ω, an average number n of photons, and a compression parameter m. The method of claim 2,
Based on the estimated SGAD channel, further comprising a channel parameter transferring step of delivering the channel memory parameter μ and the compression parameter m to the second device,
And the second device performs quantum communication with the first device based on the channel memory parameter μ and the compression parameter m. In the method for performing quantum channel prediction, the method is performed by a second device that is a receiving device,
Receiving a first quantum state receiving a density operator ( ρ ) transmitted over a quantum channel from a first device that is a transmitting device, wherein the quantum channel is time-correlated compressed general amplitude attenuation (SGAD). Damping) channel, wherein the density operator [ rho ] is received as a probability map [phi ([ rho ]) over the SGAD channel; And
And a quantum channel estimating step of estimating a characteristic of the SGAD channel based on the received probability map Φ ( ρ ). The method of claim 7, wherein
The probability map Φ ( ρ ) is

Determined by
Where φ _u ( ρ ) is the probability map in the quantum channel, A _i is the Kraus operator, Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k is time-correlated Kraus operator on the quantum channel
The quantum channel estimation step,
And estimating information on a channel memory parameter [mu] and a compression parameter m, based on the information on the received probability map [phi] ([ rho ]). The method of claim 8,
In the quantum channel estimation step,
Estimate information about the channel memory parameter μ and the compression parameter m based on the conference information at a specific time,
Estimating information on the quantum entanglement factor ε estimated by the first device based on the conference information in a steady-state,
Wherein the conference information is obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ . The method of claim 8,
In the quantum channel estimation step,
Based on the quantum mismatch information at a specific time, information about the channel memory parameter μ and the compression parameter m is estimated,
Based on the quantum mismatch information in the steady state, estimate information about the quantum entanglement factor ε,
Wherein the quantum mismatch information is obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ . The method of claim 7, wherein
The probability map Φ ( ρ ) is

Determined by
Where Li and Ri are left eigenoperator and right eigenoperator, λ i is an eigenvalue,
The quantum channel estimation step,
And based on the eigenvalues, information about a zero-temperature dissipation rate Ω, the average number n of photons, and the compression parameter m is estimated. A quantum transmitting device for performing quantum channel prediction,
The density operator ρ is transmitted to a second device as a receiving device through a quantum channel, and information about the probability map Φ ( ρ ) received by the second device through the quantum channel is received from the second device. A receiving interface portion, wherein the quantum channel is a time-correlated compressed generalized amplitude damping (SGAD) channel; And
And a control unit for estimating characteristics of the SGAD channel based on the received probability map (Φ ( ρ )). The method of claim 12,
The probability map Φ ( ρ ) is

Determined by
Where φ _u ( ρ ) is the probability map in the quantum channel, A _i is the Kraus operator, Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k is time-correlated Kraus operator on the quantum channel
The control unit,
And estimating a channel memory parameter [mu] and a compression parameter m, based on the information on the received probability map [phi] ([ rho ]). The method of claim 13,
The control unit,
Obtain concurrence information for the probability maps for the initial density matrices ρ ₁ and ρ ₂ ,
Based on the conference information at a specific time, the channel memory parameter μ and the compression parameter m are estimated,
And estimating a quantum entanglement factor [epsilon] based on the conference information in a steady-state. The method of claim 13,
The control unit,
Obtain information about quantum discord for initial density matrices ρ ₁ and ρ ₂ ,
Based on the quantum mismatch information at a specific time, the channel memory parameter μ and the compression parameter m are estimated,
A quantum entanglement factor ε is estimated based on quantum mismatch information in the steady state. The method of claim 12,
The probability map Φ ( ρ ) is

Determined by
Where Li and Ri are left eigenoperator and right eigenoperator, λ i is an eigenvalue,
The control unit,
And estimating said eigenvalue to obtain a zero-temperature dissipation rate Ω, an average number of photons n, and a compression parameter m. In a quantum receiver device for performing quantum channel prediction,
An interface unit for receiving a density operator ρ transmitted over a quantum channel from a first device, which is a transmitting device, the quantum channel being a time-correlated compressed generalized amplitude damping (SGAD) channel The density operator ρ is received as a probability map Φ ( ρ ) over the SGAD channel; And
And a control unit for estimating characteristics of the SGAD channel based on the received probability map Φ ( ρ ). The method of claim 17,
The probability map Φ ( ρ ) is

Determined by
Where φ _u ( ρ ) is the probability map in the quantum channel, A _i is the Kraus operator, Φ _c ( ρ ) is the probability map in the time-correlated quantum channel, and B _k is time-correlated Kraus operator on the quantum channel
The control unit,
And estimating information on a channel memory parameter [mu] and a compression parameter m, based on the information on the received probability map [phi] ([ rho ]). The method of claim 18,
The control unit,
Estimate information about the channel memory parameter μ and the compression parameter m based on the conference information at a specific time,
Estimating information on the quantum entanglement factor ε estimated by the first device based on the conference information in a steady-state,
And the conference information is obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ . The method of claim 18,
The control unit,
Based on the quantum mismatch information at a specific time, information about the channel memory parameter μ and the compression parameter m is estimated,
Based on the quantum mismatch information in the steady state, estimate information about the quantum entanglement factor ε,
And the quantum mismatch information is obtained from a probability map for initial density matrices ρ ₁ and ρ ₂ .

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