Qualitative analysis of some PDE models of traffic flow

  • We review our previous results on partial differential equation(PDE) models of traffic flow. These models include the first order PDE models, a nonlocal PDE traffic flow model with Arrhenius look-ahead dynamics, and the second order PDE models, a discrete model which captures the essential features of traffic jams and chaotic behavior. We study the well-posedness of such PDE problems, finite time blow-up, front propagation, pattern formation and asymptotic behavior of solutions including the stability of the traveling fronts. Traveling wave solutions are wave front solutions propagating with a constant speed and propagating against traffic.

    Citation: Tong Li. Qualitative analysis of some PDE models of traffic flow[J]. Networks and Heterogeneous Media, 2013, 8(3): 773-781. doi: 10.3934/nhm.2013.8.773

    Related Papers:

    [1] Zhiguo Qu, Shengyao Wu, Le Sun, Mingming Wang, Xiaojun Wang . Effects of quantum noises on χ state-based quantum steganography protocol. Mathematical Biosciences and Engineering, 2019, 16(5): 4999-5021. doi: 10.3934/mbe.2019252
    [2] Dingwei Tan, Yuliang Lu, Xuehu Yan, Lintao Liu, Longlong Li . High capacity reversible data hiding in MP3 based on Huffman table transformation. Mathematical Biosciences and Engineering, 2019, 16(4): 3183-3194. doi: 10.3934/mbe.2019158
    [3] Guodong Ye, Huishan Wu, Kaixin Jiao, Duan Mei . Asymmetric image encryption scheme based on the Quantum logistic map and cyclic modulo diffusion. Mathematical Biosciences and Engineering, 2021, 18(5): 5427-5448. doi: 10.3934/mbe.2021275
    [4] Yongju Tong, YuLing Liu, Jie Wang, Guojiang Xin . Text steganography on RNN-Generated lyrics. Mathematical Biosciences and Engineering, 2019, 16(5): 5451-5463. doi: 10.3934/mbe.2019271
    [5] Yanfeng Shi, Shuo Qiu, Jiqiang Liu, Tinghuai Ma . Novel efficient lattice-based IBE schemes with CPK for fog computing. Mathematical Biosciences and Engineering, 2020, 17(6): 8105-8122. doi: 10.3934/mbe.2020411
    [6] Xin Wang, Bo Yang . An improved signature model of multivariate polynomial public key cryptosystem against key recovery attack. Mathematical Biosciences and Engineering, 2019, 16(6): 7734-7750. doi: 10.3934/mbe.2019388
    [7] Liyun Liu, Zichi Wang, Zhenxing Qian, Xinpeng Zhang, Guorui Feng . Steganography in beautified images. Mathematical Biosciences and Engineering, 2019, 16(4): 2322-2333. doi: 10.3934/mbe.2019116
    [8] Xianyi Chen, Anqi Qiu, Xingming Sun, Shuai Wang, Guo Wei . A high-capacity coverless image steganography method based on double-level index and block matching. Mathematical Biosciences and Engineering, 2019, 16(5): 4708-4722. doi: 10.3934/mbe.2019236
    [9] P. Balamanikandan, S. Jeya Bharathi . A mathematical modelling to detect sickle cell anemia using Quantum graph theory and Aquila optimization classifier. Mathematical Biosciences and Engineering, 2022, 19(10): 10060-10077. doi: 10.3934/mbe.2022470
    [10] Melanie A. Jensen, Qingzhou Feng, William O. Hancock, Scott A. McKinley . A change point analysis protocol for comparing intracellular transport by different molecular motor combinations. Mathematical Biosciences and Engineering, 2021, 18(6): 8962-8996. doi: 10.3934/mbe.2021442
  • We review our previous results on partial differential equation(PDE) models of traffic flow. These models include the first order PDE models, a nonlocal PDE traffic flow model with Arrhenius look-ahead dynamics, and the second order PDE models, a discrete model which captures the essential features of traffic jams and chaotic behavior. We study the well-posedness of such PDE problems, finite time blow-up, front propagation, pattern formation and asymptotic behavior of solutions including the stability of the traveling fronts. Traveling wave solutions are wave front solutions propagating with a constant speed and propagating against traffic.


    Compared with classical information hiding, quantum information hiding has unparalleled advantages based on the non-cloning theorem, uncertainty principle, quantum non-locality, such as good security and high information transmission efficiency. Since Bennett and Brassard proposed the first quantum cryptography communication protocol in 1984 [1], many quantum cryptographic communication protocols such as quantum key distribution (QKD) [2,3,4], quantum identity authentication (QIA) [5], quantum secrets sharing (QSS) [6,7,8] and quantum security direct communications (QSDC) [9,10] have emerged. In recent years, the theoretical research and application of quantum communication has been developed in a variety of ways, including quantum computation [11], quantum remote state preparation [12,13,14], quantum network coding [15,16], quantum auction [17] and quantum machine learning [18,19].

    Among them, quantum steganography, as a research branch of quantum information hiding, aims at covertly transmitting secret information in public quantum channel. Usually, it can be mainly divided into two categories. The first one is to use quantum communication characteristics to perform covert communication through single-particle or multi-particle as quantum carriers [20,21,22]. In 2018, Zhu et al. proposed a novel quantum steganography protocol based on Brown entangled states, which proved its good security resisting on quantum noise [23]. The second is to embed secret information into various multimedia carriers for covert communication [24,25]. In 2018, Qu et al. proposed a novel quantum image steganography algorithm based on exploiting modification direction [26].

    So far, most of the previous quantum steganography protocols are mainly based on discrete variables. Recently, the continuous variable quantum communication technique is beginning to emerge [27]. It uses a classical light source as a signal source, and can encode information on a continuously changing observable physical quantity with low cost due to easy implementation. The encoded information is a symbol, which can be restored to binary bits only after some specific data processing. Therefore, the capacity of this technique can be large and the key generation rate is also high, which has quickly attracted widespread attention. As an example, the continuous-variable quantum key distribution (CVQKD) has absolute advantages over the discrete-variable quantum key distribution (DVQKD). The detection of DVQKD is based on single photons. The single photon signal is not only difficult to manufacture, but also difficult to be detected and costly. The CVQKD is using homodyne/heterodyne decoding to obtain quadrature encoding, which greatly improves the technical efficiency. In addition, non-Gaussian operations have many applications in improving the quantum entanglement and teleportation. In 2003, Olivares et al. proposed the Inconclusive photon subtraction (IPS) to improve teleportation [28]. In 2015, Wu et al. applied local coherent superposition of photon subtraction and addition to each mode of even entangled coherent state to introduce a new entangled quantum state [29]. In 2018, the CVQKD with non-Gaussian quantum catalysis was proposed [30].

    In this paper, a continuous variable quantum steganography protocol is proposed based on the continuous variable GHZ entangled state [31] and the continuous variable quamtum identity authentication protocol [32]. The protocol can realize the transmission of deterministic secret information in public quantum channel of identity authentication. It can convert segmented secret information into the whole secret information by adopting the specific encoding rule, randomly selecting quantum channel and replacing time slot. Through effectively verifying the identity of users, in the new protocol, the secret information can be implicitly transmitted to the recipient Bob, while the eavesdropper Eve disables to detect the existence of covert communication. Compared with the previous quantum steganography protocols, by introducing continuous variables into quantum steganography and making full use its characteristics of continuous variable, the proposed protocol can obtain the advantages of good imperceptibility, security and easy implementation for good applicability.

    The paper is organized as follows. Section 2 introduces some basic knowledge about optics, the preparation of continuous variable GHZ states, and the principle of continuous variable quantum telecommuting required for the identity authentication process. Section 3 describes the concrete steps of the new continuous variable quantum steganography protocol in detail. Section 4 mainly analyzes the new protocol's imperceptibility, security and efficiency of information transmission, even in quantum noise environment. The conclusions are given in Section 5.

    We first review some of the knowledge of quantum optics. By using the creation operator $ {a^\dagger }$ and the annihilation operator $ a $, the two regular components including the amplitude x and the phase p of a beam can be expressed as

    $ x=12(a+a)
    $
    (2.1)
    $ p=i2(aa)
    $
    (2.2)

    where $ {a^\dagger } $ and $ a $ satisfy boson reciprocity $ \left[{a, a} \right] = \left[{{a^\dagger }, {a^\dagger }} \right]{\rm{ = 0}} $, $ \left[{a, {a^\dagger }} \right] = 1 $. Therefore $ \left[{x, p} \right] = \frac{i}{2} $, two typical components x and p satisfy the Heisenberg uncertainty principle: $ \Delta x \cdot \Delta p \ge \frac{1}{4} $.

    A squeezed beam can be defined as

    $ |α,r=x+ip=erx(0)+ierp(0)
    $
    (2.3)

    where $ r $ is the compression factor. If $ r < 0 $, it indicates that the beam amplitude is compressed; if $ r > 0 $, it indicates that the beam phase is compressed. $ x\left(0 \right) $ and $ p\left(0 \right) $ indicate the amplitude and the phase of the vacuum state respectively, and $ \; x\left(0 \right), p\left(0 \right) \sim N\left({0, \frac{1}{4}} \right) $.

    In the proposed protocol, the legal communication parties share the encoding rule in advance. They can encode the discrete information into different intervals(Turbo codes [33] or LDPC code [34]).

    The continuous variable GHZ state is very important for quantum information processing and quantum communication in the new protocol. As shown in Figure 1, the continuous variable GHZ state is produced by making two squeezed vacuum states $ {a_{in1}} $ and $ {a_{in2}} $ pass through a beam splitter $ B{S_1} $ (transmission coefficient is 0.5) to generate $ {a_{out1}} $ and $ a_{in3}^ * $ firstly. And then, it makes $ a_{in3}^ * $ and another squeezed vacuum state $ {a_{in3}} $ pass through a beam splitter $ B{S_2} $ (transmission coefficient is 1) to generate $ {a_{out2}} $ and $ {a_{out3}} $. Obviously, $ {a_{out1}} $, $ {a_{out2}} $ and $ {a_{out3}} $ is a set of the continuous variable GHZ entangled state that be defined as

    $ xout1=13er1xin1(0)+23er2xin2(0)
    $
    (2.4)
    $ pout1=13er1pin1(0)+23er2pin2(0)
    $
    (2.5)
    $ xout2=13er1xin1(0)16er2xin2(0)+12er3xin3(0)
    $
    (2.6)
    $ pout2=13er1pin1(0)16er2pin2(0)+12er3pin3(0)
    $
    (2.7)
    $ xout3=13er1xin1(0)16er2xin2(0)12er3xin3(0)
    $
    (2.8)
    $ pout3=13er1pin1(0)16er2pin2(0)12er3pin3(0)
    $
    (2.9)
    Figure 1.  Preparation of continuous variable GHZ state.

    Let suppose that $ {r_1} = {r_2} = {r_3} = r $, it can calculate the correlation of amplitude and phase between $ {a_{out1}} $, $ {a_{out2}} $ and $ {a_{out3}} $

    $ [Δ(xout1xout2)]2=(1234)e2r
    $
    (2.10)
    $ [Δ(xout1xout3)]2=(12+34)e2r
    $
    (2.11)
    $ [Δ(pout1+pout2+pout3)]2=34e2r
    $
    (2.12)

    If the compression parameter $ r \to + \infty $, the correlation between the output optical modes $ {a_{out1}} $, $ {a_{out2}} $ and $ {a_{out3}} $ will become stronger and stronger

    $ limr+(xout1xout2)=limr+(xout1xout3)=0
    $
    (2.13)
    $ limr+(pout1+pout2+pout3)=0
    $
    (2.14)

    It is obvious that the amplitude between any two of the continuous variable GHZ state output modes is positively correlated, and the phase between them also has the entanglement characteristic.

    The principle of continuous variable quantum telecommuting can be described as shown in Figure 2. Alice prepares a coherent state $ {a_A} = \left| {{x_A} + i{p_A}} \right\rangle $ to be transmitted. Simultaneously, Alice and Bob share two entangled optical modes $ {a_{out1}} $ and $ {a_{out2}} $. After everything is ready, Alice sends the coherent state and $ {a_{out1}} $ through a 50/50 beam splitter for Bell state measurement to obtain $ {x_o} $ and $ {p_o} $

    $ xo=12(xAxout1)
    $
    (2.15)
    $ po=12(pA+pout1)
    $
    (2.16)
    Figure 2.  The principle of continuous variable quantum telecommuting.

    After Alice announces the measurement results through the classic channel, Bob takes the corresponding unitary operation $ D\left({\beta {\rm{ = }}\sqrt {\rm{2}} \left({{x_o} + i{p_o}} \right)} \right) $ on $ {a_{out2}} $ to obtain

    $ xB=xout2+2xo=xA(xout1xout2)
    $
    (2.17)
    $ pB=pout2+2po=pA+(pout1+pout2)
    $
    (2.18)

    According to Eqs. (2.13) and (2.14), if the compressing parameter $ r \to + \infty $, we can obtain $ {x_B} = {x_A} $, $ {p_B} = {p_A} - {p_{out3}} $. It means that Alice and Bob obtain a highly correlated sequence on the amplitude component. Therefore, in the proposed protocol, we only modulate the effective information on the amplitude component and the uncorrelated random information $ n $ on the phase component.

    We propose a novel continuous variable quantum steganography protocol based on quantum identity authentication protocol and continuous variable GHZ state. It can effectively transmit deterministic secret information in the public quantum channel. When Bob attempts to communicate with Alice, they need to share an initial identity key $ {K_1} $ and a series of time slot keys $ \; T $ which are binary sequences known only to Alice and Bob in advance. Here, $ D\left(\alpha \right) $, $ D\left({{\alpha _1}} \right) $ and $ D\left({{\alpha _1}^\prime } \right) $ are the displacement operation; $ D\left(o \right) $ is the unitary operation, and $ H $ is the fidelity parameter. The yellow area represents the normal information transmission mode. The red area represents the secret information transmission mode.

    The details of the protocol are shown in Figure 3. We assume that the quantum channel is lossless, the proposed protocol is as follows.

    Figure 3.  Continuous variable quantum steganography protocol.

    Alice prepares the continuous variable GHZ entangled states $ {a_{out1}} $, $ {a_{out2}} $ and $ {a_{out3}} $. Alice keeps $ {a_{out1}} $ by herself, then transmits $ {a_{out2}} $ and $ {a_{out3}} $ to Bob through two quantum channels R1 and R2 respectively. Alice randomly selects a quantum channel for normal information transmission mode (identity authentication). The other is the channel of the secret information transmission mode (steganographic information).

    The normal information transmission mode:

    (A1) Alice chooses $ {a_{out2}} $ (R1 channel) or $ {a_{out3}} $ (R2 channel) to send to Bob. For convenience, we assume that the channel selected by the normal information transmission mode is the R1 channel.

    (A2) After Alice confirms that Bob has received $ {a_{out2}} $, she converts $ {K_1} $ to decimal sequence $ {k_1} $. And then, Alice selects two decimal numbers $ {k_2} $ and $ v $, satisfying the normal distribution $ N\left({0, {\sigma ^2}} \right) $. Alice prepares a vacuum state $ \left| 0 \right\rangle $ with displacement operation $ D\left({{\alpha _1}{\rm{ = }}\left({{k_1} + {k_2}} \right) + in} \right) $. The coherent state optical mode $ {a_1} $ which is used to update the identity key, is obtained. Simultaneously, Alice also prepares a vacuum state with displacement operation $ D\left({{\alpha _1}^\prime = ({k_1} + v) + in} \right) $. The coherent state optical mode $ {a_1}^\prime $, which is used as a decoy state for identity authentication, is obtained. After that, Alice randomly selects $ {a_1} $ or $ {a_1}^\prime $ to make Bell state measurement with $ {a_{out1}} $ on each time slot and obtains, $ {x_o} = \frac{1}{{\sqrt 2 }}\left({{x_1} - {x_{out1}}} \right) $ and $ {p_o} = \frac{1}{{\sqrt 2 }}\left({{p_1} + {p_{out1}}} \right) $, or $ {x_o} = \frac{1}{{\sqrt 2 }}\left({{x_1}^\prime - {x_{out1}}} \right) $ and $ {p_o} = \frac{1}{{\sqrt 2 }}\left({{p_1}^\prime + {p_{out1}}} \right) $. Then, Alice announces $ {x_o} $ and $ {p_o} $ to Bob through the public classic channel.

    (A3) According to the received $ {x_o} $ and $ {p_o} $, Bob performs the unitary operation $ D\left({o = \sqrt 2 \left({{x_o} + i{p_o}} \right)} \right) $ on the received $ {a_{out2}} $, and then selects the amplitude component to measure and get the sequence $ \delta $. Alice publishes the time slots $ t $ which used $ {a_1}^\prime $, and Bob measures the amplitude components on these time slots to obtain a sequence $ {\delta _1}^\prime $. The value of sequence $ \delta $ minus sequence $ {\delta _1}^\prime $ is defined as $ {\delta _1} $.

    (A4) Bob converts $ {K_1} $ to a decimal sequence $ {k_1}^\prime $, then calculates $ v' = {\delta _{\rm{1}}}^\prime - {k_1}^\prime $. After Bob announces $ v' $, Alice calculates a fidelity parameter $ H = {\left\langle {{{\left[{v'- \varphi v} \right]}^2}} \right\rangle _{\min }} $. In the lossless channel, we get $ \varphi {\rm{ = }}1 $. If the calculation $ H $ is equal to 0, it means $ {k_1} = {k_1}^\prime $. The user identity is verified to be legal. Bob then updates the identity key sequence $ {\delta _1} - {k_1}^\prime $ to obtain $ {k_2} $. If $ H $ is greater than 0, it means that the eavesdropper Eve exists or the user is illegal. As a result, the communication will be abandoned.

    The secret information transmission mode:

    (B1) Alice divides her steganographic information into p-blocks for block transmission. Let assume that the steganographic information of the q-th block $ \left({q \le p} \right) $ is 010. According to the previously shared encoding rule, steganographic information 010 corresponds to the interval $ \left({ - 2, - 1} \right] $. After that, Alice takes the first time slot $ {T_a} $ from the binary time slot key $ T $ and converts it to a decimal number $ {t_a} $. And then, she chooses the random variable $ m \in \left({ - 2, - 1} \right] $, and does the translation operation $ D\left({\alpha = \; m + in} \right) $ on $ {a_{out3}} $ in the time slot $ {t_a} $ to get $ {a_{out3}}^\prime $, where $ m $ is the secret information that needs to be transmitted. Alice sends $ {a_{out3}}^\prime $ to Bob via quantum channel R2.

    (B2) Bob also obtains $ {t_a} $ based on the shared time slot key, and measures the amplitude component of the received beam mode $ {a_{out3}}^\prime $ in the time slot $ {t_a} $ to obtain the sequence $ {\xi _1} $. After that, Bob then selects the time slot $ {t_u}\left({u \ne a} \right) $ to measure the amplitude component for obtaining the sequence $ {\xi _2} $. Bob calculates $ {\xi _1}{\rm{ - }}{\xi _2} $ to obtain the secret information $ m $.

    (B3) According to the previously shared encoding rule, the information of the q-th block is obtained by Bob. The identity keys of both parties are also updated, and the transmission of the secret information of this block is completed. In the next round, Alice randomly selects one quantum channel for normal information transmission mode, and another quantum channel for secret information transmission mode. Then Alice repeats the above steps until all the steganographic information are transmitted.

    As shown in Figure 3, when Alice wants to transmit private information to Bob, she randomly selects a quantum channel for identity authentication by using the modulated vacuum states and the continuous variable quantum telecommuting. At the same time, after the encoded secret information is modulated in the shared time slot, the transmission of the secret information is also carried out in another quantum channel. Under the cover of determining whether the Bob's identity is legal, it is difficult for an eavesdropper to discover that another channel is transmitting information. Even if the eavesdropper knows the existence of the secret information, it is impossible to obtain useful information without knowing the modulated time slot and the encoding rule.

    In the field of experiment, the protocol is also feasible. The secure transmission using entangled squeezed states has been exemplified [35]. The experimental demonstration of the continuous variable quantum telecommuting has also been proposed [36]. Our protocol is mainly based on these two techniques. Therefore, this protocol is capable of having good performance in experiments.

    The security of the scheme is mainly based on the entanglement properties of the GHZ state, the specific encoding rule, the shared time slot key and the block transmission. Among them, quantum entanglement guarantees the correlation of quantum transmission. The encoding rule ensures that the information in the quantum channel is not completely equal to the identity key information. The shared time slot key decides the writing and reading of the secret information.

    The normal message transmission mode is to avoid Eve's active attack through identity authentication. In order to conduct an active attack, Eve needs to be authenticated. The most effective method is to obtain an updated authentication key and implement an active attack in the next authentication flow. In order to obtain the updated authentication key, Eve's good optional method is to intercept all the quantum signals sent by Alice and measure their components. Combined with the information sent by the classic channel, Eve can recover the updated authentication key and prepare a quantum state to send to Bob during an authentication process. However, due to the quantum uncertainty principle, Eve will inevitably introduce excessive noise, which will be detected by the legal user through the calculation of the fidelity parameter. As shown in Figure 3, there are two quantum channels and two classical channels in the proposed protocol. We have always assumed that the information transmitted in the classical channel is public, and the security of the normal information transmission mode has been proved above [32]. Therefore, we focus on the security of the secret information transmission mode.

    It's noteworthy that this protocol may suffer from physical attacks, such as the wavelength attack. This kind of attack makes full of use of the potential imperfections in the protocol's implementation to enable the eavesdropper to control the light intensity transmission of the receiver's splitter. The attack method is to intercept the beam and measure the signal using the local oscillator by heterodyne measurement to obtain the quadrature values, and then switch the wavelength of the input light. It can make the eavesdropper completely control the receiver's beam splitter without being discovered. In this case, the new protocol is also capable of resisting the attack by randomly adding or not adding a wavelength filter before the monitoring detector and observing the difference value [37].

    Because only two quantum channels (R1 and R2) are used to transmit quantum information and the information is modulated on the amplitude and phase of the beam, the attacker Eve can take an attack by using a spectroscope to intercept the signal for measurement and attempting to obtain the key. As shown in Figure 4, Let assume that the spectroscopic coefficient used by Eve is $ \gamma \left({0 \le \gamma \le 1} \right) $. The two beams $ {a_{A1}} $ and $ {a_{A2}} $ sent by Alice pass through the beam splitter and become

    $ aB1=γaA1+1γaN1
    $
    (4.1)
    $ aB2=γaA2+1γaN2
    $
    (4.2)
    Figure 4.  The spectroscopic noise attack.

    Eve can obtain $ {a_{E1}} $ and $ {a_{E2}} $

    $ aE1=γaN11γaA1
    $
    (4.3)
    $ aE2=γaN21γaA2
    $
    (4.4)

    According to the difference of the spectroscopic coefficients, the safety analysis can be carried out in three cases:

    1. If $ \gamma = 0 $, Eve intercepts all signals. In this case, Eve may combine $ {a_{E1}} $ and $ {a_{E2}} $ with the Bell state measurement to obtain

    $ xu=12(xE1xE2)=12(xA1xA2)
    $
    (4.5)
    $ pu=12(pE1+pE2)=12(pA1+pA2)
    $
    (4.6)

    Due to the correlation between the amplitudes of $ {a_{A1}} $ and $ {a_{A2}} $, Eve measures the amplitude component, as $ {x_u} \to 0 $. Even if the time slot containing the secret information has been stolen, Eve disables to get any information. The phase of $ {a_{A1}} $ and $ {a_{A2}} $ does not modulate the secret information, and only the uncorrelated random information $ n $ exists. Therefore, Eve will only think that it is the ordinary noise in the quantum channel, so that the transmission of the secret information can be undetected.

    Eve may also measure $ {a_{A1}} $ and $ {a_{A2}} $ separately. According to the principle of key modulation, let assume that Eve measures the amplitude of $ {a_{A1}} $ and the phase of $ {a_{A2}} $ respectively. Because the correlation of amplitude, Eve can recover $ {a_{A2}} $ after measurement. However, due to the quantum uncertainty principle, Eve cannot recover the phase of $ {a_{A1}} $ and this operation will reduce the phase entanglement of the GHZ state. It will inevitably be detected by performing eavesdropping detection from legitimate parties.

    It can be seen that Eve's eavesdropping will be detected by legitimate parties, and this protocol can safely transmit secret information when $ \gamma = 0 $.

    2. If $ \gamma {\rm{ = 1}} $, Eve does not take any action, obviously cannot get any information.

    3. When $ 0 \le \gamma \le 1 $, Eve only intercepts part of the signal, and another part of the signal is still transmitted to the receiver.

    In this case, due to the entanglement properties of the GHZ state, Eve cannot obtain effective information with the Bell state measurement, so Eve can only operate on $ {a_{E1}} $ and $ {a_{E2}} $ separately. Because the secret information is modulated on one of the quantum channels, let choose $ {a_{E1}} $ to analyze it as an example. Let Assume that the quantum channel transmission efficiency is $ \lambda $, the signal received by Bob will be

    $ aB1=λaA1+1λaN1
    $
    (4.7)

    Eve needs to amplify $ {a_{E1}} $ to avoid being detected and sends it to Bob with $ {a_{B1}} $. The effective signal received by Bob is

    $ a=gaE1+aB1
    $
    (4.8)

    Here, $ g $ is the gain compensation. According to Eqs. (4.1), (4.3) and (4.8), in order to receive the signal $ \sqrt \lambda {a_{A1}} $ for Bob, it needs to be satisfied with

    $ λaA1=g1γaA1+γaA1
    $
    (4.9)

    Eve obtain $ g = \frac{{\sqrt \gamma - \sqrt \lambda }}{{\sqrt {1 - \gamma } }} $. Due to the information is modulated on the amplitude component, the noise signal received by Bob will be

    $ aN=1λγ1γxN1
    $
    (4.10)

    If $ \gamma \ne \lambda $ and $ {a_N} \ne \sqrt {1 - \lambda } {x_{N1}} $, the signal-to-noise ratio received by Bob will change. The legitimate parties will find Eve in the eavesdropping detection. If $ \gamma {\rm{ = }}\lambda $, $ g{\rm{ = }}0 $, it does not require the gain compensation. Eve will be undetected by the legitimate parties.

    Therefore, if $ 0 \le \gamma \le 1 $, Eve can adopt the best attack method is intercepting by a beam splitter with the same spectroscopic coefficient and channel transmission efficiency. The signal received by Eve will be

    $ aE1=λaN11λaA1
    $
    (4.11)

    The signal received by Bob is

    $ aB1=λaA1+1λaN1
    $
    (4.12)

    According to Eq. (2.6), the amplitude components of Eve and Bob are obtained as follows

    $ xE1=λxN11λ[13erxin1(0)16erxin2(0)+12erxin3(0)]
    $
    (4.13)
    $ xB1=λ[13erxin1(0)16erxin2(0)+12erxin3(0)]+1λxN1
    $
    (4.14)

    Here, $ {x_{N1}} \sim N\left({0, {V_{N1}}} \right) $. If we measure the amplitude of $ {a_{B1}} $, only $ \sqrt {\frac{\lambda }{3}} {e^r}{x_1}\left(0 \right) $ will be the effective signal, while the rest are noise. The signal-to-noise ratio of Bob can be calculated as

    $ MB1NB1=λe2r2λe2r+12(1λ)VN1
    $
    (4.15)

    The amount of information between Alice and Bob is

    $ I(A,B)=12log2(1+MB1NB1)
    $
    (4.16)

    Similarly, the signal-to-noise ratio of Eve is

    $ ME1NE1=(1λ)e2r2(1λ)e2r+12λVN1
    $
    (4.17)

    The amount of information between Alice and Eve is

    $ I(A,E)=12log2(1+ME1NE1)
    $
    (4.18)

    Therefore, according to the Shannon information theory, the quantum channel transmission rate is

    $ ΔI=I(A,B)I(A,E)=12log2(λ(e2r+2e2r)+12(1λ)VN12λe2r+12(1λ)VN12(1λ)e2r+12λ(1λ)(e2r+2e2r)+12λVN1)
    $
    (4.19)

    If $ {V_{N1}}{\rm{ = }}\frac{1}{4} $, the secret information transmission rate obtained by Eq. (4.19) is as shown in Figure 5. The secret information transmission rate $ \Delta I $ is proportional to the quantum channel transmission efficiency $ \lambda $. If the channel transmission efficiency $ \lambda < 0.5 $, the information transmission rate $ \Delta I < 0 $, the amount of information acquired by Eve is greater than the amount of information obtained by Bob, so that the channel is unsafe. If the channel transmission efficiency $ \lambda > 0.5 $, the information transmission rate $ \Delta I > 0 $, the secret information transmission can be carried out safely. The security of the proposed protocol is also dependent on the entanglement properties of the continuous variable GHZ state. If the compression parameter $ r = 0 $, the information transmission rate will reach 0. It is almost impossible to transmit information. If the compression parameter $ r $ increases, the information transmission rate also increases. Compared with discrete variable communication, it can also greatly reduce the quantum states that need to be prepared and shorten the time required for information transmission. For example, the discrete variables communication can only transmit 1 bit of classical information per qubit. If a deterministic key of 1000 bits is needed, at least 1000 qubits are required. In the proposed protocol, if $ r = 3 $ and the channel transmission efficiency is equal to 0.9, the information transmission rate will be 4 qubits/s. At this point, only 250 qubits is required to complete the same work. So it's obviously that the efficiency of information transmission can be greatly improved.

    Figure 5.  Secret information transmission rate ($ {V_{N1}}{\rm{ = }}\frac{1}{4} $).

    This paper proposes a novel continuous variable quantum steganography protocol based on quantum identity authentication. For covert communication, the protocol implements the transmission of secret information in public channel of quantum identity authentication. Compared with the existing quantum steganography results, by taking full advantage of entanglement properties of continuous variable GHZ state, this protocol not only has the advantages of good imperceptibility and easy implementation in physics, but also good security and information transmission efficiency, even under eavesdropping attacks especially to the spectroscopic noise attack. In addition, the capacity of secret information is potential to be enlarged by introducing better information coding method.

    This work was supported by the National Natural Science Foundation of China (No. 61373131, 61601358, 61501247, 61672290, 61303039, 61232016), the Six Talent Peaks Project of Jiangsu Province (Grant No. 2015-XXRJ-013), Natural Science Foundation of Jiangsu Province (Grant No. BK20171458), the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (China under Grant No.16KJB520030), Sichuan Youth Science and Technique Foundation (No.2017JQ0048), NUIST Research Foundation for Talented Scholars (2015r014), PAPD and CICAEET funds.

    The authors declare no conflict of interest.

    [1] A. Aw and M. Rascle, Resurrection of "second order" models of traffic flow, SIAM J. Appl. Math., 60 (2000), 916-938. doi: 10.1137/S0036139997332099
    [2] M. Bando, K. Hasebe, A. Nakayama, A. Shibata and Y. Sugiyama, Dynamical model of traffic congestion and numerical simulation, Phys. Rev. E, 51 (1995), 1035-1042.
    [3] N. Bellomo and C. Dogbe, On the modeling of traffic and crowds: A survey of models, speculations, and perspectives, SIAM Rev., 53 (2011), 409-463. doi: 10.1137/090746677
    [4] N. Bellomo and V. Coscia, First order models and closure of the mass conservation equation in the mathematical theory of vehicular traffic flow, C. R. Mecanique, 333 (2005), 843-851. doi: 10.1016/j.crme.2005.09.004
    [5] F. Berthelin, P. Degond, M. Delitala and M. Rascle, A model for the formation and evolution of traffic jams, Arch. Rational Mech. Anal., 187 (2008), 185-220. doi: 10.1007/s00205-007-0061-9
    [6] F. Berthelin, P. Degond, V. Le Blanc, S. Moutari, M. Rascle and J. Royer, A traffic-flow model with constraints for the modelling of traffic jams, Math. Mod. Meth. Appl. Sci., 18 (2008), (Supplement), 1269-1298. doi: 10.1142/S0218202508003030
    [7] V. Coscia, On a closure of mass conservation equation and stability analysis in the mathematical theory of vehicular traffic flow, C. R. Mecanique, 332 (2004), 585-590. doi: 10.1016/j.crme.2004.03.016
    [8] C. Daganzo, Requiem for second-order approximations of traffic flow, Transportation Research, B, 29 (1995), 277-286. doi: 10.1016/0191-2615(95)00007-Z
    [9] P. Degond and M. Delitala, Modelling and simulation of vehicular traffic jam formation, Kinetic Related Models, 1 (2008), 279-293. doi: 10.3934/krm.2008.1.279
    [10] D. Helbing, Improved fluid-dynamic model for vehicular traffic, Physical Review E, 51 (1995), 3154-3169. doi: 10.1103/PhysRevE.51.3164
    [11] D. Helbing, Traffic and related self-driven many-particle systems, Rev. Modern Phy., 73 (2001), 1067-1141. doi: 10.1103/RevModPhys.73.1067
    [12] D. Helbing, Derivation of non-local macroscopic traffic equations and consistent traffic pressures from microscopic car-following models, Eur. Phys. J. B, 69 (2009), 539-548.
    [13] S. Jin and Jian-Guo Liu, Relaxation and diffusion enhanced dispersive waves, Proceedings: Mathematical and Physical Sciences, 446 (1994), 555-563.
    [14] W. L. Jin and H. M. Zhang, The formation and structure of vehicle clusters in the Payne-Whitham traffic flow model, Transportation Research, B., 37 (2003), 207-223. doi: 10.1016/S0191-2615(02)00008-5
    [15] B.S. Kerner and P. Konhäuser, Structure and parameters of clusters in traffic flow, Physical Review E, 50 (1994), 54-83. doi: 10.1103/PhysRevE.50.54
    [16] A. Klar and R. Wegener, Kinetic derivation of macroscopic anticipation models for vehicular traffic, SIAM J. Appl. Math., 60 (2000), 1749-1766. doi: 10.1137/S0036139999356181
    [17] R. D. Kühne, Macroscopic freeway model for dense traffic-stop-start waves and incident detection, Ninth International Symposium on Transportation and Traffic Theory, VNU Science Press, Ultrecht, 1984, 21-42.
    [18] A. Kurganov and A. Polizzi, Non-oscillatory central schemes for traffic flow models with Arrhenius look-ahead dynamics, Netw. Heterog. Media, 4 (2009), 431-451. doi: 10.3934/nhm.2009.4.431
    [19] D. A. Kurtze and D. C. Hong, Traffic jams, granular flow, and soliton selection, Phys. Rev. E, 52 (1995), 218-221. doi: 10.1103/PhysRevE.52.218
    [20] H. Y. Lee, H.-W. Lee and D. Kim, Steady-state solutions of hydrodynamic traffic models, Phys. Rev. E, 69 (2004), 016118. doi: 10.1103/PhysRevE.69.016118
    [21] Dong Li and Tong Li, Shock formation in a traffic flow model with arrhenius look-ahead dynamics, Networks and Heterogeneous Media, 6 (2011), 681-694. doi: 10.3934/nhm.2011.6.681
    [22] Tong Li, Global solutions and zero relaxation limit for a traffic flow model, SIAM J. Appl. Math., 61 (2000), 1042-1061. doi: 10.1137/S0036139999356788
    [23] Electron. J. Diff. Eqns., 2001 18 pp. (electronic).
    [24] Tong Li, Well-posedness theory of an inhomogeneous traffic flow model, Discrete and Continuous Dynamical Systems, Series B, 2 (2002), 401-414. doi: 10.3934/dcdsb.2002.2.401
    [25] Tong Li, Global solutions of nonconcave hyperbolic conservation laws with relaxation arising from traffic flow, J. Diff. Eqns., 190 (2003), 131-149. doi: 10.1016/S0022-0396(03)00014-7
    [26] Tong Li, Mathematical modelling of traffic flows, Hyperbolic problems: Theory, numerics, applications, 695-704, Springer, Berlin, 2003.
    [27] Tong Li, Modelling traffic flow with a time-dependent fundamental diagram, Math. Methods Appl. Sci., 27 (2004), 583-601. doi: 10.1002/mma.470
    [28] Tong Li, Nonlinear dynamics of traffic jams, Physica D, 207 (2005), 41-51. doi: 10.1016/j.physd.2005.05.011
    [29] Tong Li, Instability and formation of clustering solutions of traffic flow, Bulletin of the Institute of Mathematics, Academia Sinica (New Series), 2 (2007), 281-295.
    [30] Tong Li, Stability of traveling waves in quasi-linear hyperbolic systems with relaxation and diffusion, SIAM J. Math. Anal., 40 (2008), 1058-1075. doi: 10.1137/070690638
    [31] Tong Li and Hailiang Liu, Stability of a traffic flow model with nonconvex relaxation, Comm. Math. Sci., 3 (2005), 101-118.
    [32] Tong Li and Hailiang Liu, Critical thresholds in hyperbolic relaxation systems, J. Diff. Eqns., 247 (2009), 33-48. doi: 10.1016/j.jde.2009.03.032
    [33] Tong Li and Hailiang Liu, Critical thresholds in a relaxation system with resonance of characteristic speeds, Discrete and Continuous Dynamical Systems - Series A, 24 (2009), 511-521. doi: 10.3934/dcds.2009.24.511
    [34] Tong Li and Hailiang Liu, Critical thresholds in a relaxation model for traffic flows, Indiana Univ. Math. J., 57 (2008), 1409-1430. doi: 10.1512/iumj.2008.57.3215
    [35] Tong Li and Yaping Wu, Linear and nonlinear exponential stability of traveling waves for hyperbolic systems with relaxation, Comm. Math. Sci., 7 (2009), 571-593.
    [36] Tong Li and H. M. Zhang, The mathematical theory of an enhanced nonequilibrium traffic flow model, Network and Spatial Economics, A Journal of Infrastructure Modeling and Computation, Special Double Issue on Traffic Flow Theory, 1&2 (2001), 167-177.
    [37] M. J. Lighthill and G. B. Whitham, On kinematic waves: II. A theory of traffic flow on long crowded roads, Proc. Roy. Soc., London, Ser., A229 (1955), 317-345. doi: 10.1098/rspa.1955.0089
    [38] T. Nagatani, The physics of traffic jams, Rep. Prog. Phys., 65 (2002), 1331-1386. doi: 10.1088/0034-4885/65/9/203
    [39] K. Nagel, Particle hopping models and traffic flow theory, Phys. Rev. E, 53 (1996), 4655-4672.
    [40] O. A. Oleinik, Discontinuous solutions of non-linear differential equations, (Russian) Uspehi. Mat. Nauk., 12 (1957), 3-73.
    [41] H. J. Payne, Models of freeway traffic and control, "Simulation Councils Proc. Ser. : Mathematical Models of Public Systems," 1 (1971), 51-61, Editor G.A. Bekey, La Jolla, CA.
    [42] I. Prigogine and R. Herman, "Kinetic Theory of Vehicular Traffic," American Elsevier Publishing Company Inc., New York, 1971.
    [43] P. I. Richards, Shock waves on highway, Operations Research, 4 (1956), 42-51. doi: 10.1287/opre.4.1.42
    [44] A. Sopasakis and M. Katsoulakis, Stochastic modeling and simulation of traffic flow: Asymmetric single exclusion process with Arrhenius look-ahead dynamics, SIAM J. Appl. Math., 66 (2006), 921-944. doi: 10.1137/040617790
    [45] Lina Wang, Yaping Wu and Tong Li, Exponential stability of large-amplitude traveling fronts for quasi-linear relaxation systems with diffusion, Physica D, 240 (2011), 971-983. doi: 10.1016/j.physd.2011.02.003
    [46] G. B. Whitham, "Linear and Nonlinear Waves," Pure and Applied Mathematics. Wiley-Interscience [John Wiley & Sons], New York-London-Sydney, 1974. xvi+636 pp.
    [47] Lei Yu, Tong Li and Zhong-Ke Shi, Density waves in a traffic flow model with reactive-time delay, Physica A, Statistical Mechanics and its Applications, 389 (2010), 2607-2616. doi: 10.1016/j.physa.2010.03.009
    [48] Lei Yu, Tong Li and Zhong-Ke Shi, The effect of diffusion in a new viscous continuum model, Physics Letters, Section A: General, Atomic and Solid State Physics, 374 (2010), 2346-2355. doi: 10.1016/j.physleta.2010.03.056
    [49] H. M. Zhang, A non-equilibrium traffic model devoid of gas-like behavior, Transportation Research, B., 36 (2002), 275-290. doi: 10.1016/S0191-2615(00)00050-3
    [50] H. M. Zhang, Driver memory, traffic viscosity and a viscous vehicular traffic flow model, Transportation Research, B., 37 (2003), 27-41.
  • This article has been cited by:

    1. Zhiguo Qu, Yiming Huang, Min Zheng, A novel coherence-based quantum steganalysis protocol, 2020, 19, 1570-0755, 10.1007/s11128-020-02868-2
  • Reader Comments
  • © 2013 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)
通讯作者: 陈斌, bchen63@163.com
  • 1. 

    沈阳化工大学材料科学与工程学院 沈阳 110142

  1. 本站搜索
  2. 百度学术搜索
  3. 万方数据库搜索
  4. CNKI搜索

Metrics

Article views(5283) PDF downloads(1322) Cited by(1)

Other Articles By Authors

/

DownLoad:  Full-Size Img  PowerPoint
Return
Return

Catalog