Active phase compensation of quantum key distribution system

Chen, Wei; Han, Zheng‐Fu; Mo, Xinxin; Xu, F.; Guo, Wei; Guo, Guang‐Can

doi:10.1007/s11434-008-0023-0

Cited by 38 publications

(24 citation statements)

References 17 publications

(22 reference statements)

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“…9 (Chen, et al, 2008). Generally, there are three methods to solve the problem: Modify the structure of interferometers such as "plugand-play" configuration to auto-compensate the phase shift.…”

Section: Phase Drift Compensationmentioning

confidence: 99%

Quantum Cryptography

Chen¹,

Li²,

Wang³

et al. 2012

Applied Cryptography and Network Security

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Section: Phase Drift Compensationmentioning

confidence: 99%

Quantum Cryptography

Chen¹,

Li²,

Wang³

et al. 2012

Applied Cryptography and Network Security

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“…Phase drift is an inherent problem in a phase-encoded QKD system [9]. To quantitatively measure the phase drift in our present QKD system, we carried out the following experiment.…”

Section: Phase Drift In the Phase-encoded Qkd Systemmentioning

confidence: 99%

“…Current investigations on phase drift and compensation [8,9] assume that the control voltage of the phase modulator has a linear relationship with the actual phase change in the interferometer (these are known as single-phase scanning solutions). For those systems that do not have a linear relationship between the control voltage and phase change, the effectiveness of the single-phase scanning is very limited.…”

mentioning

confidence: 99%

“…For those systems that do not have a linear relationship between the control voltage and phase change, the effectiveness of the single-phase scanning is very limited. During the actual testing of a multi-node QKD network in our laboratory [10,11], we also found that the v-φ relation for some modulators is not linear [9,[12][13][14], which means that a new phase tracking and compensation method has to be researched. In addition, besides the optical phase modulator, the control electronics system also contributes to the nonlinearity of the system, which includes the nonlinearity of the digital-to-analog converter, voltage signal amplification, and so on.…”

mentioning

confidence: 99%

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Real-time compensation of phase drift for phase-encoded quantum key distribution systems

et al. 2011

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Phase drift is an inherent problem in phase-encoded quantum key distribution (QKD) systems. The current active phase tracking and compensation solutions cannot satisfy the requirements of a system with nonlinearity in phase modulation. This paper presents a four-phase scanning method, which is based on the quantitative analysis of the quantum bit error rate (QBER) from phase drift and the performance requirements of phase compensation. By obtaining the four interference fringes and adjusting the coding matrix of the system, this method automatically calculates the accurate driving voltages for the phase modulator. The implementation and experimental tests show that the proposed method can compensate phase drift caused by environmental changes and the system's nonlinearity, and is applicable to large-scale QKD networks. Quantum key distribution (QKD) offers a secure way of separating parties to establish a shared cryptographic key over a non-protected communication channel. The first quantum cryptography protocol, BB84 [1], defined by Bennett and Brassard in 1984, makes it possible to implement the one-time-pad encryption in practice. This has attracted the attention of many researchers in the field of information security. Following the developments over the past two decades, QKD systems have progressed from laboratory studies to applicable commercial products. Optical fiber based QKD systems using optical fiber to provide the quantum transmission channel, encode the bit information using the quantum states of single photons. Most early optical fiber based QKD systems used the polarization coding scheme [2]. This scheme can easily be realized in a laboratory, but it is not the best choice for fiber based QKD systems because of the inherent birefringence effect on the single-mode fiber. The birefringence effect can destroy the polarization states of photons, causing a higher quantum bit error rate (QBER) as the transmission distance increases [3,4].The phase coding scheme is the scheme of choice for current implementations of fiber based QKD systems [5,6]. With an interferometer pair on the two communication sides, the sender (Alice) encodes the bit information as a phase delay in the interferometer and the receiver (Bob) decodes the phase delay to obtain the transmitted information. Figure 1 shows the structure of an asymmetric FaradayMichelson interferometer (F-MI) QKD system [7]. There are two F-M interferometers located on either side of Alice and Bob which are connected by an optical fiber. Photons emitted by the sender can follow one of two paths when passing through the interferometers at both sender and receiver -one path is the short arm in the interferometer and the other is the long arm. Therefore, the counting histogram of the single photon detector (SPD) in Bob will have three peaks. The first peak corresponds to the 'short-short' path, the last peak corresponds to the 'long-long' path, and

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“…In 1996, Grover [2] presented a quantum searching algorithm that reduces the computational complexity of current exhaustive search attacks from O(2 n ) to O(2 n/2 ). To overcome this problem, scholars [3][4][5][6][7][8][9][10][11] in China and abroad have since intensively investigated quantum computation and quantum cryptology. Although the correctness of quantum computation and Shor's algorithm has been proved to hold true [12], it is still difficult to break 2048-bit RSA or 191-bit ECC in the case of the quantum computer for the reason that the kilobit quantum computer does not exist.…”

mentioning

confidence: 99%

t-bit semiclassical quantum Fourier transform

Bao

Zhou

et al. 2012

Chin. Sci. Bull.

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Because of the difficulty of building a high-dimensional quantum register, this paper presents an implementation of the high-dimensional quantum Fourier transform (QFT) based on a low-dimensional quantum register. First, we define the t-bit semiclassical quantum Fourier transform. In terms of probability amplitude, we prove that the transform can realize quantum Fourier transformation, illustrate that the requirement for the two-qubit gate reduces obviously, and further design a quantum circuit of the transform. Combining the classical fixed-window method and the implementation of Shor's quantum factorization algorithm, we then redesign a circuit for Shor's algorithm, whose required computation resource is approximately equal to that of Parker's. The requirement for elementary quantum gates for Parker's algorithm is , and the quantum register for our circuit requires t1 more dimensions than Parker's. However, our circuit is t 2 times as fast as Parker's, where t is the width of the window. Quantum computing has a strong ability for parallel computing, which poses a great challenge to the security of the modern cipher. In 1994, Shor [1] presented a polynomial-time quantum algorithm for factorization. Apparently, the emergence of this algorithm greatly threatens the public-key cryptography, such as RSA cryptography, whose security is based on factorization and a discrete logarithm. In 1996, Grover [2] presented a quantum searching algorithm that reduces the computational complexity of current exhaustive search attacks from O(2 n ) to O(2 n/2 ). To overcome this problem, scholars [3][4][5][6][7][8][9][10][11] in China and abroad have since intensively investigated quantum computation and quantum cryptology. Although the correctness of quantum computation and Shor's algorithm has been proved to hold true [12], it is still difficult to break 2048-bit RSA or 191-bit ECC in the case of the quantum computer for the reason that the kilobit quantum computer does not exist. Thus, how to reduce the computation resource required for Shor's algorithm is an issue of common concern.In 1996, Vedral et al.[13] published a circuit with a 7n+1-dimensional quantum register and O(n 3 ) elementary gates for modular exponentiation (where n denotes the length of the integer to be factorized). It has been mentioned that the quantum register requirement can be reduced to 4n+3 if unbounded Toffoli gates (n-controlled NOT gates) are available. Also in 1996, Beckman et al. [14] presented an extended analysis of modular exponentiation, with a circuit of a 4n+1-dimensional quantum register if unbounded Toffoli gates are available. In 1998, Zalka [15] described a method for factorization with a 3n+O(logN)-dimensional quantum register using only elementary gates. However, these achievements are the optimization of Shor's algorithm, which is based only on reducing the dimensions of the quantum register.Generally speaking, in the implementation of the quantum Fourier transform (QFT), the n-bit quantum state is once inputted into a n-dimensional...

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Active phase compensation of quantum key distribution system

Cited by 38 publications

References 17 publications

Quantum Cryptography

Quantum Cryptography

Real-time compensation of phase drift for phase-encoded quantum key distribution systems

t-bit semiclassical quantum Fourier transform

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