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Quantum random number generator (QRNG) relies on the intrinsic randomness of quantum mechanics to produce true random numbers which are important in information processing tasks. Due to the presence of the superposition state, a quantum computer can be used as a true random number generator. However, in practice, the implementation of the quantum computer is subject to various noise sources, which affects the randomness of the generated random numbers. To solve this problem, we propose a scheme based on the quantum computer which is motivated by the source-independent QRNG scheme in optics. By using a method to estimate the upper bound of the superposition state preparation error, the scheme can provide certified randomness in the presence of readout errors. To increase the generation rate of random bits, we also provide a parameter optimization method with a finite data size. In addition, we experimentally demonstrate our scheme on the cloud superconducting quantum computers of IBM. [ABSTRACT FROM AUTHOR]

Quantum random number generator (QRNG) relies on the intrinsic randomness of quantum mechanics to produce true random numbers which are important in many fields, such as cryptographic protocols, security applications and Monte Carlo simulations. Recently, QRNGs with semiconductor light source have attracted a lot of attention due to their operational simplicity and high generation rate. However, the output characteristics of the light source in QRNG may be affected by temperature variations, which impacts the performance of QRNG. In this work, we study the effects of temperature increase on the super-luminescent emitting diode (SLED)-based QRNG with a numerical method. The results show that the temperature increase in SLED leads to the decrease of min-entropy. When the temperature is higher than some threshold value, the output sequence cannot pass the NIST Statistical Test. Our analysis also shows that the QRNG can be more robust by improving the post-processing method and monitoring the temperature as well as the min-entropy and thus provides a reference for the standardization of QRNG. [ABSTRACT FROM AUTHOR]

Based on the intrinsic randomness of quantum mechanics, quantum random number generators (QRNGs) can produce true random numbers in theory. However, in realistic scenarios, the physical devices of QRNGs may have imperfections or be controlled by some malicious parties, which threatens the security of QRNGs. We experimentally study the security of superluminescent LED (SLED)-based QRNGs under different working conditions. The experimental results show that the output characteristics and performance of the QRNG are affected by the temperature and drive current variations. The higher the drive current of SLED, the greater the influence of temperature variation on the security of the QRNG. Therefore, it is important for the user to choose an appropriate current to drive the QRNG. In addition, our analysis also shows that the QRNG can be more robust by improving the postprocessing method and by monitoring the output optical power as well as the minimum entropy. Thus, this work provides a reference for the standardization of QRNGs. [ABSTRACT FROM AUTHOR]

The finite-key security of the standard three-intensity decoy-state quantum key distribution (QKD) protocol in the presence of information leakage has been analyzed (Wang et al. in New J Phys 20:083027, 2018). On the other hand, the 1-decoy state QKD protocol has been proved to be able to achieve higher secret key rate than the three-intensity decoy-state QKD protocol in the finite-key regime by using only two different intensity settings (Davide et al. in Appl Phys Lett 112:171104, 2018). In this work, we analyze the finite-key security of the 1-decoy state QKD protocol with a leaky intensity modulator, which is used to generate the decoy state. In particular, we simulate the secret key rate under three practical cases of Trojan-horse attacks. Our simulation results demonstrate that the 1-decoy state QKD protocol can be secure over long distances within a reasonable time frame given that the intensity modulator is sufficiently isolated. By comparing the simulation results to those presented in Wang et al. (2018), we find that, as expected, the 1-decoy state QKD protocol is more robust against information leakage from the intensity modulator for all achievable distances. [ABSTRACT FROM AUTHOR]

The variational quantum algorithm (VQA) is a hybrid classical–quantum algorithm. It can actually run in an intermediate-scale quantum device where the number of available qubits is too limited to perform quantum error correction, so it is one of the most promising quantum algorithms in the noisy intermediate-scale quantum era. In this paper, two ideas for solving the learning with errors problem (LWE) using VQA are proposed. First, after reducing the LWE problem into the bounded distance decoding problem, the quantum approximation optimization algorithm (QAOA) is introduced to improve classical methods. Second, after the LWE problem is reduced into the unique shortest vector problem, the variational quantum eigensolver (VQE) is used to solve it, and the number of qubits required is calculated in detail. Small-scale experiments are carried out for the two LWE variational quantum algorithms, and the experiments show that VQA improves the quality of the classical solutions. [ABSTRACT FROM AUTHOR]

In this paper, we consider the optimization of the quantum circuit for discrete logarithm of binary elliptic curves under a constrained connectivity, focusing on the resource expenditure and the optimal design for quantum operations such as the addition, binary shift, multiplication, squaring, inversion, and division included in the point addition on binary elliptic curves. Based on the space-efficient quantum Karatsuba multiplication, the number of CNOTs in the circuits of inversion and division has been reduced with the help of the Steiner tree problem reduction. The optimized size of the CNOTs is related to the minimum degree of the connected graph. [ABSTRACT FROM AUTHOR]

Solving algebraic equations over GF(2) is a problem which has a wide range of applications, including NP-Hard problems and problems related to cryptography. The existing mature algorithms are difficult to solve large-scale problems. Inspired by Schöning's algorithm and its quantum version, we apply related methods to solve algebraic equations over GF (2). The new algorithm we proposed has a significant improvement of solving efficiency in large-scale and sparse algebraic equations. As a hybrid algorithm, the new algorithm can not only run on a classic computer alone, but also use small-scale quantum devices to assist acceleration. And the new algorithm can be seen as an example of solving a large-scale problem on a small-scale quantum device. [ABSTRACT FROM AUTHOR]