A novel quantum image steganography algorithm based on exploiting modification direction

Multimedia Tools and Applications - Quantum image steganography is the art and science of hiding secret information into quantum carrier images. This paper proposes a novel quantum image...     

Quantum convolutional neural network for image classification

Pattern Analysis and Applications - In this paper we propose two scale-inspired local feature extraction methods based on Quantum Convolutional Neural Network (QCNN) in the Tensorflow quantum...     

Quantum hopping techniques applied to vibrational energy transfer

Mixed quantum/classical methods applied to vibrational energy exchange are presented. Vibrational MDQT is based on the Tully's Molecular Dynamics with Quantum Transitions with the quantal degrees of freedom represented in a diabatic spectral basis. MQCS is similar in spirit but it uses a Discrete Variable Representation (DVR) of the quantum degrees of freedom. Applications include vibrational predissociation in van der Waals complexes and vibrational energy exchange in atom surface collisions.     

Qubit state discrimination using post-measurement information

Quantum Information Processing - We investigate classical and quantum geometric information flow theories (GIFs and QGIFs) when the geometric flow evolution and field equations for nonholonomic...     

Geometry of quantum state space and quantum correlations

Quantum state space is endowed with a metric structure, and Riemannian monotone metric is an important geometric entity defined on such a metric space. Riemannian monotone metrics are very useful for information-theoretic and statistical considerations on the quantum state space. In this article, considering the quantum state space being spanned by \(2\times 2\) density matrices, we determine a particular Riemannian metric for a state \(\rho \) and show that if \(\rho \) gets entangled with another quantum state, the negativity of the generated entangled state is, upto a constant factor, equal to square root of that particular Riemannian metric . Our result clearly relates a geometric quantity to a measure of entanglement. Moreover, the result establishes the possibility of understanding quantum correlations through geometric approach.     

Quantum correlation via quantum coherence

Quantum correlation includes quantum entanglement and quantum discord. Both entanglement and discord have a common necessary condition—quantum coherence or quantum superposition. In this paper, we attempt to give an alternative understanding of how quantum correlation is related to quantum coherence. We divide the coherence of a quantum state into several classes and find the complete coincidence between geometric (symmetric and asymmetric) quantum discords and some particular classes of quantum coherence. We propose a revised measure for total coherence and find that this measure can lead to a symmetric version of geometric quantum correlation, which is analytic for two qubits. In particular, this measure can also arrive at a monogamy equality on the distribution of quantum coherence. Finally, we also quantify a remaining type of quantum coherence and find that for two qubits, it is directly connected with quantum nonlocality.     

Ordering states with various coherence measures

Quantum coherence is one of the most significant theories in quantum physics. Ordering states with various coherence measures is an intriguing task in quantification theory of coherence. In this paper, we study this problem by use of four important coherence measures—the \(l_1\) norm of coherence, the relative entropy of coherence, the geometric measure of coherence and the modified trace distance measure of coherence. We show that each pair of these measures give a different ordering of qudit states when \(d\ge 3\). However, for single-qubit states, the \(l_1\) norm of coherence and the geometric coherence provide the same ordering. We also show that the relative entropy of coherence and the geometric coherence give a different ordering for single-qubit states. Then we partially answer the open question proposed in Liu et al. (Quantum Inf Process 15:4189, 2016) whether all the coherence measures give a different ordering of states.     

一种新的量子群进化算法研究

提出了一种基于量子进化的量子群进化算法，使用量子角表示量子比特的状态，并引入改进的粒子群优化策略，对量子群中各量子的量子角进行自适应动态调整．在对0-1背包问题的求解中，表现出很好的性能．     

Multi-qubit non-adiabatic holonomic controlled quantum gates in decoherence-free subspaces

Non-adiabatic holonomic quantum gate in decoherence-free subspaces is of greatly practical importance due to its built-in fault tolerance, coherence stabilization virtues, and short run-time. Here, we propose some compact schemes to implement two- and three-qubit controlled unitary quantum gates and Fredkin gate. For the controlled unitary quantum gates, the unitary operator acting on the target qubit is an arbitrary single-qubit gate operation. The controlled quantum gates can be directly implemented by utilizing non-adiabatic holonomy in decoherence-free subspaces and the required resource for the decoherence-free subspace encoding is minimal by using only two neighboring physical qubits undergoing collective dephasing to encode a logical qubit.     

Crop art, part 3

For Part 2 see ibid., vol.24, no.6 (2004). The article finishes a three-part series on crop circles and crop formations. Part 1 (see ibid., vol.24, no.5, 2004) talked about the history of crop circles, and the people who make and study them. The author also presented the strange story of the five Hawkins Theorems, and showed how to construct the basic geometrical skeleton for a crop design. In Part 2 the author presented his Crop language for representing many crop patterns in a compact form. The author discusses an original design made using Crop, and tells the story of how that design was created.     

非线性系统的几何方法（上） 几何方法与几何基础

本文介绍控制理论的一个新的分支——非线性系统的几何理论。第一部分包括:几何理论的特点和分析方法,几何基础以及非线性系统是如何用几何方法来描述的。第二部分介绍几何理论的现状;主要研究方向,进展情况以及尚待解决的问题。最后,根据目前的动态对今后的主要发展趋势作一些分析和预测。     

The $$H_2$$ H 2 -reducible matrix in four six-dimensional mutually unbiased bases

Quantum Information Processing - Quantum router is an essential ingredient in a quantum network. Here, we propose a new quantum circuit for designing quantum router by using IBM’s five-qubit...     

量子遗传算法在TSP中的应用

本文提出了一种改进的量子遗传算法,其核心是对量子遗传算法中的量子旋转门的调整策略进行改进。在现有的静态、指数型动态调整策略的基础上提出了基于正弦函数的动态调整策略。文中对旅行商问题（TSP）的仿真实验结果表明：改进后的算法的优化质量和效率都优于遗传算法和一般量子遗传算法。     

量子隐形传态原理及其MATLAB仿真

由于没有操纵量子比特的条件,MATLAB成为通信工程人员和在校学生学习量子通信基本原理的良好工具。文章给出了量子隐形传态的概念,分析了量子隐形传态原理。编写了量子隐形传态的仿真程序。给出了量子交换机仿真程序的核心部分代码。     

Uncertainty-like relations of the relative entropy of coherence

Quantum Information Processing - Quantum coherence is an important physical resource in quantum computation and quantum information processing. In this paper, we firstly obtain an uncertainty-like...     

Geometric measure of quantum discord for a two-parameter class of states in a qubit–qutrit system under various dissipative channels

Quantum discord, as a measure of all quantum correlations, has been proposed as the key resource in certain quantum communication tasks and quantum computational models without containing much entanglement. Daki? et al. (Phys Rev Lett 105:190502, 2010) introduced a geometric measure of quantum discord (GMQD) and derived an explicit formula for any two-qubit state. Luo and Fu (Phys Rev A 82:034302, 2010) introduced another form of GMQD and derived an explicit formula for arbitrary state in a bipartite quantum system. However, the explicit analytical expression for any bipartite system was not given. In this work, we give out the explicit analytical expressions of the GMQD for a two-parameter class of states in a qubit–qutrit system and study its dynamics for the states under various dissipative channels in the first time. Our results show that all these dynamic evolutions do not lead to a sudden vanishing of GMQD. Quantum correlations vanish at an asymptotic time for local or multi-local dephasing, phase-flip, and depolarizing noise channels. However, it does not disappear even though t → ∞ for local trit-flip and local trit-phase-flip channels. Our results maybe provide some important information for the application of GMQD in hybrid qubit–qutrit systems in quantum information.     

Quantum effects near the big rip revisited

Quantum effects near a big rip singularity have been investigated previously, with the conclusion that the energy due to these quantum effects decreases as the future singularity is approached. Hence, backreaction due to quantum effects would not prevent a big rip singularity. That calculation was performed by introducing an ultraviolet cut-off. In the present work, we consider the energy-momentum tensor of a minimally coupled massless scalar field, obtaining a different expression for the backreaction after reguralization. No ultraviolet cutoff is introduced. The new expression seems to indicate that quantum effects may be dominant as the singularity is approached.     

Fidelity of Gaussian Channels

A noisy Gaussian channel is defined as a channel in which an input field mode is subjected to random Gaussian displacements in phase space. We introduce the quantum fidelity of a Gaussian channel for pure and mixed input states, and we derive a universal scaling law of the fidelity for pure initial states. We also find the maximum fidelity of a Gaussian channel over all input states. Quantum cloning and continuous-variable teleportation are presented as physical examples of Gaussian channels to which the fidelity results can be applied.Presented at the 36th Symposium on Mathematical Physics, “Open Systems & Quantum Information”, Toruń, Poland, June 9–12, 2004.Supported in part by US O.ce of Naval Research Grant No. N00014–03–1–0426.Supported in part by KBN Grant No. PBZ–Min–008/P03/03     

Quantum information approach to the azurite mineral frustrated quantum magnet

Quantum correlations are almost impossible to address in bulk systems. Quantum measures extended only to a few number of parties can be discussed in practice. In the present work, we study nonlocality for a cluster of spins belonging to a mineral whose structure is that of a quantum magnet. We reproduce at a much smaller scale the experimental outcomes, and then, we study the role of quantum correlations there. A macroscopic entanglement witness has been introduced in order to reveal nonlocal quantum correlations between individual constituents of the azurite mineral at nonzero temperatures. The critical point beyond which entanglement is zero is found at \(T_c < 1\,\mathrm{K}\).     

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete-time quantum walks.