The relation between Hardy’s non-locality and violation of Bell inequality

We give an analytic quantitative relation between Hardy’s non-locality and Bell operator. We find that Hardy’s non-locality is a sufficient condition for the violation of Bell inequality, the upper bound of Hardy’s non-locality allowed by information causality just corresponds to Tsirelson bound of Bell inequality and the upper bound of Hardy’s non-locality allowed by the principle of no-signaling just corresponds to the algebraic maximum of Bell operator. Then we study the Cabello’s argument of Hardy’s non-locality (a generalization of Hardy’s argument) and find a similar relation between it and violation of Bell inequality. Finally, we give a simple derivation of the bound of Hardy’s non-locality under the constraint of information causality with the aid of the above derived relation between Hardy’s non-locality and Bell operator.     

Time and Causality: A Thermocontextual Perspective

The thermocontextual interpretation (TCI) is an alternative to the existing interpretations of physical states and time. The prevailing interpretations are based on assumptions rooted in classical mechanics, the logical implications of which include determinism, time symmetry, and a paradox: determinism implies that effects follow causes and an arrow of causality, and this conflicts with time symmetry. The prevailing interpretations also fail to explain the empirical irreversibility of wavefunction collapse without invoking untestable and untenable metaphysical implications. They fail to reconcile nonlocality and relativistic causality without invoking superdeterminism or unexplained superluminal correlations. The TCI defines a system’s state with respect to its actual surroundings at a positive ambient temperature. It recognizes the existing physical interpretations as special cases which either define a state with respect to an absolute zero reference (classical and relativistic states) or with respect to an equilibrium reference (quantum states). Between these special case extremes is where thermodynamic irreversibility and randomness exist. The TCI distinguishes between a system’s internal time and the reference time of relativity and causality as measured by an external observer’s clock. It defines system time as a complex property of state spanning both reversible mechanical time and irreversible thermodynamic time. Additionally, it provides a physical explanation for nonlocality that is consistent with relativistic causality without hidden variables, superdeterminism, or “spooky action”.     

Information Theoretic Causality Detection between Financial and Sentiment Data

The interaction between the flow of sentiment expressed on blogs and media and the dynamics of the stock market prices are analyzed through an information-theoretic measure, the transfer entropy, to quantify causality relations. We analyzed daily stock price and daily social media sentiment for the top 50 companies in the Standard & Poor (S&P) index during the period from November 2018 to November 2020. We also analyzed news mentioning these companies during the same period. We found that there is a causal flux of information that links those companies. The largest fraction of significant causal links is between prices and between sentiments, but there is also significant causal information which goes both ways from sentiment to prices and from prices to sentiment. We observe that the strongest causal signal between sentiment and prices is associated with the Tech sector.     

Thermal entanglement and teleportation of a thermally mixed entangled state of a Heisenberg chain through a Werner state

The thermal entanglement and teleportation of a thermally mixed entangled state of a two-qubit Heisenberg XXX chain under the Dzyaloshinski Moriya （DM） anisotropic antisymmetric interaction through a noisy quantum channel given by a Werner state is investigated. The dependences of the thermal entanglement of the teleported state on the DM coupling constant, the temperature and the entanglement of tbe noisy quantum channel are studied }n detail for both the ferromagnetic and the antiferromagnetic cases. The result shows that a minimum entanglement of the noisy quantum channel must be provided in order to realize the entanglement teleportation. The values of fidelity of the teleported state are also studied for these two cases. It is found that under certain conditions, we can transfer an initial state with a better fidelity than that for any classical communication protocol.     

陆续通过一个双模腔的两原子之间纠缠的突然产生和调控

通过计算并发度研究了陆续通过一个双模腔的两个原子之间的纠缠动力学特性, 讨论了第一个原子的相干性以及腔场初始纠缠度对两原子之间纠缠的影响. 结果表明系统在一定条件下可以出现两原子之间纠缠突然产生现象, 两原子之间产生纠缠的最大值依赖于双模腔场初始纠缠度; 并且可以通过改变原子的振幅来控制产生纠缠的阈值时间和纠缠的最大值, 理论上提供了一种调控纠缠的方式.     

The Effect of a Hidden Source on the Estimation of Connectivity Networks from Multivariate Time Series

Many methods of Granger causality, or broadly termed connectivity, have been developed to assess the causal relationships between the system variables based only on the information extracted from the time series. The power of these methods to capture the true underlying connectivity structure has been assessed using simulated dynamical systems where the ground truth is known. Here, we consider the presence of an unobserved variable that acts as a hidden source for the observed high-dimensional dynamical system and study the effect of the hidden source on the estimation of the connectivity structure. In particular, the focus is on estimating the direct causality effects in high-dimensional time series (not including the hidden source) of relatively short length. We examine the performance of a linear and a nonlinear connectivity measure using dimension reduction and compare them to a linear measure designed for latent variables. For the simulations, four systems are considered, the coupled Hénon maps system, the coupled Mackey–Glass system, the neural mass model and the vector autoregressive (VAR) process, each comprising 25 subsystems (variables for VAR) at close chain coupling structure and another subsystem (variable for VAR) driving all others acting as the hidden source. The results show that the direct causality measures estimate, in general terms, correctly the existing connectivity in the absence of the source when its driving is zero or weak, yet fail to detect the actual relationships when the driving is strong, with the nonlinear measure of dimension reduction performing best. An example from finance including and excluding the USA index in the global market indices highlights the different performance of the connectivity measures in the presence of hidden source.     

Time evolution law of a two-mode squeezed light field passing through twin diffusion channels

We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,which shows that even though the two channels are independent of each other,since the two modes of the initial state are entangled with each other,the final state remains entangled.Nevertheless,although the squeezing(entanglement)between the two modes is weakened after the diffusion,it is not completely removed.We also highlight the law of photon number evolution.In the calculation process used in this paper,we make full use of the summation method within the ordered product of operators and the generating function formula for two-variable Hermite polynomials.     

纠缠的纯化和提取

纠缠的纯化和提取在量子信息的理论和实验上都是一个重要的方向，简单回顾了这个方向上的一些主要进展，并重点介绍了有限个拷贝情况下的纠缠提取。提出了准分离态和提取子空间的概念，得到了从一个混合态的有限个拷贝中提取纯纠缠态的必要条件及充要条件；并得到了有限个拷贝情况下的最有效的提取方案；考虑了这些结论在无限个拷贝的情况下的推广。     

Remote preparation of atomic and field cluster states from a pair of tri-partite GHZ states

We propose two simple and resource-economical schemes for remote preparation of four-partite atomic as well as cavity field cluster states.In the case of atomic state generation,we utilize simultaneous resonant and dispersive interactions of the two two-level atoms at the preparation station.Atoms involved in these interactions are individually pair-wise entangled into two different tri-partite GHZ states.After interaction,the passage of the atoms through a Ramsey zone and their subsequent detection completes the protocol.However,for field state generation we first copy the quantum information in the cavities to the atoms by resonant interactions and then adapt the same method as in the case of atomic state generation.The method can be generalised to remotely generate any arbitrary graph states in a straightforward manner.     

Risk Transmission of Trade Price Fluctuations from a Nickel Chain Perspective: Based on Systematic Risk Entropy and Granger Causality Networks

Nickel is a strategic mineral resource, with 65% of nickel being used in stainless steel. The situation in Ukraine starting in February 2022 has led to significant fluctuations in nickel prices, with prices of nickel products along the same chain affecting and passing through each other. Using systematic risk entropy and granger causality networks, we measure the volatility risk of trade prices of nickel products using the nickel industry chain trade data from 2000–2019 and explore the transmission patterns of different volatility risk prices from the industry chain perspective. The findings show that: (1) Nickel ore has the highest risk of import trade price volatility and a strong influence, but low risk transmission. Stainless steel has the highest trade price impact but is also subject to the strongest passive influence. (2) The Americas have a higher risk of trade price volatility but a weaker influence. The influence and sensitivity of trade prices is stronger in Asia and Europe. (3) Indonesia’s stainless steel export prices have a high rate of transmission and strong influence. Germany’s ferronickel export prices are highly susceptible to external influences and can continue to spread loudly. Russian nickel ore export prices are able to quickly spread their impact to other regions.     

量子信息科学在中国科学技术大学的兴起和发展

文章介绍了中国科学技术大学的量子信息科学研究是如何兴起和发展的;着重介绍了在量子信息的基础理论、量子密码、量子纠缠、量子隐形传态、量子处理器和量子信息的应用等方面所取得的研究成果.     

The Role of Entanglement in Quantum Measurement and Information Processing

The significance of the quantum feature of entanglement between physical systems is investigated in the context of quantum measurements. It is shown that, while there are measurement couplings that leave the object and probe systems nonentangled, no information transfer from object to probe can take place unless there is at least some intermittent period where the two systems are entangled.     

The Matter of Time

About a century ago, in the spirit of ancient atomism, the quantum of light was renamed the photon to suggest that it is the fundamental element of everything. Since the photon carries energy in its period of time, a flux of photons inexorably embodies a flow of time. Thus, time comprises periods as a trek comprises legs. The flows of quanta naturally select optimal paths (i.e., geodesics) to level out energy differences in the least amount of time. The corresponding flow equations can be written, but they cannot be solved. Since the flows affect their driving forces, affecting the flows, and so on, the forces (i.e., causes) and changes in motions (i.e., consequences) are inseparable. Thus, the future remains unpredictable. However, it is not all arbitrary but rather bounded by free energy. Eventually, when the system has attained a stationary state where forces tally, there are no causes and no consequences. Since there are no energy differences between the system and its surroundings, the quanta only orbit on and on. Thus, time does not move forward either but circulates.     

The Necessary and Sufficient Conditions for a Universal Conservation of a State of a Unitary Quantum Circuit

By A. Peres and A. Stern‘s opinions a computational process evolves along a cyclic logic orbit defined by a computation. A. Stern thought that if we could design such a circuit, its operations can be extended to including nonconservative behavior associated with the external perturbations or internal quantum errors. A. Peres did not discuss how to make φM-1 ＝φo. A. Stern proposed only a necessary condition for a conservation of a state of a quantum circuit.In this paper we present a necessary and sufficient condition for a universal conservation of a state of a quantum circuit.We also find all operators which can allow the conservation.     

The Necessary and Sufficient Conditions for a Universal Conservation of a State of a Unitary Quantum Circuit

By A. Peres and A. Stern's opinions a computational process evolves along a cyclic logic orbit defined by the sequence ψ₀→ψ₁→ … →ψ_M-1→ψ₀. It begins from a start position and returns to the same position after a computation. A. Stern thought that if we could design such a circuit, its operations can be extended to including nonconservative behavior associated with the external perturbations or internal quantum errors. A. Peres did not discuss how to make φ_M-1=φ₀. A. Stern proposed only a necessary condition for a conservation of a state of a quantum circuit. In this paper we present a necessary and sufficient condition for a universal conservation of a state of a quantum circuit. We also find all operators which can allow the conservation.     

粒子穿越势阱及光子穿过薄玻璃板时的能速及渡越时间

采用一与电磁波场中能速概念含义相似的物理速度－能量运动速度（简称能速）来描述量子力学中粒子穿越势阱过程,此能速对应的粒子渡越时间和相位时间相比,不存在负值现象。此能速同样可以用来描述光学中光子穿过非色散薄玻璃板介质时的过程,和相应的相位时间相比,此能速对应的光子渡越时间也不存在负值现象。给出了实验上测量光子渡越时间的方法。     

The stopped‐drop method: a novel setup for containment‐free and time‐resolved measurements

A novel setup for containment‐free time‐resolved experiments at a free‐hanging drop is reported. Within a dead‐time of 100 ms a drop of mixed reactant solutions is formed and the time evolution of a reaction can be followed from thereon by various techniques. As an example, a small‐angle X‐ray scattering study on the formation mechanism of EDTA‐stabilized CdS both at a synchrotron and a laboratory X‐ray source is presented here. While the evolution can be followed with one drop only at a synchrotron source, a stroboscopic mode with many drops is preferable for the laboratory source.     

Nonequilibrium free energy and information flow of a double quantum-dot system with Coulomb coupling

We build a double quantum-dot system with Coulomb coupling and aim at studying connections among the entropy production, free energy, and information flow. By utilizing concepts in stochastic thermodynamics and graph theory analysis, Clausius and nonequilibrium free energy inequalities are built to interpret local second law of thermodynamics for subsystems. A fundamental set of cycle fluxes and affinities is identified to decompose two inequalities by using Schnakenberg's network theory. Results show that the thermodynamic irreversibility has energy-related and information-related contributions. A global cycle associated with the feedback-induced information flow would pump electrons against the bias voltage, which implements a Maxwell demon.