On the Origin of Entropic Gravity and Inertia

It was recently suggested that quantum field theory is not fundamental but emerges from the loss of phase space information about matter crossing causal horizons. Possible connections between this formalism and Verlinde’s entropic gravity and Jacobson’s thermodynamic gravity are proposed. The holographic screen in Verlinde’s formalism can be identified as local Rindler horizons and its entropy as that of the bulk fields beyond the horizons. This naturally resolves some issues on entropic gravity. The quantum fluctuation of the fields is the origin of the thermodynamic nature of entropic gravity. It is also suggested that inertia is related to dragging Rindler horizons.     

Time-Symmetric Quantization in Spacetimes with Event Horizons

The standard quantization formalism in spacetimes with event horizons implies a non-unitary evolution of quantum states, as initial pure states may evolve into thermal states. This phenomenon is behind the famous black hole information loss paradox which provoked long-standing debates on the compatibility of quantum mechanics and gravity. In this paper we demonstrate that within an alternative time-symmetric quantization formalism thermal radiation is absent and states evolve unitarily in spacetimes with event horizons. We also discuss the theoretical consistency of the proposed formalism. We explicitly demonstrate that the theory preserves the microcausality condition and suggest a “reinterpretation postulate” to resolve other apparent pathologies associated with negative energy states. Accordingly as there is a consistent alternative, we argue that choosing to use time-asymmetric quantization is a necessary condition for the black hole information loss paradox.     

量子信息研究进展

量子信息论是经典信息论与量子力学相结合的新兴交叉学科。本文综述了量子信息领域的研究进展。即包括了为人们所熟知的量子通信与量子计算领域 ,也包括了刚刚兴起的但却有巨大潜力的量子对策论等领域。本文以介绍量子信息论的基本理论框架为主 ,同时也介绍了量子信息领域的实验研究进展。     

量子信息研究进展

量子信息论是经典信息论与量子力学相结合的新兴交叉学科,本综述了最子信息领域的研究进展。即包括了为人们所熟知的量子通信与量子计算领域,也包括了刚刚兴起的但却有巨大潜力的量子对策论等领域。本以介绍量子信息论的基本理论框架为主,同时也介绍了量子信息领域的实验研究进展。     

Process Physics: Inertia, Gravity and the Quantum

Process Physics models reality as self-organising relational or semantic information using a self-referentially limited neural network model. This generalises the traditional non-process syntactical modelling of reality by taking account of the limitations and characteristics of self-referential syntactical information systems, discovered by Gödel and Chaitin, and the analogies with the standard quantum formalism and its limitations. In process physics space and quantum physics are emergent and unified, and time is a distinct non-geometric process. Quantum phenomena are caused by fractal topologicaldefects embedded in and forming a growing three-dimensional fractal process-space. Various features of the emergent physics are briefly discussed including:quantum gravity, quantum field theory, limited causality and the Born quantum measurement metarule, inertia, time-dilation effects, gravity and the equivalence principle, a growing universe with a cosmological constant, black holes and event horizons, and the emergence of classicality.     

量子理论若干基本问题研究的新进展

本文结合最近的典型量子物理实验 ,如用冷原子Bragg散射实现的“which way”实验 ,量子退相干过程的微腔QED检验和C60 分子的量子干涉等 ,比较系统地介绍了量子理论基本问题若干研究的新进展 ,特别强调了处于其核心的量子测量问题及其相关的基本概念和基本思想 ,如EPR佯谬和Bell不等式 ,量子退相干和量子纠缠。从理论和实验结合的角度 ,本文阐述了被测系统和测量仪器的相互作用怎样导致量子测量的一般动力学过程。由此还讨论了外部环境和内部运动怎样诱导量子退相干和量子耗散 ,对“薛定谔猫佯谬”和“宏观物体空间局域化描述”给出了可能的物理解释。最后 ,通过具体例子 ,本文简单地讨论了量子物理基本问题的研究结果对量子信息的应用     

量子理论若干基本问题研究的新进展

本结合最后的典型量子物理实验,如用冷原子Bragg散射实现的“which-way”实验,量子退相干过程的微腔QED检验和C60分子的量子干涉等,比较系统地介绍了量子理论基本问题若干研究的新进展,特别强调了处于其核心的量子测量问题及其相关的基本概念和基本思想,如EPR佯谬和Bell不等式,量子退相干和量子纠缠,从理论和实验结合的角度本阐述了被测系统和测量仪器的相互作用怎样导致量子测量的一般动力学过程,由此还讨论了外部环境和内部运动怎样诱导量子退相干和量子耗散,对“薛定谔猫佯谬”和“宏观物体空间局域化描述”给出了可能的物理解释,最后,通过具体例子,本简单地讨论了量子物理基本问题的研究结果对量子信息的应用。     

On Convexity of Generalized Wigner–Yanase–Dyson Information

The convexity of the Wigner–Yanase–Dyson information, as first proved by Lieb, is a deep and fundamental result because it leads to the strong subadditivity of quantum entropy. The Wigner–Yanase–Dyson information is a particular kind of quantum Fisher information with important applications in quantum estimation theory. But unlike the quantum entropy, which is the unique natural quantum extension of the classical Shannon entropy, there are many different variants of quantum Fisher information, and it is desirable to investigate their convexity. This article is devoted to studying the convexity of a direct generalization of the Wigner–Yanase–Dyson information. Some sufficient conditions are obtained, and some necessary conditions are illustrated. In a particular case, a surprising necessary and sufficient condition is obtained. Our results reveal the intricacy and subtlety of the convexity issue for general quantum Fisher information.      

A Toss without a Coin: Information,Discontinuity, and Mathematics in Quantum Theory

The article argues that—at least in certain interpretations, such as the one assumed in this article under the heading of “reality without realism”—the quantum-theoretical situation appears as follows: While—in terms of probabilistic predictions—connected to and connecting the information obtained in quantum phenomena, the mathematics of quantum theory (QM or QFT), which is continuous, does not represent and is discontinuous with both the emergence of quantum phenomena and the physics of these phenomena, phenomena that are physically discontinuous with each other as well. These phenomena, and thus this information, are described by classical physics. All actually available information (in the mathematical sense of information theory) is classical: it is composed of units, such as bits, that are—or are contained in—entities described by classical physics. On the other hand, classical physics cannot predict this information when it is created, as manifested in measuring instruments, in quantum experiments, while quantum theory can. In this epistemological sense, this information is quantum. The article designates the discontinuity between quantum theory and the emergence of quantum phenomena the “Heisenberg discontinuity”, because it was introduced by W. Heisenberg along with QM, and the discontinuity between QM or QFT and the classical physics of quantum phenomena, the “Bohr discontinuity”, because it was introduced as part of Bohr’s interpretation of quantum phenomena and QM, under the assumption of Heisenberg discontinuity. Combining both discontinuities precludes QM or QFT from being connected to either physical reality, that ultimately responsible for quantum phenomena or that of these phenomena themselves, other than by means of probabilistic predictions concerning the information, classical in character, contained in quantum phenomena. The nature of quantum information is, in this view, defined by this situation. A major implication, discussed in the Conclusion, is the existence and arguably the necessity of two—classical and quantum—or with relativity, three and possibly more essentially different theories in fundamental physics.     

The role of causality in ensuring the ultimate security of relativistic quantum cryptography

One of the central points of quantum information theory is the problem of ultimate security of quantum cryptography; i.e., the security that is due only to the fundamental laws of nature rather than to technical restrictions. It is shown that a relativistic quantum cryptosystem proposed in this paper is ultimately secure against any eavesdropping attempts. The application of relativistic causality makes it possible to simply prove the security of the cryptosystem. Moreover, because the scheme does not involve collective measurements and quantum codes, it can be experimentally implemented even at the current level of optical fiber technologies.     

Nonquasinormal modes and black hole physics

The near-horizon geometry of a large class of extremal and near-extremal black holes in string and M-theory contains three-dimensional asymptotically anti-de Sitter space. Motivated by this structure, we are led naturally to a discrete set of complex frequencies defined in terms of the monodromy at the inner and outer horizons of the black hole. We show that the correspondence principle, whereby the real part of these "nonquasinormal frequencies" is identified with certain fundamental quanta, leads directly to the correct quantum behavior of the near-horizon Virasoro algebra, and thus the black hole entropy. Remarkably, for the rotating black hole in five dimensions we also reproduce the fractionization of conformal weights predicted in string theory.     

量子开系统理论及其应用

量子物理是当代科学发展的基石,多次引发高技术革命.它与信息科学结合,产生了交叉学科——量子信息,为突破计算机芯片的尺度极限提供了全新的解决思路.自1987年起,文章作者及其合作者对量子开系统理论、量子退相干及其相关的量子物理基本问题进行了系统的探索,契合了最近10年量子信息研究的快速发展.文章首先结合上世纪70年代末彭桓武先生关于量子开系统(阻尼谐振子的量子化)的重要研究工作,介绍了量子开系统的基本概念及其研究的科学意义,同时简略介绍了文章作者及其合作者在量子开系统理论及其在量子信息应用方面的系列研究工作.     

Asymptotic quantum cloning is state estimation

The impossibility of perfect cloning and state estimation are two fundamental results in quantum mechanics. It has been conjectured that quantum cloning becomes equivalent to state estimation in the asymptotic regime where the number of clones tends to infinity. We prove this conjecture using two known results of quantum information theory: the monogamy of quantum correlations and the properties of entanglement breaking channels.     

Correlations beyond the horizon

It is a fundamental feature of quantum field theory that correlations between observable quantities occur over all spacetime regions. In particular, in cosmological models with horizons, such correlations will be present in regions which lie outside of each other's horizon. Such correlations may play an important role in processes occurring in the early universe.This essay received the first award from the Gravity Research Foundation, 1992—Ed.     

Chern-Simons expectation values and quantum horizons from loop quantum gravity and the Duflo map

We report on a new approach to the calculation of Chern-Simons theory expectation values, using the mathematical underpinnings of loop quantum gravity, as well as the Duflo map, a quantization map for functions on Lie algebras. These new developments can be used in the quantum theory for certain types of black hole horizons, and they may offer new insights for loop quantum gravity, Chern-Simons theory and the theory of quantum groups.     

Wootters’ distance revisited: a new distinguishability criterium

The notion of distinguishability between quantum states has shown to be fundamental in the frame of quantum information theory. In this paper we present a new distinguishability criterium by using a information theoretic quantity: the Jensen-Shannon divergence (JSD). This quantity has several interesting properties, both from a conceptual and a formal point of view. Previous to define this distinguishability criterium, we review some of the most frequently used distances defined over quantum mechanics Hilbert space. In this point our main claim is that the JSD can be taken as a unifying distance between quantum states.