Scholar iON
Academic Synthesis
The collection of papers within the "quant-ph" category highlights diverse approaches to quantum mechanics, with a focus on improving theoretical frameworks and addressing specific protocols. The withdrawn paper by Anthony Sudbery, superseded by Makhlin's work, and the replacement of K. A. Kirkpatrick's paper, underscore the evolving nature of research in quantum information and the importance of refining theoretical models. Zhanjun Zhang's commentary on the ping-pong communication protocol indicates active discourse on the security and robustness of quantum communication methods, reflecting ongoing efforts to address vulnerabilities in quantum protocols. Additionally, Jian Tang and An Min Wang's exploration of improved perturbation theory for transition probability in quantum systems underscores a trend towards enhancing calculation precision and efficiency, suggesting a consensus on the need for robust computational tools to tackle complex quantum systems. Overall, these works collectively signify a dynamic field striving towards more precise, efficient, and secure quantum mechanical frameworks.
This paper is withdrawn by the author. It is superseded by Makhlin's paper quant-ph/0002045.
This is a comment on PRL90(03)157901 by Antoni Wojcik (quant-ph/0211199)
Withdrawn. Replaced by quant-ph/0308160 (cf accompanying txt file)
As is well known, the existed perturbation theory can be applied to calculations of energy, state and transition probability in many quantum systems. However, there are different paths and methods to improve its calculation precision and efficiency in our view. According to an improved scheme of perturbation theory proposed by [An Min Wang, quant-ph/0611217], we reconsider the transition probability and perturbed energy for a Hydrogen atom in a constant magnetic field. We find the results obtained by using Wang's scheme are indeed more satisfying in the calculation precision and efficiency. Therefore, Wang's scheme can be thought of as a powerful tool in the perturbation calculation of quantum systems.
Recently a great deal of attention has focused on quantum computation following a sequence of results suggesting that quantum computers are more powerful than classical probabilistic computers. Following Shor's result that factoring and the extraction of discrete logarithms are both solvable in quantum polynomial time, it is natural to ask whether all of NP can be efficiently solved in quantum polynomial time. In this paper, we address this question by proving that relative to an oracle chosen uniformly at random, with probability 1, the class NP cannot be solved on a quantum Turing machine in time $o(2^{n/2})$. We also show that relative to a permutation oracle chosen uniformly at random, with probability 1, the class $NP \cap coNP$ cannot be solved on a quantum Turing machine in time $o(2^{n/3})$. The former bound is tight since recent work of Grover shows how to accept the class NP relative to any oracle on a quantum computer in time $O(2^{n/2})$.
In this paper we treat a cavity QED quantum computation. Namely, we consider a model of quantum computation based on n atoms of laser-cooled and trapped linearly in a cavity and realize it as the n atoms Tavis-Cummings Hamiltonian interacting with n external (laser) fields.
We solve the Schr{\" o}dinger equation of the model in the weak coupling regime to construct the controlled NOT gate in the case of n=2, and to construct the controlled-controlled NOT gate in the case of n=3 by making use of several resonance conditions and rotating wave approximation associated to them. We also present an idea to construct general quantum circuits.
The approach is more sophisticated than that of the paper [K. Fujii, Higashida, Kato and Wada, Cavity QED and Quantum Computation in the Weak Coupling Regime, J. Opt. B : Quantum Semiclass. Opt. {\bf 6} (2004), 502].
Our method is not heuristic but completely mathematical, and the significant feature is based on a consistent use of Rabi oscillations.
From its inception at the beginning of the eighties, with milestone results and ideas such as quantum simulation, the no-cloning theorem, and quantum computers, quantum information has established itself over the next decades, being nowadays a fast-developing field at the interface between fundamental science and a variety of promising technologies. In this work we aim to offer a portrait of this dynamic field, analyzing the statistical properties of the network of collaborations among its researchers. Using the quant-ph section from the arXiv as our database, we draw several conclusions on its properties. In particular, we show that the quantum information network of collaborations displays the small-world property, is very aggregated and assortative, being also in line with Newman's findings as for the presence of hubs and the Lotka's law regarding the average number of publications per author.
Researchers working in lattice field theory constitute an established community since the early 1990s, and around the same time the online open-access e-print repository arXiv was created. The fact that this field has a specific arXiv section, hep-lat, which is comprehensively used, provides a unique opportunity for a statistical study of its evolution over the last three decades. We present data for the number of entries, $E$, published papers, $P$, and citations, $C$, in total and separated by nations. We compare them to six other arXiv sections (hep-ph, hep-th, gr-qc, nucl-th, quant-ph, cond-mat) and to two socio-economic indices of the nations involved: the Gross Domestic Product (GDP) and the Education Index (EI). We present rankings, which are based either on the Hirsch Index H, or on the linear combination $Ξ£= E + P + 0.05 C$. We consider both extensive and intensive national statistics, i.e. absolute and relative to the population or to the GDP.
Although it has been almost 100 years since the beginnings of quantum mechanics, the discussions about its interpretation still do not cease. Therefore, a survey of opinions regarding this matter is of particular interest. This poll was conducted following an idea and using the methodology of Schlosshauer et al. (arXiv:1301.1069 [quant-ph]), but among a slightly different group. It is supposed to give another snapshot of attitudes towards the interpretation of quantum mechanics and keep discourse about this topic alive.
We propose that quantum entanglement is a special sort of selection artefact, explicable as a combination of (i) collider bias and (ii) a boundary constraint on the collider variable. We show that the proposal is valid for a special class of (`W-shaped') Bell experiments involving delayed-choice entanglement swapping, and argue that it can be extended to the ordinary (`V-shaped') case. The proposal requires no direct causal influence outside lightcones, and may hence offer a way to reconcile Bell nonlocality and relativity. The main argument is a detailed version of an approach previously outlined in arXiv:2404.13928 [quant-ph].