Quantum Mechanical Properties Research Articles

Quantum web of trust

AbstractAuthentication is the foremost requirement for any online secure transaction. In post quantum era, public key encryption is considered no longer a safe option. The research is therefore, progressing toward providing a quantum resistant solution using both classical as well as quantum computing medium. The paper proposes a quantum based mutual authentication protocol for autonomous system, utilizing the properties of quantum mechanics for exchange, storage and validation of confidential data. The protocol so designed evolves into a chain of mutually trusted nodes to form quantum web of trust. The protocol cater for devices infected with malware by utilizing physically unclonable function inside trusted platform module. The mathematical expressions conveying the correctness of operations has been demonstrated on a quantum machine to verify the efficacy of the protocol. The security analysis demonstrates the ability of the proposed protocol to mitigate cyber attacks and eavesdropping in the network.

Ground state of nonassociative hydrogen and upper bounds on the magnetic charge of elementary particles

Formulations of magnetic monopoles in a Hilbert-space formulation of quantum mechanics require Dirac's quantization condition of magnetic charge, which implies a large value that can easily be ruled out for elementary particles by standard atomic spectroscopy. However, an algebraic formulation of non-associative quantum mechanics is mathematically consistent with fractional magnetic charges of small values. Here, spectral properties in non-associative quantum mechanics are derived, applied to the ground state of hydrogen with a magnetically charged nucleus. The resulting energy leads to new strong upper bounds for the magnetic charge of various elementary particles that can appear as the nucleus of hydrogen-like atoms, such as the muon or the antiproton.

Electronic Coherence and Coherent Dephasing in the Optical Control of Electrons in Graphene.

Electronic coherence is of utmost importance for the access and control of quantum-mechanical solid-state properties. Using a purely electronic observable, the photocurrent, we measure a lower bound of the electronic coherence time of 22 ± 4 fs in graphene. The photocurrent is ideally suited to measure electronic coherence, as it is a direct result of coherent quantum-path interference, controlled by the delay between two ultrashort two-color laser pulses. The maximum delay for which interference between the population amplitude injected by the first pulse interferes with that generated by the second pulse determines the electronic coherence time. In particular, numerical simulations reveal that the experimental data yields a lower bound on the electronic coherence time, masked by coherent dephasing due to the broadband absorption in graphene. We expect that our results will significantly advance the understanding of coherent quantum control in solid-state systems ranging from excitation with weak fields to strongly driven systems.

A Multi-Image Cryptosystem Using Quantum Walks and Chebyshev Map

The ubiquity of image and video applications in our daily lives makes data security and privacy prominent concerns for everyone. Among others, various image cryptosystems are relied upon to provide the necessary safeguards. With the inevitable realisation of quantum computing hardware, however, the anticipated quantum supremacy entails effortless violation of the integrity of even the best cryptosystems. Quantum walks (QWs) utilise the potent properties of quantum mechanics to provide randomness via stochastic transitions between states. Our study exploits these properties of QWs to design a multi-image cryptosystem. Furthermore, we infuse the symmetricity and orthogonality of Chebyshev maps into the QWs to realise a powerful cryptosystem that guarantees data integrity, authentication, and anonymity of the resulting images. These properties are validated via extensive simulation-based experiments that produce average values of NPCR as 99.606%, UACI as 33.45%, global entropy as 7.9998, and chi-square test as 238.14. Therefore, the proposed cryptosystem provides ordnance to protect images from illicit tampering during the era.

Topological Chemograph Analysis Theory As a Promising Approach to the Simulation Modeling of the Quantum-Mechanical Properties of Molecules: Part I. On the Generation of Feature Descriptions of Molecules

Topological Chemograph Analysis Theory As a Promising Approach to the Simulation Modeling of the Quantum-Mechanical Properties of Molecules: Part I. On the Generation of Feature Descriptions of Molecules

Exchange-Bias Quantum Tunneling of the Magnetization in a Dysprosium Dimer.

Single-molecule magnets (SMMs) have been shown to possess bewildering phenomena leading to their proposal in several futuristic applications ranging from data storage devices to the basic unit of quantum computers. The main characteristic for the proposal of SMMs in such schemes is their inherent and intriguing quantum mechanical properties, which in turn, could be exploited in novel devices with larger capacities, such as for data storage or enhanced properties, such as quantum computers. In the quest of SMMs displaying such intriguing quantum effects, herein, we explore the synthesis, structural, and magnetic characterization of a dimeric dysprosium-based SMM composed of a tetradentate Schiff-base ligand with formula [Dy2(HL)2(benz)2(NO3)2]. Magnetic studies show that the complex is an SMM, while sub-Kelvin μ-SQUID studies revealed the exchange-bias characteristics of the system attributed to the presence of exchange interaction between the Dy3+ pair.

Soft decoding of short/medium length codes using ordered statistics for quantum key distribution

Quantum key distribution (QKD) is a cryptographic communication protocol that utilizes quantum mechanical properties for provable absolute security against an eavesdropper. The communication is carried between two terminals using random photon polarization states represented through quantum states. Both these terminals are interconnected through disjoint quantum and classical channels. Information reconciliation using delay controlled joint decoding is performed at the receiving terminal. Its performance is characterized using data and error rates. Achieving low error rates is particularly challenging for schemes based on error correcting codes with short code lengths. This article addresses the decoding process using ordered statistics decoding for information reconciliation of both short and medium length Bose–Chaudhuri–Hocquenghem codes over a QKD link. The link’s quantum channel is modeled as a binary symmetric quantum depolarization channel, whereas the classical channel is configured with additive white Gaussian noise. Our results demonstrate the achievement of low bit error rates, and reduced decoding complexity when compared to other capacity achieving codes of similar length and configuration.

Vibrational Spectral Studies, Quantum Mechanical Properties, and Biological Activity Prediction and Inclusion Molecular Self-Assembly Formation of N-N’-Dimethylethylene Urea

A cyclic urea analog, N-N'-dimethylethylene urea, was studied using different spectral methods like FT-IR, FT-Raman, and UV-VIS methods followed by computational simulations. The experimental and simulated spectra are compared, and a detailed assignment of vibrations and potential energy distribution is made. It was followed by various quantum mechanical studies like frontier orbital analysis, energy descriptors, average local ionization energies, and nonlinear optical properties. The NBO gave an insight into the various intramolecular stabilizing electron delocalization by hyperconjugation. Noncovalent interaction analysis provided various types of interactions present in the molecule. We also studied ALIE, local information entropy, electron localized function, reduced density gradient studies, localized orbital locator studies, and other analyses. Molecular docking results indicated that this urea derivative acted as an ATP-hydrolysing inhibitor, and the drug delivery ability of cyclodextrin on NND was tested by forming an inclusion complex with both compounds with dispersion and without dispersion interaction.

The Contribution of NMR Spectroscopy in Understanding Perovskite Stabilization Phenomena.

Although it has been exploited since the late 1900s to study hybrid perovskite materials, nuclear magnetic resonance (NMR) spectroscopy has only recently received extraordinary research attention in this field. This very powerful technique allows the study of the physico-chemical and structural properties of molecules by observing the quantum mechanical magnetic properties of an atomic nucleus, in solution as well as in solid state. Its versatility makes it a promising technique either for the atomic and molecular characterization of perovskite precursors in colloidal solution or for the study of the geometry and phase transitions of the obtained perovskite crystals, commonly used as a reference material compared with thin films prepared for applications in optoelectronic devices. This review will explore beyond the current focus on the stability of perovskites (3D in bulk and nanocrystals) investigated via NMR spectroscopy, in order to highlight the chemical flexibility of perovskites and the role of interactions for thermodynamic and moisture stabilization. The exceptional potential of the vast NMR tool set in perovskite structural characterization will be discussed, aimed at choosing the most stable material for optoelectronic applications. The concept of a double-sided characterization in solution and in solid state, in which the organic and inorganic structural components provide unique interactions with each other and with the external components (solvents, additives, etc.), for material solutions processed in thin films, denotes a significant contemporary target.

Asymptotically consistent measures of general quantum resources: Discord, non-Markovianity, and non-Gaussianity

Quantum resource theories provide a unified framework to quantitatively analyze inherent quantum properties as resources for quantum information processing. So as to investigate the best way for quantifying resources, desirable axioms for resource quantification have been extensively studied through axiomatic approaches. However, a conventional way of resource quantification by resource measures with such desired axioms may contradict rates of asymptotic transformation between resourceful quantum states due to an approximation in the transformation. In this paper, we establish an alternative axiom, asymptotic consistency of resource measures, and we investigate asymptotically consistent resource measures, which quantify resources without contradicting the rates of the asymptotic resource transformation. We prove that relative entropic measures are consistent with the rates for a broad class of resources, i.e., all convex finite-dimensional resources, e.g., entanglement, coherence, and magic, and even some nonconvex or infinite-dimensional resources such as quantum discord, non-Markovianity, and non-Gaussianity. These results show that consistent resource measures are widely applicable to the quantitative analysis of various inherent quantum-mechanical properties.

A quantum pseudo-random number generation scheme

Quantum random key distribution based on physical properties of quantum mechanics has high security and true randomness, but it has the disadvantages of low key generation efficiency and high cost. The classic pseudo-random number generator has the advantages of simple algorithm and high key generation efficiency, but it has extremely strict requirements on the security and randomness of the "seed". Based on the analysis of two unrelated technologies, this paper proposes a pseudo-random number generation scheme based on quantum key distribution. This scheme makes full use of quantum key distribution to share a short quantum random number-seed between the two communicating parties, then inputs the seed into a pseudo-random number generator. Finally, the two communicating parties share a long random number to encrypt the communication content. Research shows that compared with classic quantum key distribution and classic pseudo-random number generator, this scheme has stronger security, better randomness, and higher key generation efficiency.

A community-powered search of machine learning strategy space to find NMR property prediction models.

The rise of machine learning (ML) has created an explosion in the potential strategies for using data to make scientific predictions. For physical scientists wishing to apply ML strategies to a particular domain, it can be difficult to assess in advance what strategy to adopt within a vast space of possibilities. Here we outline the results of an online community-powered effort to swarm search the space of ML strategies and develop algorithms for predicting atomic-pairwise nuclear magnetic resonance (NMR) properties in molecules. Using an open-source dataset, we worked with Kaggle to design and host a 3-month competition which received 47,800 ML model predictions from 2,700 teams in 84 countries. Within 3 weeks, the Kaggle community produced models with comparable accuracy to our best previously published 'in-house' efforts. A meta-ensemble model constructed as a linear combination of the top predictions has a prediction accuracy which exceeds that of any individual model, 7-19x better than our previous state-of-the-art. The results highlight the potential of transformer architectures for predicting quantum mechanical (QM) molecular properties.

Solvent enhancement and isomeric effects on the NLO properties of a photoinduced cis-trans azomethine chromophore: A sequential MC/QM study

This work uses a sequential Monte Carlo/Quantum Mechanics procedure to discuss how specific solute-solvent interactions and the photoinduced cis-trans isomerization affect the nonlinear optical (NLO) response of a recently synthesized azo-azomethine dye. The results show that the trans geometry increases the number of solvent molecules around the solute concerning the cis structure. Consequently, the trans isomer performed the major number of hydrogen-bonded structures with the solvent molecules. Considering the solvent contribution to the quantum mechanical properties, the results show that the solute polarization affects drastically all electronic properties drastically. For instance, concerning the vacuum conditions, the molecular dipole moment increases ca. 25% insolvent. Moreover, from vacuum to solvent, Density Functional Theory methods coupled to 6-311++G(d,p) basis set to show that the first and second-hyperpolarizability (β and γ) increase ca. 12% for the trans structure, indicating a high-power generation of second and third harmonic, which can be 580 times greater than that reported for urea (β=0.34×10-30 esu), which is a common NLO chromophore. Finally, the photo-induced cis-trans isomerization tunes the NLO response of the material from βcis=53.31×10-30 esu to βtrans=197×10-30 esu, which means an improvement of 270%.

QHSL: A quantum hue, saturation, and lightness color model

Image processing with any potential quantum computing hardware requires a quantum color model capable of capturing and manipulating color information in images. In this study, a quantum hue, saturation, and lightness (QHSL) model is proposed as a first attempt to encode perceptually relevant triplet color components using the properties of quantum mechanics (i.e., entanglement and parallelism). The proposed color model was used to define a representation of two-dimensional QHSL images for storage and transformation with fewer computing resources. The configuration of color-assignment attributes within this QHSL representation offer useful applications for image analysis. Specifically, a pseudocolor technique with flexible gray depth divisions is presented for highlighting fine visual details.

Endless skies and open seas – how birds and fish navigate

Abstract Every year, billions of animals leave their home range and start seasonal migrations in order to find more favorable resources and to escape harsh environmental conditions. These round trips often span thousands of kilometers. To successfully navigate along their route, animals rely on various external references. While landmarks and celestial cues like stars or the sun are easy to imagine as guidance on these journeys, using the geomagnetic field for orientation is more elusive. The geomagnetic field is an omnipresent cue, which can be sensed and relied upon by many animals, even when visual cues are sparse. How magnetic fields can be perceived seems to vary between birds and fish. While birds seem to use a mechanism based on the quantum mechanical properties of electron spins, fish may have evolved a compass similar in its function to the technical devises developed by humans. How these mechanisms work precisely and how they are integrated are research questions addressed in SFB 1372.

Hierarchy of quantum operations in manipulating coherence and entanglement

Quantum resource theory under different classes of quantum operations advances multiperspective understandings of inherent quantum-mechanical properties, such as quantum coherence and quantum entanglement. We establish hierarchies of different operations for manipulating coherence and entanglement in distributed settings, where at least one of the two spatially separated parties are restricted from generating coherence. In these settings, we introduce new classes of operations and also characterize those maximal, i.e., the resource-non-generating operations, progressing beyond existing studies on incoherent versions of local operations and classical communication and those of separable operations. The maximal operations admit a semidefinite-programming formulation useful for numerical algorithms, whereas the existing operations not. To establish the hierarchies, we prove a sequence of inclusion relations among the operations by clarifying tasks where separation of the operations appears. We also demonstrate an asymptotically non-surviving separation of the operations in the hierarchy in terms of performance of the task of assisted coherence distillation, where a separation in a one-shot scenario vanishes in the asymptotic limit. Our results serve as fundamental analytical and numerical tools to investigate interplay between coherence and entanglement under different operations in the resource theory.

Entanglement clustering for ground-stateable quantum many-body states

Despite their fundamental importance in dictating the quantum mechanical properties of a system, ground states of many-body local quantum Hamiltonians form a set of measure zero in the many-body Hilbert space. Hence determining whether a given many-body quantum state is ground-stateable is a challenging task. Here we propose an unsupervised machine learning approach, dubbed the Entanglement Clustering ("EntanCl"), to separate out ground-stateable wave functions from those that must be excited state wave functions using entanglement structure information. EntanCl uses snapshots of an ensemble of swap operators as input and projects this high dimensional data to two-dimensions, preserving important topological features of the data associated with distinct entanglement structure using the uniform manifold approximation and projection (UMAP). The projected data is then clustered using K-means clustering with $k=2$. By applying EntanCl to two examples, a one-dimensional band insulator and the two-dimensional toric code, we demonstrate that EntanCl can successfully separate ground states from excited states with high computational efficiency. Being independent of a Hamiltonian and associated energy estimates, EntanCl offers a new paradigm for addressing quantum many-body wave functions in a computationally efficient manner.

CrystalExplorer: a program for Hirshfeld surface analysis, visualization and quantitative analysis of molecular crystals.

CrystalExplorer is a native cross-platform program supported on Windows, MacOS and Linux with the primary function of visualization and investigation of molecular crystal structures, especially through the decorated Hirshfeld surface and its corresponding two-dimensional fingerprint, and through the visualization of void spaces in the crystal via isosurfaces of the promolecule electron density. Over the past decade, significant changes and enhancements have been incorporated into the program, such as the capacity to accurately and quickly calculate and visualize quantitative intermolecular interactions and, perhaps most importantly, the ability to interface with the Gaussian and NWChem programs to calculate quantum-mechanical properties of molecules. The current version, CrystalExplorer21, incorporates these and other changes, and the software can be downloaded and used free of charge for academic research.

Vibrational, electronic and reactivity insight on (5-chloro-benzofuran-3-yl)-acetic acid hydrazide: A Spectroscopic and DFT approach

Extensive quantum chemical calculation have been carried out to examine the Fourier Transform Infrared(FT-IR), Fourier Transform Raman(FT-Raman) and Nuclear magnetic resonance(NMR) spectra of (5-chloro-benzofuran-3-yl)-acetic acid hydrazide (5CBAH) molecule. The Gaussian computations have been carried out by DFT method using B3LYP/6-311++G (d, p) basis sets. The fundamental vibrational frequencies and intensities of the vibrational bands are analysed with the help of optimized structure. The theoretical NMR chemical shift values have been obtained using gauge independent atomic orbital (GIAO) method. The computed band gap energy of HOMO and LUMO depicts that charge transfer existed within the molecule. The internal molecular electronic interactions and their stabilizing energies are identified by the NBO analysis. The MEP map analysis is conducted to determine the chemical reactive site of the molecule. The thermodynamic properties of the title compound are studied for different temperatures. Non-linear optical properties and Fukui activity are also performed. The electron distribution and reactive site on the surface of the molecule are analyzed using ELF and LOL analysis. Atoms in Molecule (AIM) analysis is used to study the nature of interactions in molecular structure and to categorize and recognize the bonding interactions on the basis of quantum mechanical properties. The noncovalent interaction (NCI) analysis provides the most important interaction information's such as van der Waals interactions, hydrogen bonds and steric interactions present in the molecule.

Definitions and Security of Quantum Electronic Voting

Recent advances indicate that quantum computers will soon be reality. Motivated by this ever more realistic threat for existing classical cryptographic protocols, researchers have developed several schemes to resist “quantum attacks.” In particular, for electronic voting (e-voting), several schemes relying on properties of quantum mechanics have been proposed. However, each of these proposals comes with a different and often not well-articulated corruption model, has different objectives, and is accompanied by security claims that are never formalized and are at best justified only against specific attacks. To address this, we propose the first formal security definitions for quantum e-voting protocols. With these at hand, we systematize and evaluate the security of previously proposed quantum e-voting protocols; we examine the claims of these works concerning privacy, correctness, and verifiability, and if they are correctly attributed to the proposed protocols. In all non-trivial cases, we identify specific quantum attacks that violate these properties. We argue that the cause of these failures lies in the absence of formal security models and references to the existing cryptographic literature.