Applications In Quantum Physics Research Articles

Photoelectric effect on concrete artifacts produced with the addition of luminescent substances and polymer residues

Among the practical applications of Quantum Physics, photoluminescence has stood out in different contexts in Engineering and Architecture. Due to the photoelectric effect, certain substances emit photons after being exposed to solar energy. In research in Mexico and Europe, these substances were applied to obtain a photoluminescent effect on bicycle paths. The objective of the research is to investigate the behavior of polymeric residues with the luminescent effect of rare-earth materials in the production of concrete artifacts to illuminate pedestrian and cyclist paths. The concrete blocks were produced with the addition of polymeric recycling waste and luminescent materials, exposed to solar radiation, and tested for mechanical strength. The results of the experiments showed that the polymer residue in concrete significantly increases photon emission, especially when it is processed by extrusion. Although the mixture of photoluminescent materials and polymers reduces the strength of concrete, it still met research objectives for a product meant to illuminate pedestrian and cyclist paths.

Detecting an Itinerant Optical Photon Twice without Destroying It.

Nondestructive quantum measurements are central for quantum physics applications ranging from quantum sensing to quantum computing and quantum communication. Employing the toolbox of cavity quantum electrodynamics, we here concatenate two identical nondestructive photon detectors to repeatedly detect and track a single photon propagating through a 60m long optical fiber. By demonstrating that the combined signal-to-noise ratio of the two detectors surpasses each single one by about 2 orders of magnitude, we experimentally verify a key practical benefit of cascaded nondemolition detectors compared to conventional absorbing devices.

О КВАНТОВОМ КОМПЬЮТЕРЕ И КВАНТОВОЙ МЕДИЦИНЕ

The foundations of quantum physics have been laid by Max Planck, who suggested that energy couldn’t be absorbed and radiated continuously, but only in separate portions - these portions were called quanta. His ideas were confirmed in numerous physical experiments on the photo effect, the structure of the atom and atomic nucleus, brilliantly performed by Bohr and Rutherford. All this in the aggregate made it possible to eliminate the border between matter and waves, predicted by Louis de Broil. In this way the foundations of quantum mechanics were laid = Heisenberg and Schrödinger did this work. Many manifestations of quantum physics can already be observed in everyday life. These are optical quantum generators, computer CDs, and integrated circuits and lots and lots of this. In recent years, the researchers have drawn their attention to other quantum physics applications related to queries. By their design, this work will be carried out in the future by quantum computers. The article presents a short report on the quantum computer and the prospects for its use in quantum medicine.

Properties of Pancharatnam Phase and Entanglement of a Five-Level Atom Interacting with a Squeezed Field

We introduce a quantum scheme where a single five-level atom interacts with a single-mode cavity field by a time-dependent coupling. During the interaction, the temporal behavior of the quantum entropy in the atomic basis is compared with that of the Mandel parameter used to quantify the nonclassical properties of the field. With the field prepared in a squeezed coherent state, the atomic quantum entropy is then used to quantify the entanglement or the nonlocal correlation of the five-level atom (5 LA) – field system. The influence of one- and two-photon transitions and the atomic motion on the degree of entanglement and the Pancharatnam phase is analyzed. The analysis emphasizes that both the time dependence and photon multiplicity play an important role in the evolution of the degree of entanglement, the Pancharatnam phase, and nonclassical properties. This insight may be very useful in various applications in quantum physics and quantum optics.

Dirac and normal states on Weyl\u2013von Neumann algebras

We study particular classes of states on the Weyl algebra mathcal {W} associated with a symplectic vector space S and on the von Neumann algebras generated in representations of mathcal {W}. Applications in quantum physics require an implementation of constraint equations, e.g., due to gauge conditions, and can be based on the so-called Dirac states. The states can be characterized by nonlinear functions on S, and it turns out that those corresponding to non-trivial Dirac states are typically discontinuous. We discuss general aspects of this interplay between functions on S and states, but also develop an analysis for a particular example class of non-trivial Dirac states. In the last part, we focus on the specific situation with S = L^2(mathbb {R}^n) or test functions on mathbb {R}^n and relate properties of states on mathcal {W} with those of generalized functions on mathbb {R}^n or with harmonic analysis aspects of corresponding Borel measures on Schwartz functions and on temperate distributions.

Investigation of Random Matrix Theory for Statistical Mechanics and Quantum Physics Applications

Due to its capability to explain large systems with chaotic behaviour, Random Matrix Theory (RMT) has drawn a lot of interest in the domains of Statistical Mechanics and Quantum Physics. Investigating RMT's uses in these fields is the main goal of this study.RMT offers a potent framework for studying the behaviour of sizable ensembles of interacting particles in statistical mechanics. RMT enables the examination of different physical features including energy spectra and correlation functions by using random matrices as models for Hamiltonians. Advancements in disciplines like condensed matter physics and nuclear physics have been made possible by the universality aspects of RMT, which allow for the comprehension of universal features seen in many-body systems.RMT is an essential tool for understanding the statistical behaviour of quantum systems in quantum physics, especially when there are strong interactions present. It gives scientists a useful tool for describing the energy states and wave functions of complicated quantum systems, including those with chaotic dynamics. Understanding of phenomena including quantum transport, quantum entanglement, and quantum chaos has benefited by the knowledge obtained from RMT.With this study, we hope to add to the body of knowledge on RMT's uses in quantum physics and statistical mechanics. It offers important insights into the behaviour of complex systems and paves the road for improvements in these domains by investigating the characteristics of random matrices and their relationships to physical systems.

Scheme for automatic differentiation of complex loss functions with applications in quantum physics.

The past few years have seen a significant transfer of tools from machine learning to solve quantum physics problems. Automatic differentiation is one standard algorithm used to efficiently compute gradients of loss functions for generic neural networks. In this work we show how to extend automatic differentiation to the case of complex loss function in a way that can be readily implemented in existing frameworks and which is compatible with the common case of real loss functions. We then combine this tool with matrix product states and apply it to compute the ground state and the steady state of a close and an open quantum system. Compared to the traditional density matrix renormalization group algorithm, complex automatic differentiation allows both straightforward GPU accelerations as well as generalizations to different types of tensor and neural networks.

The Uniqueness of Stationary Solution for Nonlinear Random Reaction-diffusion Equation

We study a nonlinear random reaction-diffusion problem in abstract Banach spaces, driven by a real noise, with random diffusion coefficient and random initial condition. We consider a polynomial non linear term. The reaction-diffusion equation belongs to the class of parabolic stochastic partial differential equations. We assume that the initial condition is an element of Hilbert space. The real noise is a Wiener process. We construct a suitable stochastic basis and define the solution of reaction-diffusion problem in the weak sense. We define the stationary process in abstract Banach spaces in the strong sense of Doob-Rozanov. That is, the probability density function of the stochastic process is independent of time shift. We define the invariant measure for random reaction-diffusion equation in the sense of Arnold, DaPrato, and Zabczyk [1,2]. In other words, we define the invariant measure for random dynamical system, associated with random reaction-diffusion problem.
 Using the Variation Inequalities Theory, we prove the uniqueness of stationary solution for nonlinear random reaction-diffusion problem. The obtained theoretical results have several applications in Quantum Physics, Biology, Medicine, and Economic Sciences. Especially, we can study the existence of stationary solution for the stochastic models of tumor growth.

Approach to Financial Decision Making within Quantum Physics and Neurosciences

This paper focuses on the study of the functional relationships between the tools of neuroscience, neurofinance and psychology on the one hand, and quantum physics / quantum mechanics and neurophysiology on the other. Can physics / quantum mechanics help explain / understand human behavior through the Shrödinger cat platform (perhaps we can explain the most mysterious phenomena: human behavior - cerebral secretion?)? The concepts of quantum mechanics allow a good prediction of human decision making within Schrödinger's cat (two particles can talk to each other even at a distance of a galaxy, perhaps in this sense can help explain an extremely complex decision making system), and define the "connection of quantum models with neurophysiological processes in the brain “... which is a very complex problem.” (Haven and Khrennikov) The application of quantum physics and neuroscience in finance allows us to consider the complexity of financial decision making, while the connection between quantum physics and psychology manifests itself as the field of quantum physics seeks to understand the fundamental nature of particles. while the field of psychology seeks to explain human nature along with its inherent misconceptions.If decision-making is a process of gathering evidence in favor of different alternatives over time, the process is discontinued once the decision limit is reached, followed by choice of decision. e activity within the posterior parietal cortex several important questions remain unanswered. Neural mechanisms that support the accumulation of evidence record the activities of individual neurons in different parts of the prefrontal cortex (PFC) and the lateral intraparietal area (LIP).

Automatic differentiation of dominant eigensolver and its applications in quantum physics

We investigate the automatic differentiation of dominant eigensolver where only a small proportion of eigenvalues and corresponding eigenvectors are obtained. Backpropagation through the dominant eigensolver involves solving certain low-rank linear systems without direct access to the full spectrum of the problem. Furthermore, the backward pass can be conveniently differentiated again, which implies that in principle one can obtain arbitrarily higher order derivatives of the dominant eigen-decomposition process. These results allow for the construction of an efficient dominant eigensolver primitive, which has wide applications in quantum physics. As a demonstration, we compute second order derivative of the ground state energy and fidelity susceptibility of 1D transverse field Ising model through the exact diagonalization approach. We also calculate the ground state energy of the same model in the thermodynamic limit by performing gradient-based optimization of uniform matrix product states. By programming these computation tasks in a fully differentiable way, one can efficiently handle the dominant eigen-decomposition of very large matrices while still sharing various advantages of differentiable programming paradigm, notably the generic nature of the implementation and free of tedious human efforts of deriving gradients analytically.

Predicting research trends with semantic and neural networks with an application in quantum physics

The vast and growing number of publications in all disciplines of science cannot be comprehended by a single human researcher. As a consequence, researchers have to specialize in narrow subdisciplines, which makes it challenging to uncover scientific connections beyond the own field of research. Thus, access to structured knowledge from a large corpus of publications could help push the frontiers of science. Here, we demonstrate a method to build a semantic network from published scientific literature, which we call SemNet We use SemNet to predict future trends in research and to inspire personalized and surprising seeds of ideas in science. We apply it in the discipline of quantum physics, which has seen an unprecedented growth of activity in recent years. In SemNet, scientific knowledge is represented as an evolving network using the content of 750,000 scientific papers published since 1919. The nodes of the network correspond to physical concepts, and links between two nodes are drawn when two concepts are concurrently studied in research articles. We identify influential and prize-winning research topics from the past inside SemNet, thus confirming that it stores useful semantic knowledge. We train a neural network using states of SemNet of the past to predict future developments in quantum physics and confirm high-quality predictions using historic data. Using network theoretical tools, we can suggest personalized, out-of-the-box ideas by identifying pairs of concepts, which have unique and extremal semantic network properties. Finally, we consider possible future developments and implications of our findings.

Emission Spectrum and Nonclassical Properties of an Atom–Field System Under an Intensity-Dependent Field

In this paper, we investigate the emission spectrum of a two-level atomic system interacting with an optical radiation field based on photon-added coherent states of a pseudo-harmonic oscillator (PACSPHO). Also, the purity of the optical field initially prepared in the PACS-PHO is studied through the evolution of the field entropy. We examine the influence of the intensity-dependent field and the photon-transition number on the dynamic behavior of the emission spectrum and field purity. We explore the link between the field purity and the emission spectrum during the time evolution. Finally, we show how the emission spectrum is affected and changed according to the main physical parameters. We find that there is some kind of correlation between the emission spectrum and the field purity, which will be useful in different applications of quantum physics and spectroscopy.

Cicularly discretized coherent state representation and its application in quantum physics

Choosing a proper representation is the first step of numerically describing wave functions or solving Schrödinger equations. One of the widely used representations is discretized coherent state representation (DCSR). However, the DCSR performs badly in computation because of its overcompleteness (non-orthogonality) and high dimension in the phase space. We present a circularly discretized coherent state representation (CDCSR) and two corresponding fast algorithms to overcome the disadvantages of the DCSR. By using the CDCSR, the function can be simply expressed as same as that in an orthogonal representation. Using two fast algorithms, we can largely simplify the computational complexity.

Identifying quantum phase transitions using artificial neural networks on experimental data

Machine learning techniques such as artificial neural networks are currently revolutionizing many technological areas and have also proven successful in quantum physics applications. Here we employ an artificial neural network and deep learning techniques to identify quantum phase transitions from single-shot experimental momentum-space density images of ultracold quantum gases and obtain results, which were not feasible with conventional methods. We map out the complete two-dimensional topological phase diagram of the Haldane model and provide an accurate characterization of the superfluid-to-Mott-insulator transition in an inhomogeneous Bose-Hubbard system. Our work points the way to unravel complex phase diagrams of general experimental systems, where the Hamiltonian and the order parameters might not be known.

Breaking the quantum adiabatic speed limit by jumping along geodesics.

Quantum adiabatic evolutions find a broad range of applications in quantum physics and quantum technologies. The traditional form of the quantum adiabatic theorem limits the speed of adiabatic evolution by the minimum energy gaps of the system Hamiltonian. Here, we experimentally show using a nitrogen-vacancy center in diamond that, even in the presence of vanishing energy gaps, quantum adiabatic evolution is possible. This verifies a recently derived necessary and sufficient quantum adiabatic theorem and offers paths to overcome the conventionally assumed constraints on adiabatic methods. By fast modulation of dynamic phases, we demonstrate near-unit-fidelity quantum adiabatic processes in finite times. These results challenge traditional views and provide deeper understanding on quantum adiabatic processes, as well as promising strategies for the control of quantum systems.

Quantum State Conversion in Two-Level System Without Rotating-Wave Approximation via Non-Hermitian Shortcuts to Adiabaticity

Adiabatic theorem has found many important applications in quantum physics. Shortcuts to adiabaticity can effectively accelerate adiabatic process. We consider a two-level system (TLS) without rotating-wave approximation (RWA). Here, we propose a scheme to implement quantum state completely transfer. In our scheme, by adding unbalanced imaginary terms, now the Hamiltonian of the system is non-Hermitian form, we can nullify the nonadiabatic coupling and achieve fast quantum state conversion with high fidelity. The perfect population transfer can be achieved within a short time.

Interference, spectral momentum correlations, entanglement, and Bell inequality for a trapped interacting ultracold atomic dimer: Analogies with biphoton interferometry

Elucidating similarities and differences between quantum-optics biphoton interference phenomena and the quantum physics of quasi-one-dimensional double-well optically-trapped ultracold neutral bosonic or fermionic atoms, we show that the analog of the optical biphoton joint-coincidence spectral correlations, studied with massless non-interacting biphotons emanating from EPR-Bell-Bohm single-occupancy sources, corresponds to a distinct contribution in the total second-order momentum correlations of the massive, interacting, and time-evolving ultracold atoms. This single-occupancy contribution can be extracted from the total second-order momentum correlation function measured in time-of-flight experiments, which for the trapped atomic system contains, in general, a double-occupancy, NOON, component. The dynamics of the two-particle system are modeled by a Hubbard Hamiltonian. This partial coincidence spectrum is a cosine-square quantum beating dependent on the difference of the momenta of the two particles, while the corresponding coincidence probability proper, familiar from its role in describing the Hong-Ou-Mandel coincidence dip of overlapping photons, results from an integration over the particle momenta. Because the second-order momentum correlations are mirrored in the time-of-flight spectra in space, our theoretical findings provide impetus for time-of-flight experimental protocols for emulating with (massive) ultracold atoms venerable optical interferometries that use two space-time separated and entangled (massless) photons or double-slit optical sources. The implementation of such developments will facilitate testing of fundamental aspects and enable applications of quantum physics with trapped massive ultracold atoms, that is, investigations of nonlocality and violation of Bell inequalities, entanglement, and quantum information science.

Multiparameter QKD authentication protocol design over optical quantum channel

Quantum cryptography is the first application of quantum physics at the single photon level. The most important application of quantum cryptography is Quantum Key Distribution (QKD). One of the biggest problems of QKD implementation is enormous number of possible attacks, which puts out specific need for more refined simulation strategies in bridging the gap between theoretic models and their implementation. In this work we have introduced generalized optical architecture which can provide various solutions of some actual problems for two mostly used QKD protocols: BB84 and B92 protocols. Simulations, which included the influence of optical losses over a quantum channel with concrete realistic lengths, have confirmed validity and high level of provable security of the proposed generalized QKD authentication architecture. Due to simplicity of the proposed architecture and obtained QKD B92 protocol communication efficiency, we believe that it can be implemented, solving out some of the most relevant implementation problems which are common for both QKD protocols.

Controllable nonlinearity in a dual-coupling optomechanical system under a weak-coupling regime

Strong quantum nonlinearity gives rise to many interesting quantum effects and has wide applications in quantum physics. Herewe investigate the quantum nonlinear effect of an optomechanical system (OMS) consisting of both linear and quadratic coupling. Interestingly, a controllable optomechanical nonlinearity is obtained by applying a driving laser into the cavity. This controllable optomechanical nonlinearity can be enhanced into a strong coupling regime, even if the system is initially in the weak-coupling regime. Moreover, the system dissipation can be suppressed effectively, which allows the appearance of phonon sideband and photon blockade effects in the weak-coupling regime. This work may inspire the exploration of a dual-coupling optomechanical system as well as its applications in modern quantum science.

Levitons for electron quantum optics

AbstractSingle‐electron sources enable electron quantum optics experiments where single electrons emitted in a ballistic electronic interferometer play the role of a single photon emitted in an optical medium in quantum optics. A qualitative step has been made with the recent generation of single‐charge levitons obtained by applying Lorentzian voltage pulses on the contact of the quantum conductor. Simple to realize and operate, the source emits electrons in the form of striking minimal excitation states called levitons. We review the striking properties of levitons and their possible applications in quantum physics to electron interferometry and entanglement.Schematic generation of time‐resolved single charges called levitons using Lorentzian voltage pulses applied on a contact. A quantum point contact is used to partition the levitons for further analysis. Injecting levitons on opposite contacts with a delay enables us to probe electronic like Hong–Ou–Mandel correlations.