Abstract: Accurate generation and measurement of entangled states, such as the Bell state |Φ⁺⟩, are crucial benchmarks for assessing the capabilities and variability of Noisy Intermediate-Scale Quantum (NISQ) hardware. This work benchmarks the fidelity of preparing the |Φ⁺⟩ = (|00⟩ + |11⟩)/√2 state on different qubit pairs ([2, 3] and [7, 8]) of the ibm_kyiv quantum processor over multiple runs (N=5) and employs the deviation from perfect correlation as a quantitative analogy for the probability of unexpected decoupling in systems expected to exhibit strong correlation, such as linked economic indicators. Implementing the standard Hadamard and CNOT gate sequence for 4096 shots per run using the qiskit-ibm-runtime SamplerV2 primitive, we characterized the state preparation and measurement fidelity and applied mthree-based readout error mitigation. Experimental raw results revealed significant variability between layouts, yielding mean anti-correlated outcome probabilities P(Anti) = P(01) + P(10) of approximately 1.6% (±0.3%) for layout [2, 3] and 9.2% (±0.8%) for layout [7, 8]. This performance difference strongly correlated with reported hardware calibration metrics, particularly average readout error rates. Readout error mitigation successfully reduced P(Anti) to near-zero values (≤0.1%) for both layouts, achieving corrected correlated outcome probabilities P(Corr) = P(00) + P(11) of ~99.9-100.0%. Within our conceptual framework, the range of raw P(Anti) serves as a quantitative analogue for the likelihood of 'unexpected decoupling' under different inherent noise conditions, while the mitigated results suggest the potential to isolate underlying system dynamics from measurement noise. This research provides concrete multi-run fidelity benchmarks for ibm_kyiv, demonstrates the effectiveness of error mitigation, highlights performance variability linked to calibration data, and quantifies a range for the proposed economic uncertainty analogy.

Abstract: We present a reformulation of fundamental physics, transitioning from an enumeration of independent axioms to the solution of a single optimization problem derived from the structure of experiments. Any experiment comprises an initial preparation, a physical evolution, and a final measurement. Grounded in this structure, we determine the final measurement distribution by minimizing its entropy relative to its initial preparation distribution, subject to a natural constraint. Solving this optimization problem identifies a unified theory encompassing quantum mechanics, general relativity (acting on spacetime geometry), and Yang-Mills gauge theories (acting on internal spaces). Notably, consistency requirements restrict valid solutions to 3+1 dimensions, thus deriving spacetime dimensionality. This reformulation suggests that the established laws of physics, including their specific forces, symmetries, and dimensionality, emerge naturally from the requirement of the minimal informational change from preparation to measurement, consistent with the natural constraint.

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Despite their Nobel Prize-winning empirical implementation, the Bell inequality interpretation remains controversial. An objective analysis of Bell's work on nonlocality shows that Bell's rationale calls for reconsidering a widespread argument on quantum nonlocality, yielding a precise formulation free from the usual obscurities that lead to misleading controversies. By dismissing unnecessary metaphysical tenets, it is possible to probe the core of the problem and determine under what rational assumptions locality or nonlocality become feasible alternatives clarifying their relation to the Bell inequality. The approach renders a more balanced perspective over a long-standing polarized interpretative debate.

Abstract: This work presents a comprehensive study of atom–…eld interactions by examining how subtle variations in key parameters a⁄ect quantum dynamics. In our investigation, the time-dependent Stark shift (SS) is systematically varied from low (approximately 0:3) to high (around 3) values. Under weak Stark modulation, the system closely mirrors the traditional Jaynes–Cummings model, displaying smooth Rabi oscillations and modest ‡uctuations in quantum measures such as the Quantum Fisher Information (QFI), Von Neumann Entropy (VNE), and Negativity (Neg). As the Stark parameter increases, the atom and …eld are driven in and out of resonance more abruptly, leading to rapid, high-amplitude bursts of quantum entanglement (QE) and marked shifts in the Geometric Phase. The study further explores the role of a small nonzero initial phase (  = =4), which subtly alters the interference between the atom and …eld. This additional phase results in slight shifts in the timing and magnitude of QE peaks when compared with a purely real initial state. Additionally, the incorporation of detuning and atomic motion introduces o⁄-resonant e⁄ects and vibrational sidebands, respectively. These elements further complicate the energy exchange process and enrich the overall dynamics. Overall, the results underscore that even slight modi…cations in external parameters can lead to signi…cant variations in QE behavior and phase evolution, o⁄ering valuable insights for the …ne-tuning of quantum systems in advanced technological application.

Abstract: In connection with the International Year of Quantum Science and Technology, a review of joint works of the Lebedev Institute and different Mexican research groups is presented; specially related to solving the old problem of the state description not only by wave functions but also by conventional probability distributions analogous to quasiprobability distributions like the Wigner function. Also, explicit expressions of tomographic representations describing the quantum states of particles moving in known potential wells are obtained and briefly discussed. In particular, we present the examples of the tomographic distributions for the free evolution, finite and infinite potential wells, and the Morse potential. Additional to this, an extension of the Peres--Horodecki separability criteria for momentum probability distributions is presented in the case of bipartite, asymmetrical, real states.

Abstract: Quantum mechanics famously posits two distinct evolution rules for the state of a system: a deterministic, unitary time evolution under the Schr¨odinger equation, and a probabilistic “collapse” of the wavefunction upon measurement as dictated by the Born rule. The apparent inconsistency of these two dynamical laws – one continuous and one discontinuous – constitutes the quantum measurement problem. This foundational problem, which underlies the emergence of definite outcomes from quantum superpositions, has persisted since the theory’s inception. In this review, we present a comprehensive and rigorous examination of the measurement problem and survey the leading approaches that seek to resolve or circumvent it. We begin by formulating the measurement problem and its conceptual challenges. We then discuss in detail the major interpretations of quantum mechanics and theoretical frameworks addressing the problem: the Copenhagen interpretation, Everett’s many-worlds interpretation, de Broglie–Bohm pilot-wave theory, objective collapse models, the role of decoherence and environment-induced superselection, and epistemic approaches such as QBism. For each interpretation, we describe the core principles and mathematical formalism, assessing how (and whether) it attempts to solve the measurement problem. We also review modern developments and experiments relevant to quantum measurements, including tests of Bell inequalities, observations of decoherence and macroscopic superpositions, weak measurements and quantum eraser experiments, and thought experiments ‘a la Wigner’s friend. We highlight how these results inform the ongoing debate. Finally, we discuss open problems and challenges that remain in fully resolving the measurement problem.

Abstract: The instantaneous nature of quantum entanglement remains one of the most intriguing aspects of quantum mechanics. While the no-signaling theorem prohibits faster-than-light communication, the concept of a finite speed for the collapse of the quantum wavefunction has been a subject of philosophical debate. In this paper, we propose an experimental setup designed to test the speed of wavefunction collapse using entangled photon pairs over a distance of 10 km. By systematically varying the time delay between measurements and analyzing the resulting correlations, we aim to outline a method that could place bounds on the collapse speed without contradicting the no-signaling theorem. We argue that detecting a finite, possibly superluminal, speed of collapse could allow for maintaining realism and locality through high-speed remote synchronization, eliminating the need for hidden variables. We provide a detailed experimental design, including an algorithm and a Python implementation using the Cirq library to simulate the proposed experiment. Our goal is to motivate experimentalists to undertake this test, which could have profound implications for our understanding of quantum mechanics and the nature of reality.

Abstract: Despite its remarkable success in describing microscopic phenomena, quantum mechanics continues to pose unresolved foundational questions concerning measurement, nonlocality, wavefunction collapse, and the nature of physical reality. These issues were highlighted by the EPR paradox1-2, in which Einstein and his co-authors examined the measurement of entangled particles in space-like separation. Quantum mechanics predicts that measuring one particle’s observable instantaneously determines the state of the other, seemingly violating special relativity’s prohibition of faster-than-light influences and suggesting an incomplete description of physical reality. However, Bell’s theorem3-5, along with the Bell-Kochen-Specker theorem6-10 and subsequent experiments, has largely ruled out local hidden variable theories. In this work, I apply the quantum decoherence framework11-13, pioneered by Zeh, Zurek, Joos and Leggett et al. to analyze an EPR-like system using system-environment interactions as a measurement model. I demonstrate that measurement on one entangled particle does not instantaneously collapse the system's wavefunction. Instead, the local wavefunctions of the measured particle and its environment evolve dynamically, while the remote particle’s wavefunction remains unchanged. Environment-induced decoherence selects pointer states and rapidly suppresses quantum correlations through local interactions, giving rise to the appearance of wavefunction collapse. These findings suggest that quantum mechanics can be reconciled with local realism if the wavefunction is treated as an ontic entity, offering a potential path toward a locally realistic quantum theory in alignment with Einstein’s vision.

Abstract: Informational Quantum Gravity (IQG) presents a transformative framework that unifies quantum mechanics (QM), general relativity (GR), and the Standard Model (SM) by redefining reality’s foundation as quantum informational density ρ rather than matter. At its core lies the Primordial Informational Field (PIF), a universal substrate structured by discrete Quantules, where ρ-flows, driven by entropy gradients (Sent), govern the emergence of particles, forces, and spacetime. This equation, ▫ρ-λρ2+μρ3+η∂ρ∂t=Sent∇⋅v+Vunified(ρ,x,t), encapsulates IQG’s dynamics, proposing resolutions to paradoxes like singularities, black hole information loss, and the measurement problem. IQG aligns with frameworks like the Quantum Memory Matrix (QMM), which views space-time as an information reservoir, while extending beyond QMM’s scope with a broader, testable paradigm. Recent QMM experiments lend empirical support to informational physics, enhancing IQG’s relevance. IQG predicts observable effects—gravitational wave distortions (~10⁻³ Hz shifts), cosmological lensing (~10⁻⁵ arcsec), and quantum coherence anomalies—accessible via LIGO, Euclid, and quantum simulators. By recasting the universe as an entropy-driven informational network, IQG offers a unified lens for physics and transformative applications in quantum technologies.

Abstract: We consider a multilevel atom such as an hydrogen atom, interacting with the quantum electromagnetic field, in the dressed ground state of the interacting system. We evaluate by perturbation theory the dressed ground state of the system, within dipole approximation; we investigate and review the effect of the self-dressing of the atom on several field and atomic observables. Specifically, we obtain general expressions of the renormalized electric and magnetic field fluctuations and energy densities around the atom, and analyze their scaling with the distance from the atom, obtaining approximated expressions in the so-called near and far zone. We also investigate nonlocal spatial field correlations around the atom. We stress how the quantities we evaluate can be probed through two- and three-body nonadditive Casimir-Polder dispersion interactions. We also investigate the effect of the self-dressing, i.e. of the virtual transitions occurring in the dressed ground state, on atomic observables, for example the average potential energy of the electron in the nuclear field; this also allows us to obtain a more fundamental quantum basis for the Welton interpretation of the Lamb shift of a ground-state hydrogen atom, in terms of the atomic self-dressing processes.

Abstract: The challenge of the vacuum catastrophe arises from the vast discrepancy between quantum field theoretical predictions and observed vacuum energy density. Using analytic continuation techniques and asymptotic analysis to ensure physical consistency, we explored the Mittag-Leffler function (MLF), a generalized exponential function widely applied in fractional calculus and anomalous diffusion, as a potential framework to address vacuum catastrophe. We computed the MLF-regularized vacuum energy integral, evaluated renormalization group equations, derived modified field equations for different parameter choices, and provided numerical solutions to the modified Friedmann equations to track the evolution of the scale factor. Unlike conventional approaches relying on arbitrary cutoffs and standard QFT predictions, which exhibit uncontrolled growth at high energies, MLF smoothly regulates coupling divergences by naturally attenuating high-energy contributions while preserving Lorentz invariance and renormalization group consistency. The field propagation profile exhibited suppression of high-energy components, consistent with the modified dispersion relation predicted by fractional-order differential formulations. The scale factor evolution indicated a reduced contribution from vacuum energy, aligning with the expectation that MLF diminishes the effective cosmological constant. We found minimal deviations in the cosmic microwave background power spectrum, suggesting that MLF regularization induces subtle modifications to the ΛCDM model. Our findings suggest that the vacuum may follow fractional-order statistical behaviour rather than purely Gaussian statistics, accounting for long-range correlations and memory effects while naturally suppressing high-energy divergences. While not a definitive resolution, MLF regularization represents a significant advancement in addressing the vacuum catastrophe, offering a physically motivated approach to vacuum energy regularization.

Abstract: As we all know, Einstein disagreed with Born's probabilistic interpretation of wave-functions, which collapse abruptly once measurements are performed on the corresponding systems. In the Einstein-Bohr debate, Einstein considered quantum mechanics incomplete. Inspired by Einstein, Bell and his followers intended to complete quantum mechanics within the framework of local realism. Regrettably, deterministic correlations in Einstein's local-realist description of the world are mistaken for "nonlocal-interactions" (non-locality) in the world described by Bell's theorem, which leads to the questionable interpretation of the experimental results obtained by testing Bell inequalities. This article introduces a new principle, the general principle of measurements, which is proved as a mathematical theorem and allows quantum mechanics to be completed within the framework of local realism while keeping the axiomatic definition of a general Hilbert space essentially unchanged. Using disjunction ("or") as the logical relation between orthonormal vectors spanning a given Hilbert space, the completed quantum theory precludes inexplicable collapses of wave-functions and is intuitively comprehensible, thus alleviating much difficulty in understanding quantum mechanics. Among various world views, Einstein's local-realist world view is correct.

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Higher dimensional communications in optical fiber enables new possibilities including increased transmission capacity and hyperentangled state transfer. Mode coupling among channels during transmission however causes interference among channels and limits detection. In classical optical communications, MIMO (modes in modes out) is a means to deal with this issue, however it is not possible to utilize this technology in quantum communications due to power limitations. Principal mode transmission is a another means to deal with mode coupling and signal interference among channels. Conceptually, this can be used in quantum communications with some limitations. In this report, we numerically simulate this process using the time delay method and show how it can be implemented using 2 and 4 higher dimensional quantum states, such as W or GHZ states. These numerical simulations are very illustrative of how the implementation proceeds.

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We show that free QED is equivalent to the continuous-space-and-time limit of Fermi and Bose lattice quantum cellular automata theories derived from quantum random walks satisfying simple symmetry and unitarity conditions. In doing so we define the Fermi and Bose theories in a unified manner using the usual fermion internal space but a boson internal space that is six-dimensional. We show that the reduction to a two-dimensional boson internal space (two helicity states arising from spin-1 plus the photon transversality condition) comes from restricting the quantum cellular automaton theory to positive energies. We briefly examine common symmetries of quantum cellular automata, and how time-reversal symmetry demands the existence of negative-energy solutions. These solutions produce a tension in coupling the Fermi and Bose theories, in which the strong locality of quantum cellular automata seems to require a nonzero amplitude to produce negative-energy states, leading to an unphysical cascade of negative-energy particles. However, we show in a 1D model that by extending interactions over a larger (but finite) range it is possible to exponentially suppress the production of negative-energy particles to the point where they can be neglected.

Abstract: This paper presents a novel theoretical framework that reinterprets the cosmological constant problem through a quantum decay perspective. I propose a time-dependent quantum vacuum decay model wherein vacuum energy density gradually decreases through probabilistic processes, naturally explaining the vast 10120 discrepancy between Quantum Field Theory predictions and observed dark energy values. Beyond addressing this longstanding problem, this model reveals a profound connection between quantum decay and time itself, suggesting time is an emergent phenomenon fundamentally linked to quantum decay rates. This perspective offers elegant interpretations of gravitational time dilation, relativistic time dilation, and the cosmic speed limit without modifying general relativity or quantum mechanics, but by unifying their underlying mechanisms. I demonstrate mathematical correspondence between quantum decay rates and relativistic time dilation formulas, providing a microscopic foundation for macroscopic spacetime phenomena. The theory generates specific, testable predictions for precision atomic clock experiments, black hole observations, and cosmological measurements, potentially resolving tensions in current Lambda Cold Dark Matter model data. This framework bridges quantum mechanics and relativity by establishing a common mechanism governing both the cosmological constant and the nature of time, offering a pathway toward reconciling two pillars of modern physics.

Abstract: Quantum cryptography protocols offering unconditional protection open great rout to full information security in quantum era. Yet, implementing these protocols using the existing fiber networks remains challenging due to high signal losses reducing the efficiency of these protocols to zero. The recently proposed Quantum-protected Control-based Key Distribution (QCKD) addresses this issue by physically controlling interceptable losses and ensuring that leaked quantum states remain non-orthogonal. Here, we present the first in-field development and demonstration of the QCKD over an urban fiber link characterized by substantial losses. Using information-theoretic considerations, we configure the system ensuring security and investigate the interplay between line losses and secret key rates. Our results backed by the statistical analysis of the secret key, confirm QCKD’s robustness under real-world conditions, and establish it as a practical solution for quantum-safe communications over existing fiber infrastructures.

Abstract: The Leggett-Garg inequalities (Phys. Rev. Lett., 1985) involving multi-time correlation functions are widely considered as the touchstone for what is defined as Macro-Realism of the physical world, which constitutes two main criteria: a) a macro-real system is in one of the possible definite discrete physical states at any given time, and b) the possibility of measurements without altering a physical state. There are continuing experimental investigations supposedly testing the consequences of macro-realism, reflected in the Leggett-Garg inequalities. I prove the surprising universal result that the Leggett-Garg inequalities are violated by all dynamical physical systems that respect fundamental conservation laws, and not merely by microscopic and macroscopic quantum systems. Hence, the inequalities are guaranteed to be violated by any conceivable physical system irrespective and independent of the covering theory. The Leggett-Garg inequalities have no place in the real world where ensemble-averaged expectation values and correlation functions bridge the probabilities of microscopic quantum mechanics and the conservation constraints of the macroscopic world.

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Quantum mechanics (QM) is an extremely successful theory, however, there is still no consensus regarding its interpretation. Among the controversies, the quantum classical transitions are the outstanding questions. In this paper, starting from measurement theory, we discuss the role that the precision limit for observation plays in QM and attempt to lubricate the relationship between the precision limit and some unique characters and nature of QM. By reviewing Bohmian mechanics, one of the nonlocal hidden variable theories, we discuss the possibility of restoring determinism in QM. We conclude that it is the existence of the precision limit that makes it impossible to restore determinism in QM, and it is the root that makes QM different from classical physics. Finally, the boundary between the so-called classical and quantum worlds is discussed. We hope these philosophical arguments can provide a kind of epistemic understanding for QM.