arXiv subjects

Mehdi Golshani

Publications and source records attributed to Mehdi Golshani.

At least 19 recordsLinked to original sources

arXiv2025

Quantum Objects

In this paper, we suggest an alternative interpretation for the quantum state vector, which, by considering temporal parts for physical objects, aims to give an intelligible account of measurement problem in quantum mechanics. We examine the capacity of this interpretation as for explaining three measurement problems: the problem of outcome, the problem of statistics and the problem of effect. We argue that, this interpretation of the state vector, while providing a satisfactory account, as rationally plausible as its rivals, for the measurement problem, shows yet another limitation of our perceptual experience, i.e. our inability to perceive unsharp reality.

physics.hist-ph↗

arXiv2023

Non-local interference in arrival time

Although position and time have different mathematical roles in quantum mechanics, with one being an operator and the other being a parameter, there is a space-time duality in quantum phenomena: a lot of quantum phenomena that were first observed in the spatial domain were later observed in the temporal domain as well. In this context, we propose a modified version of the double-double-slit experiment using entangled atom pairs to observe a non-local interference in the arrival time distribution, which is analogous to the non-local interference observed in the arrival position distribution. However, computing the arrival time distribution in quantum mechanics is a challenging open problem, and so to overcome this problem we employ a Bohmian treatment. Based on this approach, we numerically demonstrate that there is a complementary relationship between the one-particle and two-particle interference visibilities in the arrival time distribution, which is analogous to the complementary relationship observed in the position distribution. These results can be used to test the Bohmian arrival time distribution in a strict manner, i.e., where the semiclassical approximation breaks down. Moreover, our approach to investigating this experiment can be applied to a wide range of phenomena, and it seems that the predicted non-local temporal interference and associated complementary relationship are universal behaviors of entangled quantum systems that may manifest in various phenomena.

quant-ph↗

arXiv2023

Can the double-slit experiment distinguish between quantum interpretations?

Despite the astonishing successes of quantum mechanics, due to some fundamental problems such as the measurement problem and quantum arrival time problem, the predictions of the theory are in some cases not quite clear and unique. Especially, there are various predictions for the joint spatiotemporal distribution of particle detection events on a screen, which are derived from different formulations and interpretations of the quantum theory. Although the differences are typically small, our studies show that these predictions can be experimentally distinguished by an unconventional double-slit configuration, which is realizable using present-day single-atom interferometry. This experiment would enrich our understanding of the foundations of quantum mechanics.

quant-ph↗

arXiv2023

On the gravitization of quantum mechanics and wave function reduction in Bohmian quantum mechanics

The main topic of this paper is using Einstein's equivalence principle in the description of the gravity-induced wave function reduction in the framework of Bohmian causal quantum theory. However, such concept has been introduced and explored by Penrose for the standard quantum mechanics, but the capabilities of Bohmian quantum mechanics makes it possible to get some of results more clearly. In this regard, the critical mass for transition from the quantum world to the classical world, the reduction time of the wave function and the temperature that corresponds to the Unruh temperature will be obtained by applying Einstein's equivalence principle for the quantum motion of particle.

quant-ph↗

arXiv2022

An analogical model for the stationary black holes by the flow field of space-time fluid around a 3-dimensional point sink

Recent researches suggest an analogy between the theory of general relativity (GR) and fluid dynamics. As a result of this analogy, the Navier-Stokes equations and Einstein field equations are the same, and it is possible to study the properties of space-time by using fluid mechanics. In this paper, we present a new model to describe gravitational phenomena by an inviscid and compressible fluid called space-time fluid (STF). The analogy method is used to obtain the gravity field of both static and rotating masses from the flow field of STF around static and rotating point sinks. In addition, event horizons and the ergosphere of stationary black holes are defined based on our STF model. Then, we compare hydrodynamic forces exerted on a test particle with gravitational forces in the gravitoelectromagnetic approximation of the GR. As a natural consequence, it is shown that inertial and gravitational masses are equivalent in this analogy. Finally, using the aspect of fluid dynamics, Mach's principle, weak equivalence principle, and information discontinuity on the event horizon are discussed.

gr-qc↗

arXiv2020

On the dynamics of gravity induced wave function reduction

In this study, we use the concept of Bohmian trajectories to present a dynamical and deterministic interpretation for the gravity induced wave function reduction. We shall classify all possible regimes for the motion of a particle, based on the behavior of trajectories in the ensemble and under the influence of quantum and gravitational forces. In the usual approaches all information are obtained from the wave function evolution. But, on the basis of Bohm's deterministic quantum theory, we can investigate the motion of particle during the reduction processes. This leads to analytical and numerical results for the reduction time and equation of motion of the particle. In this regard, a new meaning will be provided for the reduction time.

quant-ph↗

arXiv2020

Modified Bohmian quantum potential due to the second quantization of Schrodinger equation

A causal interpretation of the quantum world needs second quantization in order to cover phenomena like creation and annihilation of particles, and this leads to quantum field theory. The causal effects of the second quantization can be described through a new quantum potential. In this article we have dealt with the second quantization of Schrodinger and its effects on the path of a particle. This generalization leads to a modified Schrodinger which affects the particle through a modified quantum potential and a new term in the continuity equation. We have shown that these effects can provide a framework for the explanation of the creation and annihilation phenomena and other effects of quantum field theory on the development of a particle.

quant-ph↗

arXiv2020

A geometric look at the objective gravitational wave function reduction

In ref [1], a criterion has been derived for the objective wave function reduction through the Shrödinger-Newton equation. In this paper, we shall derive that criterion by using the concept of Bohmian trajectories. This study has two consequences. First, providing a geometric perspective on the problem of wave function reduction and the other, representing the role of quantum force and gravitational force in the reduction process.

quant-ph↗

arXiv2020

Gravitational reduction of the wave function based on Bohmian quantum potential

In objective gravitational reduction of the wave function of a quantum system, the classical limit of the system is obtained in terms of the objective properties of the system. On the other hand, in Bohmian quantum mechanics the usual criterion for getting classical limit is the vanishing of the quantum potential or the quantum force of the system, which suffers from the lack of an objective description. In this regard, we investigated the usual criterion of getting the classical limit of a free particle in Bohmian quantum mechanics. Then we argued that how it is possible to have an objective gravitational classical limit related to the Bohmian mechanical concepts like quantum potential or quantum force. Also we derived a differential equation related to the wave function reduction. An interesting connection will be made between Bohmian concepts and gravitational concepts.

quant-ph↗

arXiv2019

Impact of nonideal cycles on the efficiency of quantum heat engines

Given a quantum heat engine that operates in a cycle that reaches maximal efficiency for a time-dependent Hamiltonian H(t) of the working substance, with overall controllable driving H(t) = g(t) H, we study the deviation of the efficiency from the optimal value due to a generic time-independent perturbation in the Hamiltonian. We show that for a working substance consisting of two two-level systems, by suitably tuning the interaction, the deviation can be suppressed up to the third order in the perturbation parameter-and thus almost retaining the optimality of the engine.

quant-ph↗

arXiv2019

Theory of cyborg: a new approach to fish locomotion control

Cyborg in the brain-machine interface field has attracted more attention in recent years. To control a creature via a machine called cyborg method, three stages are considerable: stimulation of neurons, neural response, and the behavioral reaction of the subject. Our main concern was to know how electrical stimulation induces neural activity and leads to a behavioral response. Additionally, we were interested to explore which type of electrical stimulation is optimal from different aspects such as maximum response with minimum induction stimulus field, minimum damage of the tissue and the electrode, reduction of the noxiousness of stimuli or pain in the living creature. In this article, we proposed a new model for the induction of neural activity led to locomotion responses through electrical stimulation. Furthermore, based on this model, we developed a new approach of electrical neural stimulation to provide a better locomotion control of living beings. This approach was verified through the empirical data of fish cyborg. We stimulated the fish brain by use of an ultra-high frequency signal which careered by a random low frequency. According to our model, we could control the locomotion of fish in a novel and innovative way. In this study, we categorized the different cyborg methods based on the nervous system areas and the stimulation signal properties to reach the better and optimal behavioral control of creature. According to this, we proposed a new stimulation method theoretically and confirmed it experimentally.

physics.bio-ph↗

arXiv2019

A new method of brain stimulation at ultra-high frequency

Nerve stimulation via micro-electrode implants is one of the neurostimulation approaches which is used frequently in the medical treatment of some brain disorders, neural prosthetics, brain-machine interfaces and also in the cyborg. In this method, the electrical stimulation signal can be categorized by the frequency band: low frequency, high frequency, and ultra-high frequency. The stimulation should be less destructive, more smooth, and controllable. In this article, we present a brief description of the mechanism underlying the ultra-high frequency stimulation. In the flowing, from an informatics perspective, we propose a state-of-the-art, low destructive, and highly efficient stimulation method at the low amplitude ultra-high frequency signal. In this method, we have tried to reduce the adaptation of the nerve system by modulating the stimulation signal via a low frequency rectangular random wave. By this method, we could reach the "almost zero discharge" with minimum destructive effect in the experimental test on the fish nervous system.

physics.bio-ph↗

arXiv2019

Classicalization of Quantum State of Detector by Amplification Process

It has been shown that a macroscopic system being in a high-temperature thermal coherent state can be, in principle, driven into a non-classical state by coupling to a microscopic system. Therefore, thermal coherent states do not truly represent the classical limit of quantum description. Here, we study the classical limit of quantum state of a more relevant macroscopic system, namely the pointer of a detector, after the phase-preserving linear amplification process. In particular, we examine to what extent it is possible to find the corresponding amplified state in a superposition state, by coupling the pointer to a qubit system. We demonstrate quantitatively that the amplification process is able to produce the classical limit of quantum state of the pointer, offering a route for a classical state in a sense of not to be projected into a quantum superposition state.

quant-ph↗

arXiv2018

Some clarifications on the relation between Bohmian quantum potential and Mach's principle

Mach's principle asserts that the inertial mass of a body is related to the distribution of other distant bodies. This means that in the absence of other bodies, a single body has no mass. In this case, talking about motion is not possible, because the detection of motion is possible only relative to other bodies. But in physics we are faced with situations that are not fully Machian. As in the case of general theory of relativity where geodesics exist in the absence of any matter, the motion has meaning. Another example which is the main topic of our discussion, refers to Bohmian quantum mechanics, where the inertial mass of a single particle does not vanish, but is modified. We can call such situations in which motion or mass of a single particle has meaning, pseudo-Machian situations. In this paper, we use the Machian or pseudo-Machian considerations to clarify under what circumstances and how a Machian effect leads us to Bohmian quantum mechanics. Then, we shall get the Bohmian quantum potential and its higher order terms for the Klein-Gordon particle through Machian considerations, without using any quantum mechanical postulate or operator formalism.

quant-ph↗

arXiv2018

On variational principle and canonical structure of gravitational theory in double-foliation formalism

In this paper, we analyze the variation of the gravitational action on a bounded region of spacetime whose boundary contains segments with various characters, including null. We develop a systematic approach to decompose the derivative of metric variations into orthogonal and tangential components with respect to the boundary and express them in terms of variations of geometric objects associated with the boundary hypersurface. We suggest that a double-foliation of spacetime provides a natural and useful set-up for treating the general problem and clarifies the assumptions and results in specialized ones. In this set-up, we are able to obtain the boundary action necessary for the variational principle to become well-posed, beside the canonical structure of the theory, while keeping the variations quite general. Especially, we show how one can remove the restrictions imposed on the metric variations in previous works due to the assumption that the boundary character is kept unaltered. As a result, we find that on null boundaries a new canonical pair which is related to the change in character of the boundary. This set-up and the calculation procedure are stated in a way that can be applied to other more generalized theories of gravity.

gr-qc↗

arXiv2018

Ramsey Interferometers as a test for the correction to quantum mechanics

By applying the basic concept of the density matrix in an open quantum system and modification of quantum mechanics, we derive Kossakowski-Lindblad equation and different properties of this equation are reviewed. Next, a pedagogical approach is used to present Ramsey's trick for linear modification of the quantum mechanics. We discuss how an open quantum mechanics or its modification changes the fraction of excited states in Ramsey Interferometers.

quant-ph↗

arXiv2018

Unifying relativity and classical dynamics

Relativity and classical dynamics, as defined so far, form distinct parts of classical physics and are formulated based on independent principles. We propose that the formalism of classical dynamics can be considered as the theoretical foundation of the current theory of relativity and may be employed for exploring possibilities beyond the current theory. We show that special-relativistic kinematics, including universality of the speed of massless particles relative to inertial frames, is a consequence of the formalism of classical dynamics, with no assumptions other than spacetime point transformations and Euclidean geometry of space in inertial frames. We discuss that energy-independent velocity is a general concept in classical dynamics, applicable even to massive objects, in appropriate canonical coordinates. The derivation of Lorentz symmetry is inherently local and allows the speed of massless particles (relative to local inertial frames) to vary with space and time globally, which may provide a theoretical foundation for variable speed of light cosmology. We obtain no kinematical scales other than the light-speed, specially no scale of energy or momentum as has been suggested in some quantum gravity investigations. We argue that this is a consequence of spacetime point transformations making the momentum space linear, and a possible second scale must require non-point transformations as a necessary condition, which seems compatible with the notion of relative locality in curved momentum space.

physics.gen-ph↗

arXiv2017

Fluctuation relation for heat exchange in Markovian open quantum systems

A fluctuation relation for the heat exchange of an open quantum system under a thermalizing Markovian dynamics is derived. We show that the probability of that the system absorbs an amount of heat from its bath, at a given time interval, divided by the probability of the reverse process (releasing the same amount of heat to the bath) is given by an exponential factor which depends on the amount of heat and the difference between the temperatures of the system and the bath. We also argue that the probability of the violation of the second law of thermodynamics (here in the form of net heat transfer from a cold system to its hot bath) drops exponentially with both the amount of heat and the temperature differences.

quant-ph↗