International Journal of Theoretical Physics最新文献

The purpose of this paper is to explore how to teleport a low-dimensional (two-dimensional) arbitrary unknown two-qubit entangled state through the high-dimensional entangled states constituting the quantum channel. Firstly, we propose a scheme for teleporting an arbitrary unknown two-qubit entangled state via two three-dimensional maximally entangled two-qutrit states as the quantum channel. In this scheme, the sender performs two non-symmetric basis measurements on his own particles, and the receiver must make relevant unitary operation against the sender’s different measurement results to recover the original unknown state. Then, the above maximally entangled quantum channel is replaced by two high-dimensional non-maximally entangled two-particle states, the arbitrary unknown two-qubit state is teleported in such a way that it can be probabilistically reconstructed through introducing auxiliary qubit and performing appropriate operations. We give the success probability of the schemes, and the analysis shows that the scheme based on non-maximally entangled channel is a generalization of the previous scheme. Furthermore, the above schemes can be directly generalized to the case of two arbitrary high-dimensional entangled two-particle states acting as the quantum channel.

In this study, we investigate a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in non-linear form of f(Q) gravity with observational constraints. We solved the modified Einstein’s field equations with a viscous fluid source and got a hyperbolic solution. First, we apply MCMC analysis to the cosmic chronometer (CC), Baryon Acoustic Oscillation (BAO) and Pantheon datasets to place observational constraints on the model parameters. Using constrained values of model parameters, we study the behavior of cosmological parameters, such as the Hubble parameter H, the deceleration parameter q, and the equation of state (EoS) parameter (omega _{v}) with the skewness parameter (delta _{v}) for the viscous fluid. In addition, we perform the Om diagnostics and statefinder analysis to categorize dark energy models. Also, we studied cosmographic series coefficients to explore the whole evolution of the derived universe model. We estimated the current age of the universe as (t_{0}approx 13.8) Gyrs. We obtained a quintessential and ever-accelerating model with bulk viscosity fluid.

In this paper, we investigate the interference and Bell states of a q-deformed harmonic oscillator. The Wigner functions of the interference states and the four Bell states are calculated and discussed.

The internal energy and heat capacity of a two-dimensional electron gas in a half-filled Landau subband for a Gaussian distribution of the density of states are studied by analytical and numerical methods. Within the limits of low (:{k}_{B}T<<{Gamma:}) and high (:{k}_{B}T>>{Gamma:}) temperatures, analytical formulas for internal energy and heat capacity were found. The reason for the appearance of a peak in the temperature dependences of heat capacity is discussed. It is shown that in the region of (:{k}_{B}Tge:{Gamma:}), saturation of the internal energy of the electron gas is observed due to the narrowness of the subband width. The analytical results are graphically compared with the numerical data.

The current study delves into a novel class of static, spherically symmetric anisotropic fluid solutions to the Einstein field equations, aimed at elucidating the nature of the dark matter halo. To construct the model, we have used the phenomenological flat rotational curve condition and a specific expression for the radial pressure. The analytic solution produces well-behaved metric potentials and accurately reproduces the true mass of the Milky Way (MW) galaxy. Our findings indicate that the gravitational influence in the halo is inherently attractive. The circular orbits in the halo in which the particles are moving are stable. The halo is Newtonian in nature and filled with non-exotic dust fluid.

This paper presents the first negative-order matrix AKNS flow, derived by associating a Lax pair containing a first-order pole in the spectral parameter with the matrix AKNS spectral problem. The corresponding Darboux transformation is constructed within the AKNS framework. Starting from a seed solution, a class of exact and explicit solutions to the nonlinear negative-order model is generated via a single application of the derived Darboux transformation.

Random numbers are a central problem in the disciplines of scientific simulations, cryptography, randomized algorithms, and secure communications. The software-generated pseudorandom bit sequence is fast enough but does not meet the required randomness quality requirements. For this reason, more intensive physical hardware techniques are being developed to generate a real random sequence. This study presented a method for producing quantum truly random bit sequences as the best physical implementation of qubits. The proposed algorithm is implemented in an IBM Quantum Experience (IBMQ) quantum computer. Implementation is done through the IBM software platform QISKit. Quantum state rotation gate X, rotation gate Z, and phase shift gate are used. It performs the superposition of the initial state and gives random numbers on measured. QISKit SDK qasm simulator, real chip seven qubit superconductivity based IBMQ 127 qubit quantum computer is used to run the suggested quantum circuit. The proposed algorithm’s accuracy, validity, and randomness applicability have been validated by restart experiments, autocorrelation analysis, National Institute of Standards and Technology (NIST) NIST SP 800-90B and NIST SP 800 − 22 verified with low gate requirements. The proposed method can be an attractive and appropriate choice in the Noisy Intermediate Scale Quantum (NISQ) technology age. Modern-generation noisy quantum computers can mimic the noisy environment of quantum channels while at the same time acting as a testbed to see how the protocol works on real hardware.

This study investigates the Klein-Gordon (KG) oscillator equation in the spacetime of a cosmic string under the influence of rainbow gravity, an external magnetic field, and a position-dependent mass (PDM). An analytical solution of the KG oscillator is derived, and the resulting energy equation is used to compute the numerical energy levels of charmonium and bottomonium for two types of rainbow functions. The computed values show good agreement with experimental data. Furthermore, the energy equation is used to evaluate the partition function, from which various thermodynamic properties of charmonium and bottomonium are derived. For rainbow function 1, increasing the inverse temperature parameter (:beta:) results in a decrease in the partition function, internal energy, and entropy, while the free energy increases. The specific heat capacity exhibits a peak before declining. For rainbow function 2, the partition function and free energy increase with (:beta:), whereas internal energy and entropy decrease. The specific heat capacity again displays a non-monotonic behavior, rising to a maximum and then decreasing as (:beta:) increases. These results reveal how rainbow gravity, magnetic field, and PDM collectively influence the quantum and thermodynamic characteristics of relativistic quark systems.

The experimental verification of multipartite entangled states is essential for advancing quantum information processing. Entanglement witnesses (EWs) provide a widely used and experimentally accessible approach for detecting genuinely multipartite entangled states. In this work, we theoretically derive the entanglement witness for the four-qubit Dicke state and experimentally evaluate it on two distinct IBM 127-qubit Quantum Processing Units (QPUs), namely ibm_sherbrooke and ibm_brisbane. A negative expectation value of the witness operator serves as a sufficient condition for confirming genuine multipartite entanglement. We report the maximum (negative) values of the witness achieved on these QPUs as (-0.178 pm 0.009) and (-0.169 pm 0.002), corresponding to two different state preparation protocols. Additionally, we theoretically investigate the effect of various noise channels on the genuine entanglement of a four-qubit Dicke state using the Qiskit Aer simulator. We show the behavior of the EW constructed under the assumption of Markovian and non-Markovian amplitude damping and depolarizing noises, bit-phase flip noise, and readout errors. We also investigate the effect of varying thermal relaxation time on the EW, depicting a bound on the (T_1) time required for successful generation of a Dicke State on a superconducting QPU.

Common cause completeness (CCC) is a philosophical principle that asserts that if we consider two positively correlated events, then it evokes a common cause event. The principle is due to H. Reichenbach and has mostly been studied in Boolean algebras and orthomodular lattices (quantum logics). The results published so far bring about a question of whether there is a small (countable) Boolean algebra with CCC. In this note, we construct such a Boolean algebra. Since finite Boolean algebras can satisfy CCC only trivially, this example is a smallest possible meaningful example.