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The European Physical Journal C

Dynamics and uncertainty for maximally entangled bipartite system constrained on a helicoid

Asma Bashir, Muhammad Abdul Wasay, Abdulaziz Al-Mogeeth, Quanhui Liu

Published Sep 13, 2022• 2 citations
Publisher

Abstract

Abstract The classical and quantum dynamics of particles constrained on a right helicoid is discussed via Dirac approach. We show how the uncertainty in measurement for observables of maximally entangled system is affected by the total number of constrained particles $$\sigma $$ σ , external magnetic field $$\vec {\mathcal {B}}$$ B → ; as well as by geometric parameters like the pitch $$\rho $$ ρ and the radial position of particles. In doing so we also highlight numeric bounds on the external field strengths to tune both intraparticle and bipartite entanglement and we remark that the bipartite entanglement is more robust to changes in the fields than the intraparticle entanglement, in this framework. We also highlight specific parameter regimes which lead the uncertainty (in measurement) to achieve respective parameter independence and, for a particular subset of commutation relations, the system remains confined in the quantum regime even in the limit $$\sigma \rightarrow \infty $$ σ → ∞ . It is observed that the uncertainties are strongly influenced by the geometric parameters e.g., $$\rho $$ ρ , and the strength of bipartite as well as intraparticle entanglement might be controllable through $$\rho $$ ρ . The energy equation for this setup is obtained and the additional terms are discussed which arise due to quantum correlations, orbit–orbit interaction and the normal Zeeman effect, which leads to the splitting of the energy level into 11 non-degenerate levels. Finally we comment that, a linkage of this phenomenology with Aharonov–Bohm like effect might be possible by strictly confining $$\vec {\mathcal {B}}$$ B → along the central axis of the helicoid.

DOI
10.1140/epjc/s10052-022-10765-4

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Abstract The classical and quantum dynamics of two particles constrained on S1S^1S1 S1 is discussed via Dirac’s approach. We show that when state is maximally entangled between two subsystems, the product of dispersion in the measurement reduces. We also quantify the upper bound on the external field B⃗\vec {B}B B→ such that B⃗≥B⃗upper\vec {B}\ge \vec {B}_{upper }B≥Bupper​ B→≥B→upper implies no reduction in the product of dispersion pertaining to one subsystem. Further, we report on the cut-off value of the external field B⃗cutoff\vec {B}_{cutoff }Bcutoff​ B→cutoff , above which the bipartite entanglement is lost and there exists a direct relationship between uncertainty of the composite system and the external field. We note that, in this framework it is possible to tune the external field for entanglement/unentanglement of a bipartite system. Finally, we show that the additional terms arising in the quantum Hamiltonian, due to the requirement of Hermiticity of operators, produce a shift in the energy of the system.
Abstract We formulate the variance-based uncertainty relations (URs) via the Robertson’s inequality, for a 2-particle entangled system constrained on a torus and subject to a stationary magnetic field B⃗\mathcal {\vec {B}}B B → . We explore the system’s parameter space and show that these new URs have field-tunable uncertainty bounds. Our analysis reveals that A⃗\mathcal {\vec {A}}A A → (vector potential) induces a phase shift in the state, due to the Aharonov–Bohm effect, leading to a perturbed system dynamics which results in asymmetric product of variance ( POV\mathcal {POV}POV POV ). Additionally, we give the critical range of A⃗\mathcal {\vec {A}}A A → and B⃗\mathcal {\vec {B}}B B → where the system acts as an entanglement amplifier; this amplification is also discussed under various geometric parameters. The possibility of reducing the POV\mathcal {POV}POV POV of the conjugate pair [q, p] below the known benchmark value by the Generalized Uncertainty Relation (GUR) is also demonstrated. Finally, we check the susceptibility of state coherence to B⃗\mathcal {\vec {B}}B B → by saturating the angular momentum uncertainty relation and identify the critical coherence value Bc{\mathcal {B}}_cBc​ B c such that when B≠Bc{\mathcal {B}}\ne {\mathcal {B}}_cB=Bc​ B ≠ B c , the state decoheres.
We explore the dynamical behaviors of the measurement uncertainty and quantum correlation for a vertical quantum-dot system in the presence of magnetic field, including electron-electron interaction and Coulomb-blocked systems. Stemming from the quantum-memory-assisted entropic uncertainty relation, the uncertainty of interest is associated with temperature and parameters related to the magnetic field. Interestingly, the temperature has two kinds of influences on the variation of measurement uncertainty with respect to the magnetic-field-related parameters. We also discuss the relation between the lower bound of Berta et al. and the quantum discord. It is found that there is a natural competition between the quantum discord and the entropy min Π i B S Π i B ( ρ A | B ) . Finally, we bring in two improved bounds to offer a more precise limit to the entropic uncertainty.
In a system of two charge-qubits that are initially prepared in a maximally entangled Bell's state, the dynamics of quantum memory-assisted entropic uncertainty, purity, and negative entanglement are investigated. Isolated external cavity fields are considered in two different configurations: coherent-even coherent and even coherent cavity fields. For different initial cavity configurations, the temporal evolution of the final state of qubits and cavities is solved analytically. The effects of intrinsic decoherence and detuning strength on the dynamics of bipartite entropic uncertainty, purity and entanglement are explored. Depending on the field parameters, nonclassical correlations can be preserved. Nonclassical correlations and revival aspects appear to be significantly inhibited when intrinsic decoherence increases. Nonclassical correlations stay longer and have greater revivals due to the high detuning of the two qubits and the coherence strength of the initial cavity fields. Quantum memory-assisted entropic uncertainty and entropy have similar dynamics while the negativity presents fewer revivals in contrast.
The dynamics of a spin-(1/2) neutral particle possessing electric- and magnetic-dipole moments interacting with external electric and magnetic fields in noncommutative coordinates is obtained. Noncommutativity of space is interposed in terms of a semiclassical constrained Hamiltonian system. The relation between the quantum phase acquired by a particle interacting with an electromagnetic field and the (semi)classical force acting on the system is examined and generalized to establish a formulation of the quantum phases in noncommutative coordinates. The general formalism is applied to physical systems yielding the Aharonov-Bohm, Aharonov-Casher, He-McKellar-Wilkens and Anandan phases in noncommutative coordinates. Bounds for the noncommutativity parameter θ are derived comparing the deformed phases with the experimental data on the Aharonov-Bohm and Aharonov-Casher phases.
In this paper, we examine the dynamics of Entropic Uncertainty (EU) and concurrence entanglement (CN) in a two-qubit superconducting system influenced by external parameters such as energy biases, coupling strength, and an oscillating external magnetic field. The Hamiltonian includes a Josephson junction coupling term along the [Formula: see text]-direction. Our results show an inverse relationship between EU and CN: stronger coupling reduces EU and enhances CN, while higher energy biases increase EU and decrease CN. The intrinsic magnetic field strength modulates EU and CN, with higher magnetic field reducing EU and enhancing CN at specific phase angles. Temperature variations significantly impact quantum measures, with higher temperatures increasing EU and reducing CN, indicating that lower temperatures favor entanglement and minimize uncertainty. These findings highlight the sensitivity of quantum properties to external parameters, providing optimization for the quantum state control in superconducting qubit systems.