Abstract In the quantized field formalism, using Kramers–Henneberger unitary transformation as the semi-classical counterpart of Block–Nordsieck transformation, the dynamics of entanglement during the low energy scattering processes in bi-partite systems at the presence of a laser beam fields are studied. The stationary-state Schrodinger equation for the quantum scattering process is obtained for such systems. Then, using partial wave analysis, we introduce a new form of entanglement fidelity considering the effect of high-intensity laser beam fields. The effective potential of hot quantum plasma including plasmon and quantum screening effects is used to obtain the entanglement fidelity ratio as a function of the laser amplitude, and plasmon and Debye length parameters for the elastic electron-ion collisions. It is shown that the plasma free electrons oscillations under interaction with laser beam fields improve the correlations between charged particles and consequently lead to the increase in the system entanglement.
Abstract In the quantized field formalism, using Kramers–Henneberger unitary transformation as the semi-classical counterpart of Block–Nordsieck transformation, the dynamics of entanglement during the low energy scattering processes in bi-partite systems at the presence of a laser beam fields are studied. The stationary-state Schrodinger equation for the quantum scattering process is obtained for such systems. Then, using partial wave analysis, we introduce a new form of entanglement fidelity considering the effect of high-intensity laser beam fields. The effective potential of hot quantum plasma including plasmon and quantum screening effects is used to obtain the entanglement fidelity ratio as a function of the laser amplitude, and plasmon and Debye length parameters for the elastic electron-ion collisions. It is shown that the plasma free electrons oscillations under interaction with laser beam fields improve the correlations between charged particles and consequently lead to the increase in the system entanglement.
Entanglement is an inherently quantum phenomenon, and particle-particle scattering can generate quantum entanglement depending on the interaction potential between the two particles. The theoretical evaluation of the entanglement generated during particle-particle scattering is carried out using entanglement fidelity. The particle-particle interaction potential is modified in the presence of other particles, such as those in a plasma environment, and under an external electric field induced by a laser. Consequently, quantum entanglement becomes a function of plasma and laser parameters. In this study, a dense two-temperature plasma environment consisting of electrons and ions is considered, which can exhibit either classical or quantum behavior, including quantum diffraction and exchange symmetry, while an external electric field (laser) is also present. The interaction of the laser with plasma particles excites oscillations and modifies the plasma dynamics, all of which can be incorporated into the effective particle-particle interaction potential. Therefore, the effects of plasma parameters, such as temperature and density, as well as laser intensity, on entanglement can be directly analyzed. The results show that low collision energy, low plasma temperature, high particle density (or short Debye length), and specific ranges of laser intensity lead to an enhancement of quantum entanglement. Furthermore, in an electron-ion plasma, the electron temperature plays a much more significant role in entanglement dynamics than the ion temperature.
The influence of electron-exchange and quantum screening on the collisional entanglement fidelity for the elastic electron–ion collision is investigated in degenerate quantum plasmas. The effective Shukla–Eliasson potential and the partial wave method are used to obtain the collisional entanglement fidelity in quantum plasmas as a function of the electron-exchange parameter, Fermi energy, plasmon energy and collision energy. The results show that the quantum screening effect enhances the entanglement fidelity in quantum plasmas. However, it is found that the electron-exchange effect strongly suppresses the collisional entanglement fidelity. Hence, we have found that the influence of the electron-exchange reduces the transmission of quantum information in quantum plasmas. In addition, it is found that, although the entanglement fidelity decreases with an increase of the Fermi energy, it increases with increasing plasmon energy in degenerate quantum plasmas.
The electron-exchange and shielding on the entanglement fidelity for the elastic electron-ion collision is investigated in strong quantum recoil semiconductor plasmas. The effective Shukla-Eliasson potential and the partial wave method are employed to obtain the collisional entanglement fidelity as a function of the electron-exchange parameter, collision energy, Fermi energy, and plasmon energy. The result shows that the influence of electron-exchange suppresses the transmission of quantum information in strong quantum recoil semiconductor plasmas. It is also found that the collisional entanglement fidelity decreases with an increase of the Fermi energy. Additionally, the collisional entanglement fidelity increases with increasing plasmon energy.
In the present work, we present an investigation on quantum entanglement of the two-electron helium atom immersed in weakly coupled Debye plasmas, modeled by the Debye-Hückel, or screened Coulomb, potential to mimic the interaction between two charged particles inside the plasma. Quantum entanglement is related to correlation effects in a multi-particle system. In a bipartite system, a measurement made on one of the two entangled particles affects the outcome of the other particle, even if such two particles are far apart. Employing wave functions constructed with configuration interaction B-spline basis, we have quantified von Neumann entropy and linear entropy for a series of He 1,3Se and 1,3Po states in plasma-embedded helium atom.
Surface plasma waves arise from the collective oscillations of billions of electrons at the surface of a metal in unison. The simplest way to quantize these waves is by direct analogy to electromagnetic fields in free space, with the surface plasmon, the quantum of the surface plasma wave, playing the same role as the photon. It follows that surface plasmons should exhibit all of the same quantum phenomena that photons do, including quantum interference and entanglement. Unlike photons, however, surface plasmons suffer strong losses that arise from the scattering of free electrons from other electrons, phonons, and surfaces. Under some circumstances, these interactions might also cause “pure dephasing,” which entails a loss of coherence without absorption. Quantum descriptions of plasmons usually do not account for these effects explicitly, and sometimes ignore them altogether. In light of this extra microscopic complexity, it is necessary for experiments to test quantum models of surface plasmons. In this thesis, I describe two such tests that my collaborators and I performed. The first was a plasmonic version of the Hong-Ou-Mandel experiment, in which we observed two-particle quantum interference between plasmons with a visibility of 93 ± 1%. This measurement confirms that surface plasmons faithfully reproduce this effect with the same visibility and mutual coherence time, to within measurement error, as in the photonic case. The second experiment demonstrated path entanglement between surface plasmons with a visibility of 95 ± 2%, confirming that a path-entangled state can indeed survive without measurable decoherence. This measurement suggests that elastic scattering mechanisms of the type that might cause pure dephasing must have been weak enough not to significantly perturb the state of the metal under the experimental conditions we investigated. These two experiments add quantum interference and path entanglement to a growing list of quantum phenomena that surface plasmons appear to exhibit just as clearly as photons, confirming the predictions of the simplest quantum models.
Ultrafast strong-field laser--plasma physics is shown to offer a promising framework for relativistic nonlinear quantum electrodynamics (QED). As one of its key advantages, this approach to relativistic nonlinear QED does not require an external beam of relativistic particles. Instead, high-energy electrons are produced in this setting as a part of ultrafast strong-field laser--plasma interactions. An intense ultrashort laser pulse generates and accelerates dense electron bunches to relativistic energies, giving rise to photon-pair emission confined to the nanometer scale in space and the attosecond scale in time. As a lowest-order nonlinear QED process, relativistic electrons in laser-driven plasmas are shown to give rise to attosecond bursts of two-photon emission, providing an ultrabroadband source of correlated photon pairs. As a physically insightful estimate, the rate of this two-photon emission is expressed via a product $ α^2 γω_{turn}$, where α is the fine-structure constant, γ is the Lorentz factor, and $ ω_{turn}$ is the local relativistic curvature frequency. Photon pairs with strongest correlations, providing a resource for photon entanglement, are emitted at a much lower rate, estimated as $ α^2 γ^2 ω_{turn} E_{\perp} /E_S$, where E⊥ is the laser electromagnetic field, determining the transverse Lorentz force, and ES is the Schwinger critical field. Our study offers a clear guidance on how quantum aspects of laser-driven relativistic plasma electrodynamics can be isolated from their classical counterparts, enabling a physically justifiable approach to the analysis of nonlinear QED phenomena in complex laser--plasma interactions driven by ultrashort high-intensity laser pulses.