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.
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.
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.
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.
Fast electrons in partially ionized plasmas lose energy through inelastic collisions with bound electrons. While the mean energy loss is well described by stopping-power theory, fluctuations associated with discrete excitation and ionization events produce energy straggling and an additional longitudinal diffusion in momentum space. We incorporate this effect into fast-electron kinetics through a derived Fokker-Planck operator whose coefficients are obtained from ab initio quantum many-body simulations. We demonstrate that neglecting inelastic energy diffusion in partially ionized D-Ar plasmas can underestimate primary runaway-electron generation by several orders of magnitude.
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.
We investigate the effect of magnetic field and charge noise on the generation of entanglement between two Heisenberg exchange-coupled electron spins in a double quantum dot. We focus on exchange-driven evolution that would ideally take an initial unentangled tensor product state to a maximally entangled state in the absence of noise. The presence of noise obviously adversely affects the attainment of maximal entanglement, which we study quantitatively and exactly. To quantify the effects of noise, we calculate two-qubit coherence times and entanglement fidelity, both of which can be extracted from simulations or measurements of the return probability as a function of interaction time, i.e., the time period during which the exchange coupling remains effective between the two spins. We perform these calculations for a broad range of noise strengths that includes the regime of recent experiments. We find that the two types of noise reduce the amount of entanglement in qualitatively distinct ways and that, although charge noise generally leads to faster decoherence, the relative importance of the two types of noise in entanglement creation depends sensitively on the strength of the exchange coupling. Our results can be used to determine the level of noise suppression needed to reach quantum error correction thresholds. We provide quantitative guidance for the requisite noise constraints necessary to eventually reach the >99 fidelity consistent with the quantum error correction threshold.