arXiv subjects

E. Park

Publications and source records attributed to E. Park.

6 recordsLinked to original sources

arXiv2026

Revealing Laser and Electron Beam Evolution in 10-GeV-class Laser-Plasma Accelerators

Guiding relativistically intense laser pulses in low-density plasmas enables extended acceleration lengths in laser-plasma accelerators (LPAs), allowing for the production of multi-GeV electron beams. Quantitative interpretation of such experiments is often limited by substantial uncertainties in key plasma parameters, particularly the transverse density profile of hydrodynamic optically field-ionized channels. Distinct plasma density distributions can produce similar terminal beam energies, complicating efforts to infer the underlying interaction physics from measurements at the accelerator exit alone. By combining longitudinally resolved electron beam diagnostics with independent measurements of laser spectral evolution in a 10 GeV LPA, we establish a multi-observable constraint on plasma density profiles. Once plasma downramps are taken into account, excellent agreement is observed with simulation over the entire accelerator length for two plasma channel sizes. The validated simulations indicate that extending the accelerator length to 65 cm would increase the electron beam energy to 15 GeV. They also point the way to achieving $\sim$20 GeV electron beams in $\sim$70 cm via linear matching using the same 24 J laser energy.

physics.acc-ph↗

arXiv2024

A Primal Staggered Discontinuous Galerkin Method on Polytopal Meshes

This paper introduces a novel staggered discontinuous Galerkin (SDG) method tailored for solving elliptic equations on polytopal meshes. Our approach utilizes a primal-dual grid framework to ensure local conservation of fluxes, significantly improving stability and accuracy. The method is hybridizable and reduces the degrees of freedom compared to existing approaches. It also bridges connections to other numerical methods on polytopal meshes. Numerical experiments validate the method's optimal convergence rates and computational efficiency.

math.NA↗

arXiv2013

Effects of pressure on the ferromagnetic state of the CDW compound SmNiC2

We report the pressure response of charge-density-wave (CDW) and ferromagnetic (FM) phases of the rare-earth intermetallic SmNiC2 up to 5.5 GPa. The CDW transition temperature (T_{CDW}), which is reflected as a sharp inflection in the electrical resistivity, is almost independent of pressure up to 2.18 GPa but is strongly enhanced at higher pressures, increasing from 155.7 K at 2.2 GPa to 279.3 K at 5.5 GPa. Commensurate with the sharp increase in T_{CDW}, the first-order FM phase transition, which decreases with applied pressure, bifurcates into the upper (T_{M1}) and lower (T_c) phase transitions and the lower transition changes its nature to second order above 2.18 GPa. Enhancement both in the residual resistivity and the Fermi-liquid T^2 coefficient A near 3.8 GPa suggests abundant magnetic quantum fluctuations that arise from the possible presence of a FM quantum critical point.

cond-mat.str-el↗

arXiv2009

On varieties of almost minimal degree I: Secant loci of rational normal scrolls

To complete the classification theory and the structure theory of varieties of almost minimal degree, that is of non-degenerate irreducible projective varieties whose degree exceeds the codimension by precisely 2, a natural approach is to investigate simple projections of varieties of minimal degree. Let $\tilde X \subset {\mathbb P}^{r+1}_K$ be a variety of minimal degree and of codimension at least 2, and consider $X_p = π_p (\tilde X) \subset {\mathbb P}^r_K$ where $p \in {\mathbb P}^{r+1}_K \backslash \tilde X$. By \cite{B-Sche}, it turns out that the cohomological and local properties of $X_p$ are governed by the secant locus $Σ_p (\tilde X)$ of $\tilde X$ with respect to $p$. Along these lines, the present paper is devoted to give a geometric description of the secant stratification of $\tilde X$, that is of the decomposition of ${\mathbb P}^{r+1}_K$ via the types of secant loci. We show that there are exactly six possibilities for the secant locus $Σ_p (\tilde X)$, and we precisely describe each stratum of the secant stratification of $\tilde X$, each of which turns out to be a quasi-projective variety. As an application, we obtain the classification of all non-normal Del Pezzo varieties by providing a complete list of pairs $(\tilde X, p)$ where $\tilde X \subset {\mathbb P}^{r+1}_K$ is a variety of minimal degree, $p$ is a closed point in $\mathbb P^{r+1}_K \setminus \tilde X$ and $X_p \subset {\mathbb P}^r _K$ is a Del Pezzo variety.

math.AG↗

arXiv2005

Entanglement generation in harmonic chains: tagging by squeezing

We address the problem of spring-like coupling between bosons in an open chain configuration where the counter-rotating terms are explicitly included. We show that fruitful insight can be gained by decomposing the time-evolution operator of this problem into a pattern of linear-optics elements. This allows us to provide a clear picture of the effects of the counter-rotating terms in the important problem of long-haul entanglement distribution. The analytic control over the variance matrix of the state of the bosonic register allows us to track the dynamics of the entanglement. This helps in designing a global addressing scheme, complemented by a proper initialization of the register, which quantitatively improves the entanglement between the extremal oscillators in the chain, thus providing a strategy for feasible long distance entanglement distribution.

quant-ph↗

arXiv2005

Nonclassicality of a photon-subtracted Gaussian field

Recently, a non-Gaussian field, which may be a useful basis for entanglement distillation and efficient quantum teleportation, has been experimentally produced by subtracting a photon from a squeezed Gaussian field. We investigate the nonclassicality of such the field using negativity in the Wigner function and the existence of positive well-defined $P$ function. We obtain the condition to see negativity in the Wigner function for the case including the mixed Gaussian incoming field, the threshold photodetection and the inefficient homodyne measurement. We show how similar the photon-subtracted state is to a superposition of coherent states.

quant-ph↗