Direct laser acceleration of electrons assisted by strong laser-driven azimuthal plasma magnetic fields.

A high-intensity laser beam propagating through a dense plasma drives a strong current that robustly sustains a strong quasistatic azimuthal magnetic field. The laser field efficiently accelerates electrons in such a field that confines the transverse motion and deflects the electrons in the forward direction. Its advantage is a threshold rather than resonant behavior, accelerating electrons to high energies for sufficiently strong laser-driven currents. We study the electron dynamics via a test-electron model, specifically deriving the corresponding critical current density. We confirm the model's predictions by numerical simulations, indicating energy gains two orders of magnitude higher than achievable without the magnetic field

Preprint arXiv: 2106.05044 Submitted on 9 Jun 2021

As is well-known in the context of topological insulators and superconductors, short-range-correlated fermionic pure Gaussian states with fundamental symmetries are systematically classified by the periodic table. We revisit this topic from a quantum-information-inspired operational perspective without referring to any Hamiltonians, and apply the formalism to bosonic Gaussian states as well as (both fermionic and bosonic) locality-preserving unitary Gaussian operations. We find that while bosonic Gaussian states are all trivial, there exist nontrivial bosonic Gaussian operations that cannot be continuously deformed into the identity under the locality and symmetry constraint. Moreover, we unveil unexpectedly complicated relations between fermionic Gaussian states and operations, pointing especially out that some of the former can be disentangled by the latter under the same symmetry constraint, while some cannot. In turn, we find that some topological operations are genuinely dynamical, in the sense that they cannot create any topological states from a trivial one, yet they are not connected to the identity. The notions of disentanglability and genuinely dynamical topology apply equally to generic interacting topological phases and quantum cellular automata

Study of quasi-distributed optical fiber methane sensors based on laser absorption spectrometry

The coal industry plays an important role in the economic development of China. With the increase of coal mining year by year, coal mine accidents caused by gas explosion also occur frequently, which poses a serious threat to the life safety of absenteeism and national property safety. Therefore, high-precision methane fiber sensor is of great significance to ensure coal mine safety. This paper mainly introduces two kinds of quasi-distributed gas optical fiber sensing systems based on laser absorption spectroscopy. The gas fiber optic sensor based on absorption spectrum has high measurement accuracy, fast response and long service life. One is quasi-distributed optical fiber sensing system based on spatial division multiplexing (SDM) technology and the other is quasi-distributed optical fiber sensing system based on optical time domain reflection and time division multiplexing(TDM) technology

Preprint arXiv: 2210.05389 Submitted on 11 Oct 2022

We consider free fermions living on lattices in arbitrary dimensions, wherehopping amplitudes follow a power-law decay with respect to the distance. Wefocus on the regime where this power is larger than the spatial dimension(i.e., where the single particle energies are guaranteed to be bounded) forwhich we provide a comprehensive series of fundamental constraints on theirequilibrium and nonequilibrium properties. First we derive a Lieb-Robinsonbound which is optimal in the spatial tail. This bound then implies aclustering property with essentially the same power law for the Green'sfunction, whenever its variable lies outside the energy spectrum. The widelybelieved (but yet unproven in this regime) clustering property for theground-state correlation function follows as a corollary among otherimplications. Finally, we discuss the impact of these results on topologicalphases in long-range free-fermion systems: they justify the equivalence betweenHamiltonian and state-based definitions and the extension of the short-rangephase classification to systems with decay power larger than the spatialdimension. Additionally, we argue that all the short-range topological phasesare unified whenever this power is allowed to be smaller