arXiv subjects

Ho

Publications and source records attributed to Ho.

5 recordsLinked to original sources

arXiv2025

Ultrafast Faraday Rotation Probe of Chiral Phonon-Polaritons in LiNbO3

Time reversal symmetry breaking motion of chiral phonon-polaritons in LiNbO3 is probed via the ultrafast Faraday effect. By combining a pair of perpendicularly polarized THz pulses with the right relative delay, we create a chiral THz driving field to excite chiral phonon-polaritons. The chiral atomic motion combines with the inverse Faraday effect from the circularly polarized THz pump to induce a magnetic moment field in the nonmagnetic material, LiNbO3. We attempt to quantify the strength of the magnetic field with Faraday rotation probe measurements. The direction of the Faraday signal flips when the input THz pulse is changed from left- to right-circular polarization, and we estimate a strong induced magnetic field strength of ~11 Tesla based on the Faraday rotation.

cond-mat.mes-hall↗

arXiv2022

A new standard in high-field terahertz generation: the organic nonlinear optical crystal PNPA

We report the full characterization of a new organic nonlinear optical (NLO) crystal for intense THz generation: PNPA ((E)-4-((4-nitrobenzylidene)amino)-N-phenylaniline). We discuss crystal growth and structural characteristics. We present the wavelength dependence of THz generation, the thickness dependence of the THz spectrum for PNPA crystals, and measure the efficiency. PNPA enables intense THz generation that surpasses NLO crystals DAST and OH-1, which have been the standard in organic high-field THz generators for several years.

physics.optics↗

arXiv2021

Compact Molecular Gas Distribution in Quasar Host Galaxies

We use Atacama Large Millimeter/submillimeter Array CO(2-1) observations of six low-redshift Palomar-Green quasars to study the distribution and kinematics of the molecular gas of their host galaxies at kpc-scale resolution. While the molecular gas content, molecular gas fraction, and star formation rates are similar to those of nearby massive, star-forming galaxies, the quasar host galaxies possess exceptionally compact, disky molecular gas distributions with a median half-light radius of 1.8 kpc and molecular gas mass surface densities $\gtrsim 22$ $M_\odot$pc$^{-2}$. While the overall velocity field of the molecular gas is dominated by regular rotation out to large radii, with rotation velocity-to-velocity dispersion ratio $\gtrsim 9$, the nuclear region displays substantial kinematic complexity associated with small-scale substructure in the gas distribution. A tilted-ring analysis reveals that the kinematic and photometric position angles are misaligned on average by $\sim 34 \pm 26^\circ$, and provides evidence of kinematic twisting. These observations provide tantalizing clues to the detailed physical conditions of the circumnuclear environments of actively accreting supermassive black holes.

astro-ph.GA↗

arXiv2007

Constructing Bio-molecular Databases on a DNA-based Computer

Codd [Codd 1970] wrote the first paper in which the model of a relational database was proposed. Adleman [Adleman 1994] wrote the first paper in which DNA strands in a test tube were used to solve an instance of the Hamiltonian path problem. From [Adleman 1994], it is obviously indicated that for storing information in molecules of DNA allows for an information density of approximately 1 bit per cubic nm (nanometer) and a dramatic improvement over existing storage media such as video tape which store information at a density of approximately 1 bit per 1012 cubic nanometers. This paper demonstrates that biological operations can be applied to construct bio-molecular databases where data records in relational tables are encoded as DNA strands. In order to achieve the goal, DNA algorithms are proposed to perform eight operations of relational algebra (calculus) on bio-molecular relational databases, which include Cartesian product, union, set difference, selection, projection, intersection, join and division. Furthermore, this work presents clear evidence of the ability of molecular computing to perform data retrieval operations on bio-molecular relational databases.

cs.NE↗

arXiv1998

Zeroth Sound Modes of Dilute Fermi Gas with Arbitrary Spin

Motivated by the recent success of optical trapping of alkali bosons, we have studied the zeroth sound modes of dilute Fermi gases with arbitrary spin-f, which are spin-S excitations ($0\leq S\leq 2f$). The dispersion of the mode (S) depends on a single Landau parameter $F^{(S)}$, which is related to the scattering lengths of the system through a simple formula. Measurement of (even a subset of) these modes in finite magnetic fields will enable one to determine all the interaction parameters of the system.

cond-mat↗