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Ling Gan

Publications and source records attributed to Ling Gan.

3 recordsLinked to original sources

Microscopic origins of inertial magnetization dynamics

Ultrafast experiments have uncovered inertial magnetization dynamics in ferromagnets, but their microscopic origin remains elusive. Using a non-Markovian quantum master equation we show that inertial dynamics arise from coherent interactions with optical phonons in the lattice. The fast optical frequency explains the nutation observed on picosecond timescales and accounts for variations between experiments through substrate-dependent phonon damping. By establishing magnon{phonon coupling as the microscopic basis of inertial magnetization, our results open new pathways for tailoring ultrafast spin dynamics and controlling magnetic states at terahertz frequencies.

cond-mat.mtrl-sci

Precision calculation of $^3$He$(\alpha,\gamma)^7$Be for solar physics

We calculate the cross section for radiative capture $^3$He$(\alpha,\gamma)^7$Be at next-to-next-to-leading order (NNLO). At this order of perturbation, momentum dependent two-body currents make their first appearance. We provide a model-independent construction of these currents from gauge and Galilean invariance, where the general framework for constructing higher-order two-body currents in low-energy effective field theories becomes evident. The $^3$He$(\alpha,\gamma)^7$Be astrophysical S-factor $S_{34}(0)= 0.564^{+0.17}_{-0.015}$ keV b is obtained from a Bayesian analysis at NNLO, with an additional nominal theoretical uncertainty $\pm0.017$ keV b of 3%.

nucl-th

Elastic scattering on a quantum computer

Scattering probes the internal structure of quantum systems. We calculate the two-particle elastic scattering phase shift for a short-ranged interaction on a quantum computer. Short-ranged interactions with a large scattering length or shallow bound state describe a universality class that is of interest in atomic, condensed matter, nuclear, and particle physics. The phase shift is calculated by relating the ground state energy of the interacting particles in a harmonic trap. The relaxation method is used as the variational quantum eigensolver for the ground state calculation. Schmidt decomposition is used to reduce quantum circuits nominally requiring tens of qubits to 2-qubit circuits, thus reducing the noise in quantum measurements. Calculations in multi-particle systems with many-body interactions would benefit from this reduction of qubits in noisy quantum processors.

nucl-th