CCSE Members of the Electrodynamics Development Team

Revathi Jambunathan

Weiqun Zhang

Andrew Myers

Ann Almgren

Andy Nonaka

Don Willcox

Cameron Yang

Jackie Yao

Accelerator Modeling with WarpX

WarpX is an accelerator modeling code for the exascale being developed as part of DOE's Exascale Computing Program. CCSE researchers contribute to the core AMReX-based infrastructure for WarpX, and the implementation of sophisticated mesh refinement algorithms. Ongoing work includes extension of WarpX to work efficiently on hybrid CPU/GPU platforms.

The official ECP project page is here. The WarpX project is also a member of the NERSC NESAP-for-ECP program.

The project is led by Jean-Luc Vay of LBL's Applied Physics and Accelerator Technologies Division.

More information about the WarpX software can be found at

Spin Dynamics

The trend of technology in recent years has been towards miniaturization and interconnection. Continuous scaling down of circuitry is pushing Moore's law in the semiconductor industry nearly to an end and has entailed novel materials and new techniques to generate nanoscale devices with desired performance. Such new materials and techniques usually involve multiple physical mechanisms. For instance, one of the thriving techniques is to use magnetic spins to control and manipulate electromagnetic (EM) signals in radio-frequency (RF) circuitry, with exceptional scalability and low power dissipation. The corporation of new mechanism also enables things like quantum computing. However, the state-of-the-art design of RF magnetic devices has been hindered mainly by the lack of effective modeling tool to tackle the interaction between oscillating magnetization and EM waves. This problem is primarily due to the inherent disparity in time and length scale between magnetic spin oscillations and EM waves. Hence, in order to fully understand the underlying physics and design the next-generation devices, a new multiphysics modeling approach is needed.

We are using new physical coupling in potential electronic devices. This includes modeling and characterization of miniaturized magnetic components in radio-frequency (RF) systems, specifically nonlinear dynamic magnetic spin oscillations interacting with EM waves. We are developing a unique numerical algorithm to predict the influence of magnetic spins on the performance of compact RF devices. The Development of this multi-physics software is under the framework of AMReX, with features of massively parallel computing and block-structured adaptive mesh refinement (AMR). Such modeling tools enable a unique ability to accurately model and design next-generation RF systems and components.

For more information, contact Jackie Yao.

Astrophysical Plasma

In a new project which builds on the wave propagation methodology used in accelerator modeling, we are extending the capabilities of WarpX to model pulsar magnetosphere and relativistic magnetic reconnection relevant to various astrophysical phenomena.

Even though relativistic magnetic reconnection has been widely studied in the literature, the key mechanisms that govern the transfer of energy from the magnetic field to kinetic energy of accelerated charged plasma species are not well understood. Modeling the Harris-sheet magnetic reconnection problem using the ab-initio particle-in-cell approach will allow for the study of microscale kinetic behavior and its effect on the macroscale acceleration, reconnection rate, and plasmoid instabilities.

Pulsar magnetospheres and magnetic reconnection have never been studied with an AMR code; using this capability for modeling Maxwell's equations requires special care at the coarse-fine grid interface. The use of AMR will greatly reduce the computational cost since the length-scale of the magnetic reconnection system increases by nearly two orders of magnitude away from the current-sheet. The disparity in length-scales in further amplified for the pulsar magnetosphere simulation, where the difference between the smallest length-scale and radius of the neutron star is six orders of magnitude for a realistics pulsar.

Traditionally, to reduce the computational cost of modeling pulsars, the magnetic field energy of the system has been scaled down such that the length-scale difference is artificially decreased to two-orders of magnitude. However, decreasing the magnetic field strength directly affects the important pair-production processes that affects the prediction of gamma ray emission and current-sheet dynamics.

The extended WarpX code, with dynamic mesh refinement to capture the evolving current sheet of the magnetosphere, will be used to study the effect of energy-scaling on the gamma-ray emission and Poynting flux predictions for a rotating oblique pulsar.

For more information, contact Revathi Jambunathan, Don Willcox, or Cameron Yang.

Classical Modeling of Quantum Chips

In an effort to aid in the design of better quantum chip prototypes, we are developing a new numerical modeling capability to predict both the interaction between qubits and photons (known as circuit quantum electrodynamics, or QED) and the cross-talk between qubits and in-air electromagnetic (EM) waves.

This requires implementation of new physical models to resolve the non-linear interactions between the EM field and the quantum response from the Josephson junction modeled using a hybrid classical-quantum approach. Additionally, to model the photon-qubit interaction, the Maxwell's equations will be implicitly coupled to the Schrodinger equation that quantifies the qubit response to the applied and self-consistent EM field.

With the use of adaptive mesh and adaptive algorithm approach for this complex electrodynamic material model with a complex embedded geomtry, we will be able to conduct a detailed numerical study on the loss mechanisms for a given quantum chip prototype.

For more information, contact Jackie Yao, Revathi Jambunathan, or Andy Nonaka.