Facility for Rare Isotope Beams

Committee: Ryan Ringle (Chairperson), Kei Minamisono, Scott Pratt, Reinhard Schwienhorst, Hui-Chia Yu.

*Please note that this seminar will take place at 10am Eastern Time Neutron Stars are born in core-collapse supernovae being the endpoint of stellar evolution of massive stars. Their extreme properties allow for the study of dense matter in the sky. In recent years the advancement of astrophysical observations has been so tremendous that the properties of neutron stars can be constrained nowadays to an unprecedented level. I will summarize the basic observations of neutron star masses from pulsar data, the constraints on radii from x-ray measurements, and the first detection of gravitational waves from a neutron star merger. On the other hand, I will discuss the nuclear and particle physics aspects of the equation of state of neutron star matter which is firmly limited at low and high energy densities. Chiral effective field theory puts a stringent constraint up to about saturation density for pure neutron matter. Perturbative QCD calculations narrow the equation of state at ultimately high densities. Finally, I will address the possible existence of new phases in the core of neutron stars which can be revealed from the mass-radius relation of neutron stars. I will argue that it is in principle impossible to rule out phase transitions in neutron stars from observations based on general relativity alone. Speaker Homepage: https://astro.uni-frankfurt.de/schaffner/

Quantum computers offer the potential to simulate nuclear processes that are classically intractable. With the goal of understanding the necessary quantum resources, we employ state-of-the-art Hamiltonian-simulation methods, and conduct a thorough algorithmic analysis, to estimate the qubit and gate costs to simulate low-energy effective field theories (EFTs) of nuclear physics. In particular, within the framework of nuclear lattice EFT, we obtain simulation costs for the leading-order pionless and pionful EFTs. We consider both static pions represented by a one-pion-exchange potential between the nucleons, and dynamical pions represented by relativistic bosonic fields coupled to non-relativistic nucleons. We examine the resource costs for the tasks of time evolution and energy estimation for physically relevant scales. We account for model errors associated with truncating either long-range interactions in the one-pion-exchange EFT or the pionic Hilbert space in the dynamical-pion EFT, and for algorithmic errors associated with product-formula approximations and quantum phase estimation. Our results show that the pionless EFT is the least costly to simulate and the dynamical-pion theory is the costliest. We demonstrate how symmetries of the low-energy nuclear Hamiltonians can be utilized to obtain tighter error bounds on the simulation algorithm. By retaining the locality of nucleonic interactions when mapped to qubits, we achieve reduced circuit depth and substantial parallelization. This work highlights the importance of combining physics insights and algorithmic advancement in reducing quantum-simulation costs.

The STREAMLINE (SmarT Reduction and Emulation Applying Machine Learning In Nuclear Environments) collaboration aims to advance the frontiers of theoretical and computational research on the nuclear many-body problem using ML. The scientific problems we address are among the most challenging in computational nuclear many-body theory and the collaboration is aligned with the U.S. government initiative to build a broad-based, multidisciplinary, multi-agency program for a sustained national AI structure. STREAMLINE will advance large nuclear physics computations to dramatically increase predictive power and improve our understanding of nuclear structure and dynamics, dense nucleonic matter, and emergent many-body phenomena -- this includes the properties of heavy neutron-rich nuclei and related astrophysical environments at the Facility for Rare Isotope Beams (FRIB); structure and reactions of nuclei and nuclear astrophysics at the Argonne Tandem Linac Accelerator System (ATLAS); neutron distributions in nuclei and few-body systems at Thomas Jefferson National Accelerator Facility (TJNAF); properties of fission at Los Alamos Neutron Science Center (LANSCE); and nuclear structure, reactions, and astrophysics at Association for Research at University Nuclear Accelerator facilities (ARUNA).

The Nuclear Science Summer School (NS3) is a summer school that introduces undergraduate student participants to the fields of nuclear science and nuclear astrophysics. NS3 is hosted by FRIB on the campus of Michigan State University (MSU). The school will offer lectures and activities covering selected nuclear science and astrophysics topics.