Doctoral Dissertations
Date of Award
8-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Physics
Major Professor
Thomas Papenbrock
Committee Members
Thomas Papenbrock, Lucas Platter, George Siopsis, Lawrence Heilbronn
Abstract
Quantum computation and quantum information, hot topics with immense potential, are making exciting strides in nuclear physics. The computational complexity of nuclear physics problems often surpasses the capabilities of classical computers, but quantum computing offers a promising solution. My research delves into the application of quantum computation and quantum information in nuclear physics.
I am curious about how to approach nuclear physics problems on a quantum computer. This dissertation studies how to prepare quantum states with quantum algorithms, as state preparation is a crucial initial step in studying nuclear dynamics. Two different quantum algorithms are studied: (i) the time-dependent method, which utilizes unitary evolution operator $\exp(-i\gamma \hat{O})$ for a relatively short time to approximate the target operator $\hat{O}$, and (ii) the Linear Combination of Unitaries (LCU) algorithm, which exactly conducts the action of target operator. A toy model for $n(p,d)\gamma$ reaction is studied using both techniques and implemented on simulated and real quantum devices. The results show the practicalness of both algorithms and show the LCU-based method is efficient even with noisy quantum computers nowadays.
Entanglement is viewed as a resource for many quantum processes and is essential for computational speed-up in quantum algorithms. Entanglement measurement and inspection of physics systems are vital. One would expect entanglement entropy to hold an area law (or with logarithmic correction) in lattice systems with local interactions. It is interesting to study if nuclear many-body systems agree with this statement. This dissertation uses the coupled-cluster method to study entanglement entropies between hole space (contains single-particle states below the Fermi level) and particle space (complement to the former) of nuclear many-body systems. The analytical results show that entanglement entropies are proportional to particle number fluctuation and depletion number of hole space for sufficiently weak interactions, which indicates entanglement entropies in nuclear systems fulfill a volume law instead of an area law. These results are confirmed by computing entanglement entropies of the pairing model and neutron matter.
Recommended Citation
Gu, Chenyi, "Quantum Computing and Information for Nuclear Physics. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/10459