In the noisy intermediate-scale quantum era, variational algorithms have become a standard approach to solving quantum many-body problems. Here, we present variational quantum eigensolver results of selected oxygen isotopes within the shell-model description. The aim of the present work is to locate the neutron drip line of the oxygen chain using unitary coupled cluster type Ansätze with different microscopic interactions (DJ16, JISP16, and N3LO), in addition to a phenomenological USDB interaction. While initially infeasible to execute on contemporary quantum hardware, the size of the problem is reduced significantly using qubit tapering techniques in conjunction with custom circuit design and optimization. The optimal values of Ansatz parameters from classical simulation are taken for the DJ16 interaction, and the tapered circuits are run on IonQ's Aria, a trapped-ion quantum computer. After applying gate error mitigation for three isotopes, we reproduced exact ground-state energies within a few percent error. The postprocessed results from hardware also clearly show ${}^{24}\mathrm{O}$ as the drip line nucleus of the oxygen chain. Future improvements in quantum hardware could make it possible to locate drip lines of heavier nuclei.

We report ab initio no-core shell-model (NCSM) study of ¹⁸⁻²⁴Ne isotopes for energy spectra, electromagnetic properties, and point-proton radii using three realistic NN interactions. We have used inside nonlocal outside Yukawa (INOY), charge-dependent Bonn 2000 (CDB2K) and the chiral next-to-next-to-next-to-leading order (N³LO) interactions. We are able to reach basis size up to N _max = 6 for ¹⁸Ne and N _max = 4 for the ¹⁹⁻²⁴Ne isotopes with m-scheme dimensions up to 1.0 × 10⁹ in case of ²⁴Ne. We observed better results for INOY interaction in terms of the binding energies of the ground state, and overall all three interactions provide good agreement with the experimental low-energy spectra. Our results for reduced M1 transition strengths and magnetic moments are close to the experimental values. We found that for long-range observables such as the E2 transition strengths, the electric quadrupole moments, and the point-proton radii (r _p ), we need higher N _max calculations to obtain results comparable to the experimental data. We have observed almost 6% increment in the converged r _p as we increase the model space from N _max = 4 to N _max = 6.

In this paper, the importance of isospin symmetry and its breaking in elucidating the properties of atomic nuclei is reviewed. The quark mass splitting and the electromagnetic origin of the isospin symmetry breaking (ISB) for the nuclear many-body problem is discussed. The experimental data on isobaric analogue states cannot be described only with the Coulomb interaction, and ISB terms in the nucleon–nucleon interaction are needed to discern the observed properties. In the present work, the ISB terms are explicitly considered in nuclear energy density functional and spherical shell model approaches, and a detailed investigation of the analogue states and other properties of nuclei is performed. It is observed that isospin mixing is largest for the N = Z system in the density functional approach

The observation of active ^{44}Ti in supernova remnants offers the potential to solve one of the most debated questions in modern astrophysics, the exact underlying explosion mechanism of core collapse supernovae (CCSNe). In particular, a comparison between the predicted synthesized yield of ^{44}Ti and the ejected flux is expected to allow for a determination of the mass cut of the star. Unfortunately, such comparisons are currently severely hindered by large uncertainties in the nuclear reactions governing the production and destruction of ^{44}Ti. On this note, the astrophysical ^{45}V(p,γ)^{46}Cr reaction is expected to play a decisive role. We present the first experimental information on resonant states in the ^{45}V(p,γ)^{46}Cr reaction. Excitation energies have been measured with high precision for ten previously unknown, low-spin, proton-unbound states in ^{46}Cr, and spin-parity-assignment constraints have been made using observed γ-decay patterns and shell-model calculations. We find that an ℓ=1 resonance at 714 keV dominates the ^{45}V(p,γ)^{46}Cr reaction for the entire temperature range of α-rich freezeout. Moreover, the nominal rate is found to be ∼25-50% of previous estimates for T>1.2 GK, indicating an increase in ^{44}Ti production in CCSNe of ∼20-35%.