Quantum Computing Unlocks New Approach to Study Energy Levels of 58 Ni: A Nuclear Physics Breakthrough

Researchers Bharti Bhoy and Paul Stevenson from the University of Surrey have used a simulated quantum computing approach to investigate the shell model energy levels 58Ni, an isotope of interest in nuclear physics and astrophysics. Using the variational eigensolver (VQE) method and a problem-specific ansatz, they could reproduce exact energy values for the ground state and first and second excited states. The study represents a significant step in applying quantum computation to the study of atomic nuclei, potentially revolutionizing the field. The researchers’ method was validated by the exact agreement between classical and qubit-mapped diagonalization.

What is the Quantum Computing Approach to the Shell Model Study of 58Ni?

The study presents a simulated quantum computing approach for the investigation into the shell model energy levels of 58Ni. The primary objective is to achieve a fully accurate low-lying energy spectrum of 58Ni. The chosen isotope, 58Ni, is particularly interesting in nuclear physics due to its role in astrophysical reactions. It is also a simple but non-trivial nucleus for shell model study, being two particles outside a closed shell.

The researchers, Bharti Bhoy and Paul Stevenson from the Department of Physics at the University of Surrey, used the variational eigensolver (VQE) method combined with a problem-specific ansatz. The ansatz, along with the VQE method, was shown to be able to reproduce exact energy values for the ground state and first and second excited states. The researchers compared a classical shell model code, the values obtained by diagonalization of the Hamiltonian after qubit mapping, and a noiseless simulated ansatz-VQE simulation. The exact agreement between classical and qubit-mapped diagonalization showed the correctness of their method and the high accuracy of the simulation.

How Does Quantum Computation Apply to Atomic Nuclei?

Atomic nuclei are systems of interacting spin-1/2 fermions. Their simulation is a strong candidate for a possibly revolutionary treatment using quantum computation. A standard microscopic method to interpret observed states of nuclei is the configuration interaction nuclear shell model. In this model, nucleons interact in a defined single-particle basis to produce correlated eigenstates of a model Hamiltonian.

The researchers explored a heavier system than previously explored, looking at a nucleus 58Ni with valence particles in the fp-shell. They used a simulated variational quantum eigensolver (VQE) algorithm to compare aspects of the method in comparison with an exact classical shell model calculation. The choice of 58Ni was primarily motivated as being the simplest two-valence-particle system in the fp-shell and one with which they could compare their quantum simulation calculations with classical shell model.

What is the Significance of 58 Ni in Astrophysics?

The isotope 58Ni is particularly interesting in astrophysics in the s-process in AGB stars. It is a well-studied nuclear for use as a nuclear data benchmark and as a nuclear material. The primary objective of the research was to achieve a high level of precision in determining the low-lying energy levels of 58Ni by constructing a problem-based ansatz able to reproduce exact results based on the shell-model interaction JUN45.

What is the Theoretical Framework of the Study?

In the study, the researchers investigated the properties of the 58Ni nucleus using quantum computing simulation techniques along with a classical shell model comparison. They took the model space comprising orbitals 1 p3/2, 0f5/2, and 1 p1/2 above the 56Ni core. The Hamiltonian employed was adapted for quantum computing simulation. They presented the tailored ansatz as appropriate to reach the ground state of the system.

The researchers discussed the application of the Variational Quantum Eigensolver (VQE) algorithm and associated optimizers for energy minimization. Implementing excitation operators, crucial for constructing quantum circuits, was detailed. The shell model Hamiltonian was expressed regarding second quantization, where creation and annihilation operators act on states representing single-particle wavefunctions.