Quantum Simulation Achieves Two-Nucleon Solution Using Just 4 Qubits
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Understanding the forces that bind protons and neutrons together within atomic nuclei remains a fundamental challenge in physics, demanding increasingly sophisticated computational methods. Bhoomika Maheshwari, Paul Stevenson, and P. Van Isacker, working at the Grand Accélérateur National d’Ions Lourds and the University of Surrey, now present a significant advance in simulating these complex systems. Their research demonstrates a novel quantum simulation technique capable of determining the low-lying energy states of any nuclear system in a single computational step, bypassing the need for multiple calculations typically required to find excited states. This achievement, demonstrated on a system of two nucleons, establishes a powerful new approach for exploring nuclear structure and pairing phenomena, paving the way for investigations on increasingly complex nuclei using current and future quantum computers. The nuclear shell model presents a highly complex computational challenge, scaling exponentially with the number of nucleons. This work details a numerical simulation employing the subspace search variational quantum eigensolver (SSVQE) combined with an adaptive derivative-assembled pseudo-trotter (ADAPT) ansatz, to obtain the low-lying states of any nuclear system within a single optimization run. Researchers demonstrated this approach using a simplified system, two identical nucleons within the 0p3/2 orbital, mapped to four qubits representing single-particle states. A surface delta effective interaction, a standard simplification for modelling nuclear forces, was incorporated using the Jordan-Wigner transformation, allowing for comprehensive analysis of the system’s quantum properties and behaviour. The ADAPT-SSVQE algorithm efficiently explores the vast computational space and accurately determines the ground and excited states of the nuclear system.
Nuclear Structure Solved via Quantum Computation This study pioneers a novel approach to solving the nuclear shell model, a notoriously complex computational problem, by combining the subspace search variational quantum eigensolver (SSVQE) with an adaptive derivative-assembled pseudo-trotter (ADAPT) ansatz. This method enables the simultaneous determination of low-lying energy states for any nuclear system within a single optimization run, circumventing the exponential scaling challenges of traditional calculations. Researchers initially focused on a simplified system, two identical nucleons within the 0p3/2 orbital, mapped onto four qubits to represent single-particle states. To translate the nuclear physics problem into a form suitable for quantum computation, the team employed the Jordan-Wigner transformation, converting fermionic creation and annihilation operators into qubit operators. This transformation, crucial for representing the anti-symmetric nature of nuclear wavefunctions, involved a string of Z Pauli matrices ensuring correct anti-commutation between qubits. The resulting Hamiltonian, expressed as a sum of Pauli strings, could then be directly implemented and measured on a quantum computer. The researchers constructed a surface delta interaction, calculating two-body matrix elements using Clebsch-Gordan coefficients to define the strength of the interaction between nucleons. The ADAPT-SSVQE algorithm uniquely optimizes a weighted energy sum, leveraging a symmetry-preserving double-excitation ADAPT operator pool to simultaneously converge on the two lowest energy states within a specific angular momentum subspace. The accuracy of this method was rigorously benchmarked against exact diagonalization, confirming its potential for probing nuclear structure and pairing phenomena using current and near-future quantum devices. The Hilbert space dimension for this initial calculation was 6, representing the possible states of two protons in the chosen orbital, but the method is designed to scale to more complex systems with multiple nucleons and orbitals, potentially reaching significantly larger computational spaces.
Nuclear Shell Model Simulation via Quantum Computing This work presents a breakthrough in simulating the nuclear shell model, a notoriously complex problem in physics, by combining a novel quantum computing approach with advanced algorithms. Scientists achieved a method for obtaining the low-lying energy states of any nuclear system within a single optimization run, overcoming limitations of traditional computational methods.
The team implemented a subspace search variational quantum eigensolver (SSVQE) combined with an adaptive derivative-assembled pseudo-trotter (ADAPT) ansatz to achieve this result. The research focused on a simplified system of two nucleons within a single orbital, mapped onto four qubits, to demonstrate the method’s accuracy. By utilizing a symmetry-preserving double-excitation ADAPT operator pool, the algorithm simultaneously converges on the two lowest energy states within a given angular momentum subspace. Measurements confirm the method’s ability to accurately reproduce known energy levels, as verified by comparison with exact diagonalization calculations. This validation demonstrates the potential for probing nuclear structure and pairing phenomena using current and near-future quantum devices. The core of the breakthrough lies in the ADAPT-SSVQE algorithm, which iteratively builds the quantum circuit by selecting the most relevant operators from a predefined pool. This pool consists of double-excitation operators, ensuring that the calculations conserve angular momentum.
The team employed a weighted loss function, prioritizing the convergence of states to the lowest energy eigenstates. Calculations were performed on a system representing a 0p3/2 orbital, resulting in a Hilbert space dimension of 6, but the method is designed to scale to much larger systems exceeding dimensions of 10 10 , which are intractable for classical computers. The results demonstrate a significant advancement in the ability to model complex nuclear systems, paving the way for deeper understanding of nuclear structure and reactions.
Nuclear Shell Model Solved with Quantum Simulation This work demonstrates a scalable approach to solving the nuclear shell model, a notoriously complex problem in physics. Researchers successfully simulated the pairing interactions of two identical nucleons using a hybrid quantum-classical algorithm, achieving simultaneous convergence of both ground and excited states within a single computational run. The method combines a subspace search eigensolver with an adaptive derivative-assembled pseudo-trotter ansatz, effectively capturing the correlations inherent in the nuclear many-body Hamiltonian. The simulation, performed on a noise-free quantum simulator, mapped the nuclear system onto qubits and utilized a symmetry-preserving operator to evolve the initial quantum states. This allowed the team to accurately determine the energy levels of the system, validating the approach against established theoretical benchmarks. While the current simulation focused on a simplified two-nucleon system, preliminary results indicate the method’s potential for application to more complex scenarios involving larger numbers of nucleons and incorporating both protons and neutrons. This advancement offers a promising pathway towards a deeper understanding of nuclear structure and pairing phenomena, potentially enabling detailed investigations inaccessible through traditional computational methods. 👉 More information 🗞 Single-step Quantum Simulation of Two Nucleons 🧠 ArXiv: https://arxiv.org/abs/2512.12798 Tags: