Whether a quantum many-body system can be efficiently simulated hinges not only on its size but also on how quantum resources are organized within it. We characterize the quantum resource landscape of collective neutrino oscillations using entanglement entropy, non-local magic, and matrix product state bond dimension. Using tensor network simulations of neutrinos in the two-flavor sector, we demonstrate that spectral splits--sharp energy-dependent flavor swaps--emerge precisely where entanglement entropy is maximized and non-local magic is minimized locally. This anticorrelation reveals that spectral splits arise not from generic resource growth but from a structured redistribution among flavor modes. The resource dynamics trace constrained arcs in the entanglement-magic phase space, bounded by entanglement spectrum normalization. These findings establish a direct, quantitative link between quantum resources governing computational complexity and astrophysical observables, informing the design of tensor network and quantum circuit simulations of dense neutrino environments.
Whether a quantum many-body system can be efficiently simulated hinges not only on its size but also on how quantum resources are organized within it. We characterize the quantum resource landscape of collective neutrino oscillations using entanglement entropy, non-local magic, and matrix product state bond dimension. Using tensor network simulations of neutrinos in the two-flavor sector, we demonstrate that spectral splits--sharp energy-dependent flavor swaps--emerge precisely where entanglement entropy is maximized and non-local magic is minimized locally. This anticorrelation reveals that spectral splits arise not from generic resource growth but from a structured redistribution among flavor modes. The resource dynamics trace constrained arcs in the entanglement-magic phase space, bounded by entanglement spectrum normalization. These findings establish a direct, quantitative link between quantum resources governing computational complexity and astrophysical observables, informing the design of tensor network and quantum circuit simulations of dense neutrino environments.
Collective neutrino oscillations play a crucial role in transporting lepton flavor in astrophysical settings, such as supernovae, where the neutrino density is large. In this regime, neutrino-neutrino interactions are important and simulations in the mean-field approximation show evidence for collective oscillations occurring at timescales much shorter than those associated with vacuum oscillations. In this work, we study the out-of-equilibrium dynamics of a corresponding spin model using matrix product states and show how collective bipolar oscillations can be triggered by many-body correlations if appropriate initial conditions are present. We find entanglement entropies scaling at most logarithmically in the system size suggesting that classical tensor network methods could be efficient in describing collective neutrino dynamics more generally. These observation provide a clear path forward, not only to increase the accuracy of current simulations, but also to elucidate the mechanism behind collective flavor oscillations without resorting to the mean-field approximation.
In environments such as core-collapse supernovae, neutron star mergers, or the early universe, where the neutrino fluxes can be extremely high, neutrino-neutrino interactions are appreciable and contribute substantially to their flavor evolution. Such a system of interacting neutrinos can be regarded as a quantum many-body system, and prospects for nontrivial quantum correlations, i.e., entanglement, developing in a gas of interacting neutrinos have been investigated previously. In this work, we uncover an intriguing connection between the entropy of entanglement of individual neutrinos with the rest of the ensemble, and the occurrence of spectral splits in the energy spectra of these neutrinos, which develop as a result of collective neutrino oscillations. In particular, for various types of neutrino spectra, we demonstrate that the entanglement entropy is highest for the neutrinos whose locations in the energy spectrum are closest to the spectral split(s). This trend demonstrates that the quantum entanglement is strongest among the neutrinos that are close to these splits, a behavior that seems to persist even as the size of the many-body system is increased.
We consider the quantum magic in systems of dense neutrinos undergoing coherent flavor transformations, relevant for supernova and neutron-star binary mergers. Mapping the three-flavor-neutrino system to qutrits, the evolution of quantum magic is explored in the single scattering angle limit for a selection of initial tensor-product pure states for N ν ≤ 8 neutrinos. For | ν e 〉 ⊗ N ν initial states, the magic, as measured by the α = 2 stabilizer Renyi entropy M 2 , is found to decrease with radial distance from the neutrino sphere, reaching a value that lies below the maximum for tensor-product qutrit states. Further, the asymptotic magic per neutrino, M 2 / N ν , decreases with increasing N ν . In contrast, the magic evolving from states containing all three flavors reaches values only possible with entanglement, with the asymptotic M 2 / N ν increasing with N ν . These results highlight the connection between the complexity in simulating quantum physical systems and the parameters of the Standard Model.
We consider the quantum magic in systems of dense neutrinos undergoing coherent flavor transformations, relevant for supernova and neutron-star binary mergers. Mapping the three-flavor-neutrino system to qutrits, the evolution of quantum magic is explored in the single scattering angle limit for a selection of initial tensor-product pure states for Nν≤8 neutrinos. For ∣νe⟩⊗Nν initial states, the magic, as measured by the α=2 stabilizer Renyi entropy M2, is found to decrease with radial distance from the neutrino sphere, reaching a value that lies below the maximum for tensor-product qutrit states. Further, the asymptotic magic per neutrino, M2/Nν, decreases with increasing Nν. In contrast, the magic evolving from states containing all three flavors reaches values only possible with entanglement, with the asymptotic M2/Nν increasing with Nν. These results highlight the connection between the complexity in simulating quantum physical systems and the parameters of the Standard Model.
Neutrino evolution in dense astrophysical environments is typically described either within a quantum kinetic framework, which neglects the build-up of multi-body correlations, or through simplified many-body calculations that allow significant entanglement to develop. In this work, we compare these two approaches in a simple neutrino-gas configuration, with particular emphasis on the role of non-forward scattering processes. These effects are incorporated either through a collision term in the kinetic description, or by considering the full neutrino-neutrino many-body Hamiltonian. We highlight differences between the two descriptions in both their characteristic timescales and asymptotic behavior. Motivated by the natural suitability of quantum computing for many-body calculations, we further investigate the non-classicality of neutrino evolution, discussing Trotter error scaling, along with the associated costs of constructing quantum circuits in terms of entangling gates and non-Clifford gates. We find that the resources needed for neutrino many-body evolution are on the low end of typical high-energy physics problems and on the mid to high end with respect to quantum chemistry problems. For the full Hamiltonian, resource requirements increase relative to the truncated version. We emphasize the importance of efficient fermion-to-qubit encodings, which are essential for reducing the substantial computational resources required for such simulations.
We explore the utility of qutrits and qubits for simulating the flavor dynamics of dense neutrino systems. The evolution of such systems impacts some important astrophysical processes, such as core-collapse supernovae and the nucleosynthesis of heavy nuclei. Many-body simulations require classical resources beyond current computing capabilities for physically relevant system sizes. Quantum computers are therefore a promising candidate to efficiently simulate the many-body dynamics of collective neutrino oscillations. Previous quantum simulation efforts have primarily focused on properties of the two-flavor approximation due to their direct mapping to qubits. Here, we present new quantum circuits for simulating three-flavor neutrino systems on qutrit- and qubit-based platforms, and demonstrate their feasibility by simulating systems of two, four, and eight neutrinos on IBM and Quantinuum quantum computers.