A group of researchers from the University of Washington, the University of Trento, the Advanced Quantum Testbed (AQT), and Lawrence Livermore National Laboratory presented a hybrid algorithm for the simulation of the (real-time) dynamics of quantum mechanical systems of particles in a study that was published in Physical Review A.
A depiction of the collision of two neutrons simulated on a quantum chip at the Advanced Quantum Testbed. Image Credit: Image courtesy of S. Quaglioni (adapted from the Lawrence Berkely National Laboratory Advanced Quantum Testbed website.
The interactions between protons and neutrons, two quantum mechanical particles, result in the nuclear processes that drive stars and create elements. One of the hardest unresolved issues in computational physics is explaining these processes. Even the most potent conventional computers cannot keep up with the resources needed to simulate the growing mass of the colliding nuclei.
The required calculations might be completed by quantum computers. However, they do not currently have as many dependable and durable quantum bits as needed. The possibilities of overcoming this challenge have been significantly accelerated by this study, which integrated conventional and quantum computers.
The Impact
The researchers successfully employed a hybrid computing technique to model the scattering of two neutrons. This opens the door to calculating nuclear reaction rates that are difficult or impossible to measure in a laboratory. These include reaction rates, which have implications for astrophysics and national security.
The hybrid approach will also help to simulate the characteristics of other quantum mechanical systems. For example, it might aid researchers in studying the scattering of electrons with quantized atomic vibrations known as phonons, which are responsible for superconductivity.
Summary
In this hybrid technique, the spatial coordinates of the particles evolve over time on a classical processor, while the spin variables evolve on quantum hardware. The researchers showed their hybrid approach by modeling the scattering of two neutrons at the AQT.
The demonstration confirmed the idea of the proposed co-processing strategy after incorporating error mitigation mechanisms to increase the algorithm’s accuracy and using theoretical and experimental methodologies to understand the loss of quantum coherence.
Despite the simplicity of the demonstration system studied in this study, the results indicate that an extension of the current hybrid method might provide a potential avenue for simulating quantum scattering experiments with a quantum computer.
The hybrid algorithm, which uses future quantum platforms with longer coherence durations and greater quantum gate fidelities, would allow for the robust computing of complicated nuclear processes vital for astrophysics and nuclear science technology applications.
Funding
Department of Energy (DOE) Office of Science, Offices of Nuclear Physics and Advanced Scientific Computing Research, the Laboratory Directed Research and Development program at Lawrence Livermore National Laboratory, the National Science Foundation Graduate Research Fellowship Program, the DOE National Nuclear Security Administration, Advanced Simulation and Computing program, and the InQubator for Quantum Simulation (IQuS) at the University of Washington funded the study.
Journal Reference:
Turro, F., et. al. (2024) Demonstration of a quantum-classical coprocessing protocol for simulating nuclear reactions. Physical Review A. doi:10.1103/physreva.108.032417.