Programming long-range interactions in analog quantum simulators

TL;DR

This paper presents a hybrid classical-quantum approach to program and optimize long-range interactions in analog quantum simulators, significantly improving state preparation fidelity for large many-body systems.

Contribution

It introduces a method combining classical pre-optimization and quantum re-optimization to enhance the programmability and fidelity of long-range interactions in analog quantum simulators.

Findings

Achieved orders-of-magnitude improvements in fidelity and energy estimation.

Successfully scaled state preparation techniques to systems with 100-1000 particles.

Enabled controlled studies of many-body thermalization with tunable interactions.

Abstract

Long-range interactions are the source of many equilibrium and out-of-equilibrium quantum many-body phenomena. Analog simulators based on ionic, atomic, superconducting, and molecular systems provide a natural platform to obtain these interactions using vibration- and photon-mediated processes. Recent experimental advances, such as their integration in multi-mode cavities and waveguides, or the use of Raman-assisted transitions, enable dynamical control over both the strength and the spatial range of these interactions, thereby rendering them programmable. Here, we develop a hybrid classical-quantum toolbox that exploits this tunability to enhance many-body state preparation in analog simulators beyond fixed-connectivity architectures. Our approach is based on classical pre-compilation in homogeneous small systems, whose optimized parameters are extrapolated iteratively to larger system sizes, and then refined on the quantum hardware using noise-aware hybrid re-optimization and error-mitigation techniques. We benchmark this strategy across several fermionic, spin-1/2, and spin-1 models, demonstrating orders-of-magnitude improvements in fidelity and energy estimation for system sizes ranging from 100 to 1000 particles. Finally, we show that the combination of such high-fidelity programmable state preparation techniques with tunable-range out-of-equilibrium dynamics enables controlled studies of many-body thermalization in regimes accessible to current experimental platforms. Our results establish programmable long-range interactions as a powerful resource for next-generation analog quantum simulators.