Hardware-efficient arbitrary-angle decomposition of the full chiral evolution

Develop a hardware-efficient quantum-circuit implementation of the full three-spin chiral evolution \(\exp(-i\theta\chi_n)\) for an arbitrary rotation angle \(\theta\), rather than only for the known special angle \(\theta=2\pi/3\).

Background

The paper implements the chiral spin-chain through a decomposition into local three-body Pauli terms and corresponding gate sequences. It notes that a direct hardware-efficient implementation of the full three-spin unitary generated by the scalar spin-chirality operator is unavailable for general rotation angles. A special decomposition exists for the rescaled chirality operator at the fixed angle $\theta=2\pi/3$, using two SWAP gates, but that special point is free fermionic and therefore does not realize the general interacting chiral dynamics needed for the scrambling protocol.

Resolving this problem would provide a more direct and potentially lower-overhead implementation of the parent chiral Floquet circuit, enabling more faithful studies of the interacting dynamics on quantum hardware.