  The quantum eraser effect exemplifies the distinct properties of quantum
mechanics that challenge classical intuition and expose the wave-particle
duality of light. This effect has been extensively explored in various
experiments; most of these investigations use polarisation to distinguish which
path information, and less attention has been paid to the phase structure which
is related wavefront of photon. In this study, we introduce a theoretical
framework for quantum erasure that focusses on the phase structure and
demonstrate it experimentally. In this experiment, we employ a Mach-Zehnder
interferometer (MZI) where a first-order spiral phase plate (SPP) is integrated
into one of its arms. This setup applied orbital angular momentum (OAM) to the
photons and established predetermined which-way information. Consequently, the
photon demonstrates its particle characteristics, with absence of interference
at the MZI's output ports. Utilizing an additional SPP to erase the phase
structure from the output photon results in pronounced interference patterns,
observable in a post-measurement scenario. This result allows us to include the
structure information of the equiphase plane of the light field in quantum
erasure. The results challenge the traditional cause-effect relationship in
classical physics, given that the subsequent choice of the SPP adheres to a
space-like separation.
