Harnessing time symmetry to fundamentally alter entanglement in photoionization

The Grobe-Eberly doublet phenomenon occurs in photoelectron distributions when a field dresses the remaining ion. Its manifestation is due to entanglement between a free electron and a hybrid state of light and matter. Direct detection of such entanglement is however not possible by coincidence schemes due to the dressing mechanism having an inconspicuous phase-correlation effect on the ion. Here, it is shown that odd envelopes fundamentally alter the entanglement, such that channel-resolved photoelectron distributions become identifiable in coincidence with the internal state of the field-free ion. This constitutes a first usage of the parity of time symmetry in strong-field interactions.