Determine detector photoemission response to the locally measured field

Determine whether photoemission probabilities for a finite-size, finite-response detector carried along a trajectory parallel to a harmonically oscillating point charge are governed directly by the detector's proper-time spectrum, whether bound and induction components of the finite-distance electromagnetic field can produce photoelectrons, how the photoelectric threshold should be formulated for an accelerated detector, and whether a semiclassical or fully quantized electromagnetic description is required.

Background

The paper derives the exact classical electromagnetic field measured by an ideal pointlike observer comoving transversely with an oscillating charge, including its proper-time spectrum. It explicitly notes that this local classical spectrum is not by itself a detector count-rate prediction because a physical detector requires a specified coupling, bandwidth, spatial extent, and memory.

The authors then formulate unresolved questions concerning whether the local proper-time spectrum controls photoemission, whether finite-distance bound and induction fields can trigger photoelectrons, how acceleration modifies the photoelectric threshold, and whether semiclassical matter coupled to a classical field is sufficient or quantum field correlations are necessary.

References

The thought experiment raises several questions that lie beyond the present work. Is the photoemission probability governed directly by the proper-time spectrum obtained in Sec.~\ref{sec:proper-time-spectra}? Can the bound and induction parts of the finite-distance field produce photoelectrons, and, if so, can such a response be operationally distinguished from absorption of asymptotic radiation? How should the photoelectric threshold be formulated for an accelerated detector with finite size and response time? Would a semiclassical description of quantum matter coupled to the classical local field be sufficient, or is a quantized electromagnetic field required? In quantum photodetection theory, such probabilities depend on a specified detector--field coupling and on field correlation functions, illustrating why the local classical spectrum alone is not a complete count-rate prediction .

— Electromagnetic Field of an Oscillating Point Charge Measured by a Transversely Comoving Observer  (2610.09445 - Canora et al., 7 Oct 2026) in Section 8.2, “A photoemission thought experiment and open questions”

Uniform proper acceleration poses an especially sharp version of this thought experiment. A charge and a transversely separated coaccelerating detector may both be stationary in Rindler coordinates, while inertial observers assign radiation to the accelerated charge. If an explicit detector model predicts photoemission for the bounded motion studied here, does it also predict a response for an eternally uniformly accelerated charge? Alternatively, can the Rindler horizon and the stationarity of the field in the accessible wedge prevent the coaccelerating detector from accessing the radiative part of the field ? Does the answer change when uniform acceleration is maintained for only a finite interval, so that no eternal acceleration horizon is present? The thought experiment applies to all these trajectories, but its outcome need not be independent of the acceleration history and causal structure.

— Electromagnetic Field of an Oscillating Point Charge Measured by a Transversely Comoving Observer  (2610.09445 - Canora et al., 7 Oct 2026) in Section 8.2, “A photoemission thought experiment and open questions”

A related question concerns energy accounting. If photoelectrons are produced, how should the absorbed energy be divided among radiative energy from the charge, reversible bound-field energy, and work performed by the external agents that maintain the prescribed motions of the source and detector? Answering this question requires an explicit detector model, backaction, and a global energy-balance analysis. We leave these issues open.

— Electromagnetic Field of an Oscillating Point Charge Measured by a Transversely Comoving Observer  (2610.09445 - Canora et al., 7 Oct 2026) in Section 8.2, “A photoemission thought experiment and open questions”