Models of quantum gravity imply a modification of the canonical position-momentum commutation relations. In this manuscript, working with a binary mechanical system, we examine the effect of quantum gravity on the exceptional points of the system. On the one side, we find that the exceedingly weak effect of quantum gravity can be sensed via pushing the system towards a second-order exceptional point, where the spectra of the non-Hermitian system exhibits non-analytic and even discontinuous behavior. On the other side, the gravity perturbation will affect the sensitivity of the system to deposition mass. In order to further enhance the sensitivity of the system to quantum gravity, we extend the system to the other one which has a third-order exceptional point. Our work provides a feasible way to use exceptional points as a new tool to explore the effect of quantum gravity.

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Quantum correlation of two-photon states is utilized to suppress the environmental noise in imaging down to the single-photon level. However, the size of the coherence area of the photon pairs limits the applications of quantum imaging based on spatial correlations. Here, a quantum imaging scheme exploiting twisted photon pairs with tunable spatial-correlation regions to circumvent this limitation is proposed. A bulk-density coincidence is employed to enhance the imaging signal. Specifically, a re-scaled image signal is introduced, which is immune to the background intensity distribution profile of the photon pulse. A destructive interference between the anti-bunched photon pair and bunched photon pair in the imaging process is revealed. This work can pave a way for twisted-photon-based quantum holography and quantum microscopy.

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