RESUMEN
Two-photon Hong-Ou-Mandel (HOM) interference is a fundamental quantum effect with no classical counterpart. The existing research on two-photon interference was mainly limited in one degree of freedom (DOF); hence, it is still a challenge to realize quantum interference in multiple DOFs. Here, we demonstrate HOM interference between two hyperentangled photons in two DOFs of polarization and orbital angular momentum (OAM) for all 16 hyperentangled Bell states. We observe hyperentangled two-photon interference with a bunching effect for ten symmetric states (nine boson-boson states and one fermion-fermion state) and an antibunching effect for six antisymmetric states (three boson-fermion states and three fermion-boson states). More interestingly, expanding the Hilbert space by introducing an extra DOF for two photons enables one to transfer the unmeasurable external phase in the initial DOF to a measurable internal phase in the expanded two DOFs. We directly measured the symmetric exchange phases being 0.012±0.002, 0.025±0.002, and 0.027±0.002 in radian for the three boson states in OAM and the antisymmetric exchange phase being 0.991π±0.002 in radian for the other fermion state, as theoretical predictions. Our Letter may not only pave the way for more wide applications of quantum interference, but also develop new technologies by expanding Hilbert space in more DOFs.
RESUMEN
BACKGROUND: Food protein-induced enterocolitis syndrome (FPIES) is a delayed, non-IgE-mediated food allergy. This syndrome was once thought to be rare, but emerging literature suggests an increasing incidence along with more foods being implicated. Also, with the introduction of guidelines on early peanut introduction, peanut-induced FPIES seems to be increasing in Australia and USA. Although most patients are diagnosed with FPIES within the first year of life, most commonly with food triggers to cow's milk or soy, other phenotypes exist in comparison to this classic presentation. In this case report, we present a patient with late onset of acute FPIES at age 3 to walnut. CASE PRESENTATION: We describe a case of FPIES in a 12-year-old boy who had recurrent episodes of repetitive emesis, that began at age 3, each time after consuming walnuts. Mom does not give a history of intentional feeding (or avoidance) of walnut and/ or pecans. She also described possible reactions with pine nuts and macadamia. He was assessed with an oral food challenge to walnut, which triggered an episode of acute FPIES. He developed vomiting with onset 2 h post-ingestion, pallor, lethargy, and required an emergency department visit for anti-emetic medications and oral rehydration therapy. He improved on the therapy and now avoids cashew, pistachio, hazelnuts, walnuts, pecans, pine nuts, and macadamia nuts. CONCLUSIONS: This case report adds to the limited literature that exists on culprit food allergens in FPIES. We present an acute FPIES triggered by the ingestion of walnuts. The diagnosis, common food triggers, and natural history of FPIES are described. There remains a lack of information on the natural history of FPIES, especially towards uncommon food triggers and on FPIES that present beyond infancy.