Sébastien Malherbe | Searcharxiv

arXiv2026

Celestial Mellin Amplitudes II: Spin-1 and Spin-2 Exchange, and Beyond

We further develop celestial Mellin amplitudes arXiv:2412.11992 to capture the exchange of particles with spin. For massless external scalar fields, we derive closed-form celestial Mellin amplitudes for a spin-1 and spin-2 exchange---both massless and massive---and extract the associated OPE data in the direct-channel. For gauge-boson and graviton exchanges, we identify in the celestial OPE the spin-1 current and the spin-2 stress tensor, together with the boundary gauge boson and graviton. Perturbative time-ordered correlators involving spinning fields can be obtained from those of scalars through the action of differential operators on the external points. In Mellin space these actions become finite-difference (shift) operators in the Mellin variables, which we use to extend our results to arbitrary integer spin.

hep-th↗

arXiv2023

Perceval: A Software Platform for Discrete Variable Photonic Quantum Computing

We introduce Perceval, an open-source software platform for simulating and interfacing with discrete-variable photonic quantum computers, and describe its main features and components. Its Python front-end allows photonic circuits to be composed from basic photonic building blocks like photon sources, beam splitters, phase-shifters and detectors. A variety of computational back-ends are available and optimised for different use-cases. These use state-of-the-art simulation techniques covering both weak simulation, or sampling, and strong simulation. We give examples of Perceval in action by reproducing a variety of photonic experiments and simulating photonic implementations of a range of quantum algorithms, from Grover's and Shor's to examples of quantum machine learning. Perceval is intended to be a useful toolkit for experimentalists wishing to easily model, design, simulate, or optimise a discrete-variable photonic experiment, for theoreticians wishing to design algorithms and applications for discrete-variable photonic quantum computing platforms, and for application designers wishing to evaluate algorithms on available state-of-the-art photonic quantum computers.

quant-ph↗