Integrated photonics is an essential technology for optical quantum computing. Universal, phasestable, reconfigurable multimode interferometers (quantum photonic processors) enable manipulation of photonic quantum states and are one of the main components of photonic quantum computers in various architectures. In this paper, we report the realization of the largest quantum photonic processor to date. The processor enables arbitrary unitary transformations on its 20 input modes with a fidelity of (F Haar = 97.4%, F Perm = 99.5%), an average optical loss of 2.9 dB/mode, and high-visibility quantum interference (V HOM = 98%). The processor is realized in Si 3 N 4 waveguides.

Integrated photonics is an essential technology for optical quantum computing. Universal, phase-stable, reconfigurable multimode interferometers (quantum photonic processors) enable manipulation of photonic quantum states and are one of the main components of photonic quantum computers in various architectures. In this paper, we report the realization of the largest quantum photonic processor to date. The processor enables arbitrary unitary transformations on its 20 input modes with an amplitude fidelity of FHaar=97.4% and FPerm=99.5% for Haar-random and permutation matrices, respectively, an optical loss of 2.9 dB averaged over all modes, and high-visibility quantum interference with VHOM=98%. The processor is realized in Si3N4 waveguides and is actively cooled by a Peltier element.

We report the realization of the largest reconfigurable quantum photonic processor enabling arbitrary unitary transformations on its 20 input & output modes with an average fibre-to-fibre loss of 2.9 dB/channel. High-fidelity operation and high-visibility quantum interference is demonstrated.

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We experimentally investigate the relation between thermodynamics and quantum mechanics by demonstrating equilibration of a quantum state towards a thermal state in an integrated quantum photonics platform.

In a quantum-photonic experiment with an integrated quantum photonics network, we observe a quantum state locally evolve towards a thermal state. By undoing the evolution with the inverse network, we recover the input pure state.

We report the realization of the largest reconfigurable quantum photonic processor enabling arbitrary unitary transformations on its 20 input & output modes with an average fibre-to-fibre loss of 2.9 dB/channel. High-fidelity operation and high-visibility quantum interference is demonstrated.

The unification of general relativity and quantum theory is one of the fascinating problems of modern physics. One leading solution is Loop Quantum Gravity (LQG). Simulating LQG may be important for providing predictions which can then be tested experimentally. However, such complex quantum simulations cannot run efficiently on classical computers, and quantum computers or simulators are needed. Here, we experimentally demonstrate quantum simulations of spinfoam amplitudes of LQG on an integrated photonics quantum processor. We simulate a basic transition of LQG and show that the derived spinfoam vertex amplitude falls within 4% error with respect to the theoretical prediction, despite experimental imperfections. We also discuss how to generalize the simulation for more complex transitions, in realistic experimental conditions, which will eventually lead to a quantum advantage demonstration as well as expand the toolbox to investigate LQG. I. INTRODUCTION.