Final Report Summary - MOQUASIMS (Memory-enabled Optical Quantum Simulators) The project “Memory-enabled Optical Quantum Simulators (MOQuaSims)” aims to construct and implement the first memory-enabled optical quantum simulator and use it to perform the next generation of quantum simulations. This is compose of three distinct and ambitious objectives: building a broadband quantum memory and observing interference between flying photons and stationary atomic excitations; simulating photosynthetic complex in a simplified model by means of an all-optical quantum network; realizing a dynamically programmable memory-enabled optical quantum simulator. To approach those objectives, we have made achievements in following three aspects. We have designed and built a quantum memory setup that can store broadband light in room-temperature caesium vapour, and we have identified an unwanted four wave mixing process in far off-resonance regime as a key noise source and developed noise-free quantum memory in a ring cavity; We have successfully built an all-optical quantum network on a photonic chip reaching a very high complexity, including two photonic pairs, three coupled interferometers, eight spatial modes and many non-classical interferences, and performed quantum simulation experiments on such all-optical quantum network; We have gathered all key techniques for dynamically programmable memory-enabled optical quantum simulator, including dynamically programmable light storage, noise-free quantum memory and quantum simulator based on all-optical network, and we have been proceeding towards the final integration.The expected final results have also been delivered in three aspects. Firstly, the quantum memory we developed has many unique features, with which GHz broadband flying photons can be stored into stationary atomic excitations and retrieved in any programmable way and in very low noise level, single photon can therefore be transported with sub-nanosecond period. Secondly, quantum simulator we developed in all-optical integrated network has already been a powerful platform which can simulate novel physics in very wide spectrum, for example genuine multi-photon interference on very complex system, Boson sampling in very large scale comparing with simple two photon HOM interference and quantum random walk which is analogue to photosynthetic complex. Thirdly, the final integration to be achieved will enable more versatile and powerful quantum simulation with which the dynamics between sites can be tuned in a programmable fashion, and may also provide the capacity to look into novel and interesting physics potentially. Our results will shed new light on investigation on energy transportation in photosynthesis system and may inspire engineer on designing high-efficiency artificial photovoltaic device which is currently main way pursued by mankind for green energy. Besides the impact to the field of quantum simulation, the techniques we have developed may find many applications in the filed of quantum communication, quantum computation and quantum metrology. For example, the high-speed light storage can be used to synchronize probabilistic single photon source to large-scale multiphoton source, and can be used as key elements in quantum repeater which enable unconditional secure communication in long distance. The all-optical integrated network may also find application for demonstrating new quantum algorithms associated with quantum random walk beyond the capacity of classical computers. The capacity to generate on-chip photon source and on-chip manipulation may enable quantum-enhanced precise measurement with a sensitivity beyond standard quantum limit. Our results therefore may also provide possibilities to find applications in many other quantum-enhanced technologies which possess the capacities to revolutionize our life in many specific areas, including unconditional secure communication, super fast computation and super precise measurement.
