Space-Division-Multiplexing Platform for a Delayed-Choice Experiment

Abstract: This master’s thesis explores a space-division-multiplexing (SDM) platform fora delayed-choice experiment. SDM is a multiplexing technique for optical datatransmission that employs spatial modes in a multi- or few-mode fiber to increasethe transmission capacity. The spatial modes can thus be used as separate channels. SDM have shown great potential for quantum information systems, making it intriguing to investigate its broad applications by examining its use in adelayed-choice experiment. The delayed-choice experiment was proposed by J.A.Wheeler in 1978 explored the particle- and wave-like behavior of quantum particles and observe if the particle knows in advance if it should propagate as a waveor a particle through the experimental platform. Hence, it was suggested thatthe experiment should be changed after the particle entered the experimentalplatform. The experiment has afterward been realized in many different constellations but previous wave-particle delayed-choice experiments have not beendemonstrated with SDM nor with an all in fiber platform. The research involved modeling and constructing a SDM fiber-optic platform,only utilizing commercially available fiber optical telecommunication components. The platform was constructed with photonic lanterns, used as spatial division multiplexer and demultiplexer, and a two-input fiber Sagnac Interferometer,as a removable beam splitter. The system was tested with classical light but without difficulties, the platform could move to the quantum domain for performingthe delayed-choice experiment with single photons on the platform. The thesis resulted in a SDM platform with good performance for future measurement of bothparticle- and wave-like behavior of photons in a delayed-choice experiment.