Quantum coherence is now observed in a variety of physical systems and is the key underlying concept in modern quantum physics. In experiment, quantum coherence is often manifested in various forms of quantum superposition, interference, and entanglement, all of which are essential for quantum information processing. While certain man-made physical systems may now show limited quantum coherence, photons and atoms are the most ideal physical systems for investigating various manifestations of quantum coherence as they are free of defects. In this talk, I will first give basic terminology definitions and present how starkly quantum physics differs from classical physics with a counter-intuitive example involving the simplest quantum system, a quantum bit . I will then review some of my group’s recent work on quantum coherence carried out with entangled photons and cold atoms, including quantum-to-classical transition [2,3], quantum walk , dynamic beam splitting with atoms , and generating Einstein-Podolsky-Rosen entanglement using cold atoms . I will also discuss how these lines of research may someday enable large-scale quantum information processors.
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