Experimental Demonstration of Largeness in Bipartite Entanglement Sudden Death

Quantum coherence is the most distinct feature of quantum mechanics. However, inevitable decoherence processes will finally destroy it and make the "Schrödinger's cat" invisible in our classical world. In this "quantum-to-classical transition", the so-called "largeness" plays a critical role. We experimentally study the largeness phenomena in the bipartite entanglement decay process through a depolarizing channel with two-photon entangled states generated from a spontaneous parametric down-conversion source. Our experiment demonstrates how the speed of entanglement decay and the time when "entanglement sudden death" happens depend on the size of the system exposed to the environment noise.