Entanglement

In this article we establish new bounds on the quantum communication complexity of distributed problems. Specifically, we consider the amount of communication that is required to transform a bipartite state into another, typically more entangled, state. We obtain lower bounds in this setting by studying the Renyi entropy of the marginal density matrices of the distributed system.The communication bounds on quantum state transformations also imply lower bounds for the model of communication complexity where the task consists of the the distributed evaluation of a function f(x,y). Our approach encapsulates several known lower bound methods that use the log-rank or the von Neumann entropy of the density matrices involved. The technique is also effective for proving lower bounds on problems involving a promise or for which the "hard" distributions of inputs are correlated. As examples, we show how to prove a nearly tight bound on the bounded-error quantum communication complexity of the ...

Optical Components for Quantum EntanglementAn optical-based quantum information processing system utilizes entangled photons to transmit, encode, and process enormous amount of data. Such entangle photons can be generated by spontaneous parametric down conversion (SPDC) in second-order nonlinear optical crystals. Newlight Photonics Inc. has developed a series of optical components for generation, measurement, and manipulation of entangled photons.