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We present an easy way of observing superluminal group velocities using abirefringent optical fiber and other standard devices. In the theoreticalanalysis, we show that the optical properties of the setup can be describedusing the notion of "weak value". The experiment shows that the group velocitycan indeed exceed c in the fiber; and we report the first direct observation ofthe so-called "signal velocity", the speed at which information propagates andthat cannot exceed c.Comment: 5 pages, 5 figure

Direct Measurement of Superluminal Group Velocity and Signal Velocity in an Optical Fiber