Slow Light Easy To Create

University of Rochester researchers have developed a small device to create slow light — at 127 miles per hour more than 5 million times slower than the normal speed of light. They say it could pave the way for slow light to move from a physical curiosity to a useful telecommunications tool. Researchers used a laser to “punch a hole” in the absorption spectrum of a ruby. To slow light the team used a quantum quirk called “coherent population oscillations” to create a gap in the frequencies of light a ruby absorbs. When the second beam, called the probe laser, shines into the ruby the probe beam has a different frequency than the first laser, and these offset frequencies interact, causing variations. Chromium ions respond to this new frequency of rhythmic highs and lows by oscillating in sympathy, which allows the probe laser to pass through the ruby more slowly than light otherwise would travel.