Scientists Build Laser the Size of a Grain of Rice

Posted on January 17, 2015

Scientists at Princeton University have built a laser the size of a grain of rice. The tiny laser is powered one electron at a time and gives off microwaves that build into a coherent beam of light. The single atoms tunnel through artificial atoms called quantum dots in the tiny microwave laser, which is also known as a maser.

The researchers built the tiny laser as they were exploring how to use quantum dots. The initial goal was to explore the use of double quantum dots but they ended up creating a laser instead. They say it requires about one-billionth the electric current needed to power a hair dryer.

Jason Petta, an associate professor of physics at Princeton who led the study, says in a statement, "It is basically as small as you can go with these single-electron devices."

Petta also explained how each double quantum dot can transfer just one electron at a time. He says, "It is like a line of people crossing a wide stream by leaping onto a rock so small that it can only hold one person. They are forced to cross the stream one at a time. These double quantum dots are zero-dimensional as far as the electrons are concerned - they are trapped in all three spatial dimensions."

The scientists say their tiny new maser can produce light at different frequencies which cannot be done with other semiconductor lasers. The energy levels inside the quantum dots can be altered to produce light at different frequencies.

A research paper on the grain-sized laser was published here in the journal Science.

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