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A laser concept developed by Pitt physicists could surpass a 60-year-old limitation

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  • Technology & Science
  • Faculty
  • Department of Physics and Astronomy
  • Kenneth P. Dietrich School of Arts and Sciences

Maser? Mamer? Lamer? Whatever it is, it’s not technically a laser — but it could soon do the job of one better than any that exist today.

A team of Pitt physicists recently published a design that would surpass a theoretical limit on the effectiveness of lasers that’s barely changed in more than 60 years, opening new potential applications and maybe even necessitating a name change for the technology.

Ideally, a laser would maintain a pure color no matter how long it shines, a property that physicists refer to as coherence. “If a laser is coherent, that’s like a really good clock,” explained Department of Physics & Astronomy Assistant Professor David Pekker in the Kenneth P. Dietrich College of Arts & Sciences. “But in real life, that’s not how lasers work.”

Instead, they drift. The frequency of light waves they emit, which influences how pure the beam’s color is, changes slightly over time. That’s because the amount of light bouncing around inside of a laser alters the color that the laser ultimately produces. The process is called stimulated emission, a phrase that makes up the S and E in the acronym LASER — and which the Pitt team’s design bypasses entirely.

What their design calls for is replacing components of a traditional laser to better control the flow of light, making use of the building blocks of quantum computers that have been developed over the last decade. “In quantum computers, you have qubits, these are basically like atoms in the laser, and you have cavities,” Pekker said. “So why not just try to build the laser out of quantum computer components?”

Their calculations show that the resulting microwave laser design would have a coherence far higher than the previously proposed limit, which has budged only once since 1958. The team, including researchers from the labs of Department of Physics & Astronomy faculty members Gurudev Dutt and Michael Hatridge, published their design in the journal Nature Communications last month.

Few people would ever have the need for a laser with the ultra-high coherence enabled by the new design, but there are several areas where it could come in handy. Pekker cites astronomical uses like making ultra-fine measurements of gravitational waves, as well as precise timekeeping and quantum computation. And the laser may not stay theoretical for long: Pitt physics PhD student Maria Mucci is currently working on building one.

The design got its start not during frustrated solo scribblings or grueling late nights in the lab but from, as Pekker puts it, “drinking too much coffee” while the three groups of physicists, each with different specialties, bounced ideas back and forth. “It’s a really good example of how we can do better by talking to each other and not just going to our offices and shutting the door,” he said.

Since the new technology no longer falls under the traditional definition of a laser, the team’s caffeine-fueled brainstorms also produced a few potential names — Hatridge’s addition of an “m” for metronomic, for instance, created the aforementioned “lamer.”

They’re still workshopping it.

“Coming up with a good name is important, but we haven’t managed it yet,” Pekker said. “Naming stuff is hard.”

 

— Patrick Monahan