MIT research enhances high-speed computers

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. (AFPN) --  Air Force-sponsored research at the Massachusetts Institute of Technology is accelerating the development of quantum, or high-speed, computers which help Air Force specialists with cryptoanalysis, or 'code-breaking,' microwave electronics and materials science.

Chief researcher Dr. William Oliver of MIT's Lincoln Laboratory and Research Laboratory for Electronics and his team, in collaboration with MIT professors Terry Orlando, Leonid Levitov and Karl Berggren, have developed what they call amplitude spectroscopy. This technology analyzes how an atom responds to different amplitudes of electromagnetic radiation at a fixed frequency in order to extract its energy-level structure, or spectroscopy, over broad bandwidth.

According to Dr. Oliver, the group has demonstrated spectroscopy using superconducting artificial atom structures that use two superconductors linked by a non-conducting barrier.

"When the atoms are cooled to ultra low temperatures using dilution refrigeration followed by microwave-cooling -- similar to laser-cooling with atoms -- they exhibit energy levels akin to a natural atom or molecule," Dr. Oliver said.

The fabrication of such structures is unique and requires special tools. Most researchers use ultra thin aluminum film to create artificial atoms.

"We use niobium in a semiconductor-based, multi-layer fabrication process that uses optical lithography and chemical-mechanical planarization," Dr. Oliver explained. "One of the key accomplishments of our work is that we have been able to fabricate the deep-submicron Josephson junctions necessary to realize artificial atoms."

As the researchers learn more about these superconducting structures, they will advance the technology needed to develop quantum computers and technology for present day and the future.

"In the long-term, artificial atoms can be used as the 'quantum bits,' or qubits, of quantum computing, a challenging technology which drives near-term innovations," Dr. Oliver said. "For example, the deep-submicron Josephson junctions can also be used with a classical computing technology, which can reach 100 GHz clock speeds or more."

His team has had several recent successes that were all funded by the Air Force Office of Scientific Research. These include: 
--  Mach-Zehnder interferometry in a strongly driven superconducting qubit 
--  Microwave-induced cooling of a superconducting qubit. 
--  Amplitude spectroscopy of a solid-state artificial atom

"The key challenge to our research is maintaining funding stability and continuity," Dr. Oliver said. "We have been fortunate to have been funded by the Air Force for several years, but we now find ourselves looking for new programs to continue this work. Once we lose the momentum, it is very challenging to get it back."


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