BOULDER, Colo. One of the oldest forms of computer memory is back againbut in a 21st century microscopic device designed by physicists at the National Institute of Standards and Technology (NIST) for possible use in a quantum computer.
The NIST team has demonstrated that information encoded as a specific point in a traveling microwave signalthe vertical and horizontal positions of a wave pattern at a certain timecan be transferred to the mechanical beat of a micro-drum and later retrieved with 65 percent efficiency, a good figure for experimental systems like this. The research is described in the March 14 issue of Nature.*
"We believe the mechanical drum motion could be used as a kind of local memory for quantum information systems," NIST physicist Konrad Lehnert says. "These experiments live at the boundary between classical and quantum systems."
The technique harks back to "delay line memory" that was used in some of the earliest electronic computers, including NIST's own 1950s computer, SEAC.** Those devices were fairly simple. They temporarily stored values during computation in the form of acoustic waves traveling down a column of mercury or other fluid. By contrast, the NIST micro-drum memory would exploit a mechanical form of quantum physics.
NIST scientists introduced the micro-drum in 2011.*** The micro-drum is embedded in a resonant circuit and can beat at different frequencies. By applying microwaves at specific frequencies, researchers can achieve rapid, reliable exchanges between the circuit's electrical energy, in the form of microwave photons (light particles), and the drum's mechanical energy in the form of phonons (units of vibration).
An applied microwave tone can cool the drum down to its lowest-energy ground
state, with less than one quantum of energythe quantum regime, where the drum can store and convert quantum information. The same interaction transfers information from microw
|Contact: Laura Ost|
National Institute of Standards and Technology (NIST)