A mechanical memory

A tiny beam of silicon can be used as a mechanical memory device that is able to retain information without being connected to a power supply, reports a paper published online this week in Nature Nanotechnology. The device in this study could have applications in optical communication systems and signal processing.

The silicon beam is part of an optomechanical circuit that allows energy to be exchanged between laser light in an optical cavity and the mechanical energy of the beam. Both ends of the beam are attached to a silicon chip, and it is designed to have a slight buckle, which means that it is either in an up or down state. However, the beam can also be made to vibrate by shining a laser into the optical cavity. Hong Tang and colleagues have now shown that optomechanical amplification can be used to excite the beam into a state with high-amplitude oscillations, and that optomechanical cooling can then be used to quench these vibrations so that the beam returns to a specific state when the laser is turned off. It is this control over the final state of the beam that allows information to be written to the device. The information can be read by another laser.

Many early computers had mechanical memories, but magnetic and electronic memories dominate data storage today. The amount of energy needed to store one bit of data with the new mechanical approach is more than a million times higher than that needed to store one bit in a modern memory device, but it should in future be possible to reduce the energy requirements of the nanomechanical memories by using higher-quality cavities.

doi: 10.1038/nnano.2011.180

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