HPE has unveiled a new optical microprocessor combining conventional electronic circuit boards with photonics that, it claims, overcomes the problems of movement and vibrations outside a device affecting its performance.
The device, designed at Hewlett Packard Labs in Palo Alto, California, integrates 1,052 optical components and represents the biggest and most complex optical microprocessor yet developed, according to HP Labs senior research scientist Dave Kielpinski.
The device is based on the Ising approach, a model for how magnetic fields of atoms interact to cause magnetism.
While every atom randomly points in one of two directions at a normal temperature, heat can affect the way in which the atoms respond, causing them to flip. But when the temperature is taken down below a certain threshold the atoms' magnetism tend to point in the same direction.
Hence, the elements in an Ising-based device can bear one of two states.
One of the problems of building such a machine is that they are extremely sensitive to movement and vibration, which can affect computation. Scaling up what have so far been small-scale projects is impractical and expensive.
According to IEEE Spectrum, though, HPE has developed a technique that is less sensitive to peturbations: "Four areas on the chip, called nodes, support four spins made of infra-red light. After the light exits each node, it is split up and combined with light from each of the other nodes inside an interferometer.
"Electric heaters built into the interferometer are used to alter the index of refraction and physical size of nearby components. This adjusts the optical path length of each light beam - and thus its phase relative to the other beams.
"The heater temperatures encode the problem to be solved, as they determine how strongly the state of one spin is weighed against another when two beams are combined. The outputs of all these interactions are then condensed and fed back into the nodes, where structures called 'micro-ring resonators' clean up the light in each node so it once again has one of two phases.
"The light cycles over and over through the interferometer and the nodes, flipping spins between phases of zero degrees and 180 degrees until the system equilibrates to a single answer."
Integrating the components onto a chip with light taking paths etched in silicon ought to overcome the problem of external vibrations and temperature swings, according to Peter McMahon, a researcher behind a similar optical computer development at Stanford University.
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