MIT Professor of Mechanical Engineering Seth Lloyd has found that a peculiar quantum-physics property called entanglement can be harnessed to make detectors--similar in principle to radar systems used to track airplanes in flight or ships at sea--that are as much as a million times more efficient than existing systems. In addition, beams of entangled light could be swept across a scene to reconstruct a detailed image, with a similar improvement in efficiency.
Radar for tracking objects in space use power levels of about 500kw One million times more energy efficient means 100 watt power levels.
High power weather radar operates at 10 kw to 60 kw
CT scans use about 100 watts.
One million times less power means that megawatts become watts, kilowatts become milliwatts and watts become microwatts.
The new findings, being reported this week in the journal Science, are purely theoretical, but Lloyd says that laboratory experiments have already proven the feasibility of both the light sources and the detectors needed for such a quantum-based photodetection system, so he anticipates that within a year it should be possible to build a laboratory-scale system to demonstrate the new concept.
"It should be possible to have at least a proof-of-principle demonstration within six months to a year," Lloyd said.
For example, military applications could include improved night-vision systems, which send out beams of infrared light--invisible to the naked eye--to sweep across a scene, and then use an infrared detector to reconstruct an image from the light that is reflected back. A more efficient system, using the quantum-entanglement effect, would make it much more difficult for an adversary to detect the fact that such a system was being used, because there would be so much less infrared light needed to provide the illumination.
Theoretically, such a system could be used to allow medical diagnostic systems such as CT scans to work with a vastly reduced X-ray output, thereby making them much safer for the patient, but such applications would be much further in the future. It could also someday be used for safer microscope imaging of living organisms.