WHY THIS MATTERS IN BRIEF
The age of using stealth to avoid radar and other electromagnetic based detection systems is coming to an end as new quantum sensors and sensing systems will increasingly render today’s stealth obsolete.
Following on from their announcement that they’ve created the world’s first Quantum Radar system, which would, if true, render all US stealth obsolete, and are about to drop $10 Billion building a new national Quantum Research Center, China has announced that it’s now developing a new quantum “ghost imaging technology” equipped spy satellite that it says could “change the game of military cat and mouse within a decade.” They also say that existing military camouflage techniques, from the simple smoke bombs used to hide tanks or soldiers on battlefields to the hi-tech radar absorption materials on a stealth aircraft or warship, would be useless against the new technology.
Quantum ghost imaging can achieve an unprecedented level of sensitivity by detecting not just the extremely small amount of light reflecting off, or interacting with, a dim target, but also its interactions with other light in the surrounding environment in order to obtain a more detailed image of the object than is possible using traditional methods, and a satellite equipped with quantum sensors, which are millions of times more sensitive than traditional sensors, would be able to identify and track targets that are currently invisible from space, such as stealth bombers taking off at night, according to the researchers.
The Northrop Grumman B-2 Spirit operated by the US, for example, is the world’s only stealth bomber in service capable of delivering a strategic strike on an enemy, and they mostly fly under the cover of night, in part to avoid the high definition optical cameras on spy satellites. They also have a special coating to deflect or absorb microwaves of certain bandwidths produced by space based synthetic aperture radars, as well as heat suppression technology to dodge infrared sensors, and the B-2’s successor, the B-21 is expected to enter service by 2025.
Gong Wenlin, research director at the Key Laboratory for Quantum Optics at the Chinese Academy of Sciences in Shanghai, whose team is building the prototype ghost imaging device for the satellites said their technology was designed to catch “invisibles” like the B-2s.
He also said his lab, led by prominent quantum optics physicist Han Shensheng, would complete a prototype by 2020 with an aim to test the technology in space before 2025, and by 2030 he said there would be some larger scale applications.
While ghost imaging has already been tested on ground based systems, Gong’s lab is in a race with overseas competitors, including the US Army Research Laboratory, to launch the world’s first ghost imaging satellite.
The team showed the engineering feasibility of the technology with a ground experiment in 2011, and three years later the US army lab announced similar results.
“We have beat them on the ground. We have confidence to beat them again in space,” said Gong.
The plan is that the ghost imaging satellite will operate two cameras, one aiming at the targeted area of interest with a bucket-like, single pixel sensor while the other camera measures variations in a wider field of light across the environment, and the target could be illuminated by almost any light source such as the sun, moon or even a fluorescent light bulb. Alternatively, a pair of physically “entangled” or “correlated” laser beams could be generated from the satellite to light up the object and its surroundings.
By analysing and merging the signals received by the two cameras with a set of sophisticated algorithms the scientists say they could conjure up the image of an object with extremely high definition previously thought to be impossible.
Gong said darkness, cloud, haze and other negative elements impairing visibility would no longer matter.
“A ghost imaging satellite will reveal more details than the most advanced radar satellite,” he said.
“Because quantum imaging can collect data from a wide spectrum of light, the images they produce would look “more natural” to human eyes than the black-and-white radar images based on the echo of high-frequency electromagnetic waves of narrow bandwidths,” he added.
The ghost camera could also identify the physical nature or even chemical composition of a target, according to Gong. This means the military would be able to distinguish decoys such as fake fighter jets on display in an airfield or missile launchers hidden under a camouflage canopy.
Tang Lingli, a researcher with the Academy of Opto-Electronics at the Chinese Academy of Sciences in Beijing, said numerous new devices had been built, tested in the field and were ready for deployment on ground based radar stations, planes and airships.
“Satellite is the next step,” she said.
Tang said ghost imaging could be achieved using different methods in either quantum or classical physics, and it would work best with other intelligence gathering methods including optical cameras and synthesised aperture radars.
“Each detection method has its unique advantages. It depends on the circumstances and nature of the mission as to which one should be used, if not all [of them],” said Tang, who is also the general secretary of the National Committee on Remote Sensing Technology Standardisation and a supervisor of the national ghost imaging project.
Xiong Jun, a professor of physics who studied quantum optics at Beijing Normal University, said ghost imaging could become a game changer for military operations.
Xiong said he had seen ghost imaging used in ground-based radar systems and spy planes, but the satellite project had not been publicly discussed because of its sensitivity, and many engineering challenges would have to be overcome to build such a satellite, he said.
If the satellite used a natural light source such as the sun and moon, it would need to have extremely fast sensors to detect the tiny changes in light down to a few nanoseconds in order to catch the quantum physics in action.
If it used an artificial light source such as a laser, it would need to be very powerful to reach a distant target near the ground, but Xiong noted that China had built and run the world’s first and only quantum satellite, which provided a large amount of experimental data, and engineering experience, for its scientists.
He said that satellites could generate a pair of entangled laser pulses and send them to different locations on the ground, and the ghost imaging satellite would use similar techniques.
“The theory of ghost imaging has been well established and understood,” Xiong said, “the speed of application very much depends on the government and the amount of money it’s willing to spend.”
