Chinese Advances in Quantum Sensing

This piece builds upon prior research and analysis on Chinese advances in quantum information science and quantum technologies, previously featured in China Brief in the series “China’s Quantum Leap,” parts one and two.

Quantum sensing could be used in a number of technologies with direct military applications. In particular, quantum radar can be used to detect targets that cannot be discerned through conventional radar, and quantum navigation similarly leverages quantum properties to create a precise form of positioning system that may eventually replace GPS. Together, such technologies could be critical to China’s future military capabilities and might become a key focus of U.S.-China technological competition.

Context for China’s Advances in Quantum Information Science

These programs have started to enable significant advances in quantum communication and quantum computing. In 2016, China launched the world’s first quantum satellite, Micius, which could become the first piece of a global quantum network for uncrackable communications (Science Mag, June 2017). In March, Chinese scientists succeeded in entangling 10 superconducting qubits, an important step towards future quantum computing (Physics World, April 2017). In early August, Chinese scientists announced their success in experiments involving Micius, not only demonstrating successful ultra-long-distance quantum teleportation, a key step towards a global “quantum internet,” but also succeeding in the first-ever realization of space-to-ground quantum key distribution, a milestone for quantum communication (Nature, August 9, 2017; Nature, August 9, 2017; Xinhua, August 10, 2017). While these developments have received considerable attention in official Chinese and international media, Chinese scientists have also actively pursued advances in quantum sensing, which have often remained below the radar.

Ongoing Research and Development Efforts in Quantum Radar and Navigation

To date, details about China’s progress in quantum sensing has been relatively limited, likely because of its more obvious and direct military applications. Despite these constraints, it is possible to evaluate initial advances in quantum radar and quantum navigation. Of particular note, China’s apparent success in the development of quantum radar was prominently featured in September 2016, when Chinese scientists announced their creation of a single-photon quantum radar, which takes advantage of entanglement between photon pairs, capable of detecting targets up to 100 kilometers away with high accuracy (PLA Daily, September 13, 2016; CETC, September 18, 2016). Reportedly, the range of this quantum radar was five times that of a laboratory prototype jointly created in 2015 by an international team of researchers (Phys.org, February 26, 2015). This test appeared to constitute a notable advance and an indication that Chinese research in quantum sensing has already progressed considerably.

Despite the limitations of the available information, it is nonetheless feasible to gauge advances to date in quantum radar and quantum navigation based on a review of ongoing research and development efforts in these technological domains. Although this listing is not comprehensive, it provides an initial overview of the scope and scale of these efforts.

Quantum Radar:

Quantum Navigation:

The number of research institutes pursuing quantum radar and navigation, as well as the funding available through national science and technology plans, hint at a state-driven national push to advance these technologies. The reports of prototypes and apparent advances also indicate that Chinese researchers may be making real strides toward the operationalization of these quantum capabilities.

Patents Point to Progress

To date, Chinese scientists and research institutes have filed a number of patents related to quantum radar and quantum navigation. Overall, the number of Chinese patent filings in quantum information science tend to rank first in the world or second to the U.S. (The Economist). While the ecosystem for research and development described above indicates the scope and scale of these efforts, available patent filings are perhaps a better gauge of real progress:

Quantum Radar

Quantum Navigation

Although it is difficult to evaluate the maturity of this research from the information provided, several of these patents serve as at least a rough indication that these research efforts have reached a point such that future applications and intellectual property has become a concern.

The Military Applications and Strategic Implications of Quantum Sensing

China’s rapid advances in quantum information science and the associated technological applications demonstrate its ambitions to lead global innovation in such strategic frontier (æ??ç?¥å??) technologies. Relative to quantum computing and quantum encryption, quantum sensing has the most direct and impactful military applications. As the electromagnetic spectrum becomes increasingly crowded in times of peace and contested in times of war, the ability to ensure trust in sensors and operate independently of the spectrum’s limitations will be critical. Certain applications of quantum sensing, including quantum radar, imaging, and navigation, could change the dynamic and use of the spectrum in ways that could be highly disruptive in future warfare.

Potentially, quantum radar could nullify stealth technologies and advanced forms of radar jamming. In this regard, the realization of quantum radar could enable the PLA to overcome superior U.S. stealth capabilities, undermining this critical pillar of U.S. military power. Indeed, commentary in PLA media at the time the test of a prototype quantum radar was announced highlighted quantum radar as the “nemesis” of today’s stealth fighter planes with “remarkable potential” on the future battlefield (PLA Daily, September 22, 2016). In addition, more theoretical descriptions of quantum radar suggest that it could be able to defeat radar jamming techniques, such as digital radio frequency memory (DRFM) jammers, which spoof a radar’s broadcasted signal to conceal an aircraft’s true location. Either application would nullify or significant limit the use of both passive (stealth) and active (DRFM jamming) electronic countermeasures in enemy space.

In any potential conflict with China, the use of stealth would be a strategic imperative for the U.S., critical to enable naval vessels to come within striking distance of the Chinese mainland and for aircraft to penetrate Chinese airspace to hold Chinese operational assets at risk. Therefore, quantum radar would be massive disruptive force—an “offset technology”—within the PLA’s suite of anti-access/area denial (A2/AD) or “counter-intervention” capabilities. If operationalized, quantum radar could not only undermine the U.S. advantage in stealth but also inherently increase the potential costs of war, forcing the United States to accept higher operational risk and nullifying billions of dollars spent on stealth coating for platforms operating in the Western Pacific.

Looking forward, quantum technology could have major implications for multiple aspects of future military operations. The U.S. Air Force Scientific Advisory Board noted in a recent report that quantum clocks and quantum sensors would merit further investment, since enhanced timing precision could enhance Air Force missions and capabilities, including SIGINT, counter-DRFM, electronic warfare (EW), and also more robust communications (AFSAB, 2016). The same report noted that quantum magnetometers, which enable quantum navigation, could be “an important part of achieving GPS-denied advantage,” including because quantum inertial sensing is not susceptible to jamming.

Similar logic about the utility of quantum navigation is evidently at play in PLA thinking. The realization of quantum navigation could allow for a “new generation of inertial navigation,” enabling high-precision navigation without GPS, as researchers from the National University of Defense Technology have noted (CNKI). This so-called “quantum compass” would be particularly useful for submarines and other maritime platforms for which it could enable the pinpointing of their position with high levels of accuracy. Quantum navigation could thus potentially liberate Chinese operational platforms from dependence on space-based positioning systems, which can be easily jammed, while the PLA concurrently becomes ever more able to hold U.S. space systems at risk through advancing its counterspace capabilities.

Quantum Uncertainties and Future Developments

Could China surpass the U.S. in quantum sensing? Certainly, active Chinese efforts to pursue advances in quantum radar and navigation, supported and accelerated by the ample funding devoted to quantum information science, demonstrate the PLA’s focus on the pursuit of innovation in emerging technologies with highly disruptive applications. Since research and development appear to remain at the prototype stage for the time being, the potential and timeframe for their realization on the battlefield remain uncertain at this point. While technologies like quantum computing and encryption would offer relatively balanced, though disruptive, capabilities, the likely asymmetries in operations for China and the U.S. creates conditions such that quantum sensing, and quantum radar in particular, could give China a much greater advantage at the expense of core aspects of U.S. military power, such as stealth. Considering the disruptive potential of quantum radar and navigation, the PLA’s progress in these quantum capabilities reflect an integral aspect of its efforts to compete with the U.S. in technological and defense innovation.

Elsa Kania is an analyst focused on the PLA’s strategic thinking on and advances in emerging technologies. Her professional experience has included working at the Department of Defense, the Long Term Strategy Group, FireEye, Inc., Harvard’s Belfer Center, and the Carnegie-Tsinghua Center for Global Policy. She is fluent in Mandarin Chinese.

Stephen Armitage is a former DOD analyst, US expat and researcher primarily focused on Chinese information operations and emerging tech.

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