Explaining the Quantum Strategy of the U.S. Department of Defense

At the Quantum Economic Development Coalition's (QEDC) annual conference this month, John Burke, the Defense Department's top quantum research executive, reminded attendees that "after the military pays for fuel, food and ammunition for its personnel, there's not that much money left over to buy new technology. Therefore, it needs to be very inexpensive."

This perspective guides the U.S. Department of Defense's efforts in quantum information science.

Not surprisingly, the DoD is interested in all quantum information science, including quantum computers, although post-quantum cryptography and quantum sensors may be higher priorities at this time. However, issues such as the cost of quantum computing, the young stage of the technology, and the Department of Defense's clearly defined mission are dampening the Department's enthusiasm for quantum computing.

Burke, DoD's chief director of quantum science, presented DoD's efforts in QIS at the QEDC conference, acknowledging its potential while being cautious about its readiness and cost. For DoD, the bottom line (the bottom line) of quantum computing seems to be a goal we have not yet reached, although he encouraged QEDC members and the industry as a whole to continue their efforts and take advantage of DoD's growing industry outreach.

The following slides broadly demonstrate the DoD's thinking on quantum computing.

Quantum computing: the gap between current quantum computing hardware capabilities and the application space. Industry claims to shrink quantum annealing in 5 years, but that's not the Defense Department's current assessment

Burke's brief comments make it clear that the Department of Defense is keeping a close eye on developments in quantum computing, but is not jumping on the bandwagon.

"As many have noted, our strategy right now is wait and see. We seem to need to be more proactive in understanding the impact of quantum computing."

Undoubtedly, Burke didn't share all of the Department of Defense's quantum R&D activities, but it's interesting to note that he began his talk by highlighting a "cautionary tale."

"Early in my career, I was trying to develop new clocks for GPS satellites, and I want to tell you a little cautionary tale. As I've already emphasized, GPS has had a huge impact on the economy. A study a few (10) years ago estimated global GPS-based revenues to be about 227 billion Euros, while the U.S. estimate was about $56 billion per year."

"This is a huge impact. But it presupposes quantum technology in order to make atomic clocks, but the value (cost) of these atomic clocks is very low. So the Department of Defense is paying about $10 million a year for this activity, [and] the leverage is huge."

"Here's an anecdote. The chip-scale atomic clock (CSAC) is arguably one of the most successful new quantum technologies of this century. It started in 2000, it's now 2023, and we're still working on it 23 years later."

"The reason why we're doing this, when the technology itself was researched decades ago - is because it doesn't cost much to build the commodity-grade quantum clocks the Department of Defense needs. Chip-scale atomic clocks cost about a few thousand dollars each. the original reason DARPA developed this clock through multiple companies was because it needed to be available to the Department of Defense for about $100 per unit."

The work Burke is referring to is funded by the U.S. Department of Defense's Defense Advanced Research Projects Agency (DARPA) to develop a microchip-sized atomic clock for use in portable devices.

"In military equipment, it is expected to provide soldiers with better positioning and battlespace situational awareness when GPS is not available. Commercial manufacturing of these atomic clocks began in 2011.The CSAC is the world's smallest atomic clock, measuring 4 x 3.5 x 1 centimeter (1.5 x 1.4 x 0.4 inches), weighing 35 grams, and consuming only 115 milliwatts of power, and after several years of operation, it can keep time within 100 microseconds per day.In 2019, NIST demonstrated a more stable design based on rubidium atomic vibrations. This new design has not yet been commercialized."

Burke noted, "I often see this flawed belief in experts in terms of making a huge impact, as is the case with quantum computers, where they expect a huge impact in a huge market, but the value proposition is not as clear. In the Department of Defense, we need to focus more on evaluating the value proposition within the Department of Defense. That means something different than industry. I'm very concerned about that."

"So, when it comes to quantum computing, we have this dichotomy of advances in hardware and so forth. There are a lot of applications right now. But there is a gap between the two. Our current assessment is that there's a big gap between the current capabilities and the value they could have. We've been engaged in fundamental research in quantum computing for a long time, going back to the mid-1990s, if not earlier."

At this stage, Burke said, the Defense Department is looking to leverage industry resources more.

"We have new projects. darpa ONISQ (Optimization Using Noise-laden Intermediate Scale Quantum Devices), darpa US2QC (Under-explored Systems for Practical Scale Quantum Computing), and Quantum Benchmarking are three projects currently underway. We have included the Microelectronics Commons (prototyping) in the Hub as a boost to the industry base. In fact, there are a number of appropriations left for this year, and we are waiting for Congress to decide how to utilize those appropriations for additional activities, some of which will also focus on industry faces."

"So this timeline lays out the question is what do we do going forward? The answer is we don't know. But I think now is the time to try to figure that out. What are we going to do about it? There's a long list of ideas. But it can't just be limited to what algorithms are out there, what are the capabilities of particular approaches, but it has to go down to all the levels of detail: from the potential benefits, how it actually compares to classical computing, the possible way forward for all of the classical computing, and estimating the actual economic value and impact of all of these things."

"Basically, the Department of Defense needs to come up with a very strong benefits statement. What are the benefits of quantum computing, really? And then there's the cost: how much does it cost to actually build one of these devices, to run one of these devices? I think that as quantum computers evolve, the government (not to mention the Department of Defense) will have to make decisions about how to use them. We need to get ahead of the curve in the framework of making decisions."