Even as quantum computers have made strides from theoretical concept to multi-million qubit reality, a major stumbling block persists: there's a severe lack of practical algorithms tailored to run on these radically different machines and solve pressing real-world problems.

To help bridge this "quantum algorithm gap," Google has launched a major new $5 million competition challenging researchers around the world to develop and test quantum algorithms squarely aimed at delivering transformative benefits across fields like climate science, materials design, medical drug discovery, and more.

Dubbed the XPRIZE Quantum Applications competition, the three-year global contest from Google's philanthropic arm Google.org hopes to seed the quantum computing ecosystem with a broad array of algorithms optimized for tackling major societal challenges aligned with the United Nations' 17 Sustainable Development Goals.

"Most quantum algorithms have been studied mainly in the context of abstract mathematical problems, and less work has been devoted to evaluating these algorithms for specific, real-world use cases," said Brigitte Hoyer Gosselink, director of Google.org, in the competition announcement. "While there are many reasons to be optimistic about the potential of quantum computing, we still don't know exactly how, when, and for which real-world problems this technology will prove most transformative."

Although quantum supremacy milestone experiments have demonstrated quantum computers can vastly outperform classical machines on certain contrived computational tasks, translating those theoretical speed-ups into practical, scalable algorithms for immensely complex real-world use cases has remained elusive. Google's newly unveiled competition aims to incentivize and accelerate that crucial transition.

The contest is divided into two parallel tracks aimed at tackling both near-term and long-term quantum applications. For the Noisy Intermediate-Scale Quantum (NISQ) computing era of today's relatively small, noisy, and error-prone quantum devices, the competition calls for proposals leveraging these systems to demonstrate an early "quantum advantage" for highly targeted use cases.

But Google also recognizes the limitations of NISQ systems and the belief that large-scale, error-corrected, fault-tolerant quantum computers will ultimately be needed to unlock quantum's full potential. So the competition simultaneously seeks proposals for quantum algorithms suited for these future, far more powerful quantum systems.

"Although we believe that useful applications can be found in the NISQ era, the main impact of quantum computing will be achieved after the creation of large-scale quantum computers," said Ryan Babbush, head of quantum algorithms at Google Quantum AI. "And we can identify these applications now to have them ready for implementation as more powerful hardware is developed."

To spur submissions along both tracks, the XPRIZE Quantum Applications contest includes a sizable $5 million prize pool. 20 semi-finalists will be awarded $50,000 each, with the five highest-scoring finalists splitting $1 million. The three grand prize winners judged to have the highest-impact quantum algorithms will then split the remaining $3 million.

Beyond the cash rewards, Google hopes to leverage the power of an open competition to help pinpoint the most promising quantum use cases and add rocket fuel to their development paths. Proposals will be evaluated based on metrics like positive societal impact, speed compared to classical algorithms, and the minimum quantum computing resources required to demonstrate an advantage.

Some likely target domains based on early quantum algorithm research include areas like:

• Modeling chemical reactions and dynamics to accelerate drug discovery and design higher-performing materials, catalysts and battery components
• Optimizing supply chains, logistics, finance portfolio optimization and other challenging operational scheduling and planning problems
• Simulating complex natural phenomena like superconductors, fusion plasmas, and molecular dynamics to unlock new scientific frontiers

However, Google is intentionally keeping the competition open-ended to attract out-of-the-box thinking and uncover quantum algorithm breakthroughs well beyond incremental improvements on known use cases.

"We want teams to have the freedom to define quantum applications beyond those explored before," the competition website states.

While Google is anchoring the competition through its Google Quantum AI group and philanthropic units, the open nature of the XPRIZE is also aimed at fostering broad collaboration between industry, academia, startups, and individual researchers. Cross-pollination, argues Google, will be critical to seeding a self-sustaining ecosystem catalyzing a steady stream of real-world quantum innovation.

As conventional computing slams into the limits of Moore's Law, Google and many experts believe quantum's unique computational properties - like superposition, entanglement, and quantum tunneling - could allow it to blast past the brick walls holding back today's machines. But first, the technology will need to evolve from physics experiment into practical solution.

With a hefty incentive pot now on the table, Google is betting its XPRIZE lures forth the quantum killer apps needed to make that pivotal transition a reality.