Travis Humble is the director the Quantum Science Center (QSC) at Oak Ridge National Laboratory. QSC is one of six National QIS Research established by the U.S. National Quantum Initiative Act (NQIA) in 2018 and being overseen by the Department of Energy. Hopes are high that these centers, through their own research and in collaboration with academia and industry, will accelerate quantum information science and help lay the groundwork for a robust quantum information industry. Did we mention that roughly $2 billion is being poured into the overall NQIA?

No pressure!

Trained in theoretical chemistry Humble says he caught the quantum bug more than 18 years ago. Today he’s leading QSC’s charge which includes trying to develop the somewhat mysterious topological qubit which is largely impervious to the noise (heat, EM, etc.) that bedevils other qubit types. QSC’s mission, of course, is much broader than that. In this HPCwire People to Watch interview, Humble describes the work at QSC, explains why topological qubits are so important, and the need for quantum computing and HPC to eventually merge.

(Besides being director of QSC, Travis is editor-in-chief for ACM Transactions on Quantum Computing, Associate Editor for Quantum Information Processing, and co-chair of the IEEE Quantum Initiative. Travis also holds a joint faculty appointment with the University of Tennessee Bredesen Center for Interdisciplinary Research and Graduate Education working with students on energy-efficient computing solutions. Travis received a doctorate in theoretical chemistry from the University of Oregon before joining ORNL in 2005.)

Congratulations on your selection as a 2023 HPCwire Person to Watch. Could you briefly review the Quantum Science Center’s mission? I know there are several focus areas. What are they?

Thank you for this honor – it is an exciting time for quantum science and technology, and I am equally excited to be deeply involved in moving these revolutionary ideas forward.

The Quantum Science Center (QSC) is a U.S. Department of Energy National Quantum Information Science Research Center with a mandate to advance key concepts in quantum science and technology for the benefit of scientific discovery, national security, and economic competitiveness. The center’s leadership in topological quantum information, scientific quantum simulations, and scientific instrumentation for quantum information science directly contribute to the nation’s strategic objectives in these areas. We have built these scientific strengths through partnerships with four national laboratories, three industry partners, and nine universities focused on overcoming key roadblocks in the resilience, controllability, and scalability of quantum technologies.

Also, in the past, you’ve broadly said the QSC plans to use existing imperfect quantum computers to build more robust future quantum computers. What does that actually mean?

In the past decade, we have seen great progress in proof-of-principle demonstrations of quantum computing, and the QSC is using today’s quantum computers to design the next generation of quantum technologies. For example, the QSC is studying an exciting class of materials called quantum spin liquids that naturally host entangled particles within their crystalline structures, but simulating these real-life materials becomes a challenge for conventional approaches as the size of the computational models increase.

QSC researchers have determined that running simulations on current quantum computers can overcome these barriers and produce new insights into how quantum materials host topologically protected states. Topologically protected states are inherently resilient against the noise that can corrupt the storage of quantum information for computing and sensing systems. We are currently testing these methods on both commercial and in-house quantum computing systems. In all cases, a major technical challenge is mitigating the noise that interferes with these calculations. We are developing additional methods to mitigate these challenges, and I anticipate that the new materials we’ll discover through quantum simulations will lead to the development of more error-resistant quantum technologies in the future.

We hear a lot about digital twins – converting a thing into a digitally-defined replica that one can simulate on and play with parameters. What about this idea of quantum twins – the notion that a well-formulated experiment on a quantum computer is not a model but actually a mini version of “system” being explored? In this sense, it’s not a simulation but an actual test of a smaller version of the system in question.

Quantum simulation is a fundamental method of quantum computing that can be used to recreate the behaviors of a model system. For example, the QSC has a strong focus on analog quantum simulation, which involves embedding target quantum models directly into a physical quantum hardware system, such as neutral atoms, ions, or photons. We can then control the physical system to mimic the behaviors of the model system, and we are currently using this approach to simulate the different phases of quantum materials. Using these methods to create a “quantum twin” will require high quality characterizations of the original target system (such as a novel material) as well as an understanding of the noise sources that arise within the hardware platform. Combining these advanced capabilities creates a new platform for discovery and innovation that builds on the backbone of quantum computing.

The QSC is one just a few organizations actively exploring topological qubits. Microsoft has been their biggest champion but the technology remains unproven. I know the QSC is also exploring topological qubits. Could you provide a brief description of topological qubits, what makes them better than other modalities, and share the progress the QSC is making on their development?

Broadly speaking, topology is defined by the structure and relationships between different objects. The QSC uses these concepts for controlling the topology of quantum information. Researchers at Microsoft, which is one of our industry partners, have demonstrated that topological encoding methods help protect quantum information from noise and errors. Topologically protected states provide an inherent form of error correction and harnessing these types of qubits supports our long-term goal of enabling scalable, next-generation quantum technologies.

Today, the QSC is creating quantum materials that are expected to realize different types of topological quantum states. These materials include quantum spin liquids and topological superconductors. We eventually plan to expand these efforts to new types of qubits, but the first milestone we must reach is to experimentally validate the creation of topologically protected states and to control the information stored in these materials. We’ve made great progress towards these goals – we recently reported an experimental witness of entanglement in the chemical compound ruthenium trichloride using inelastic neutron scattering, and we are continuing to work toward experimental validations in other materials.

The traditional HPC market is undergoing substantial change, most notably blending in AI technologies – with quantum on the horizon. How do you view the relationships between these sectors: high-performance computing, AI/machine learning and quantum computing?

Quantum computing systems are complementary to high-performance computing systems, and computing architectures such as loosely integrated cloud-based approaches or tightly integrated accelerator models present workflow development options that can be tailored to different scientific applications. Of course, making these decisions will require merging the quantum computing and HPC communities, but I also expect that there will be a new emphasis on introducing requirements for quantum computers. Reproducibility and reliability are critical features for a computing application, but today’s quantum computers are still volatile components due to device noise and fidelity tolerances. I expect ongoing improvements in quantum hardware development to eventually resolve these issues but reaching this goal will require ongoing conversations between members of the quantum community and the scientists setting expectations for future applications.

What inspired you to pursue a career in STEM and what advice would you give to young people wishing to follow in your footsteps?

For those looking to pursue a career in quantum science and technology, please note that this is a new field and there are different paths to success. Like many other people in this field, I have built my career by making the connections necessary to push new ideas forward. Succeeding in this endeavor requires gathering the courage to face the challenge of uncertainty on the path to creating something new. It’s important to take advantage of any opportunities that emerge in this dynamic and creative landscape.

Outside of the professional sphere, what can you tell us about yourself – unique hobbies, favorite places, etc.? Is there anything about you your colleagues might be surprised to learn?

I am an avid soccer player, and I play about three times per week in the local league. I love the thrill of the beautiful game, and I enjoy the way teamwork creates new opportunities on the field, just like it does in the lab.

Humble is one of 12 HPCwire People to Watch for 2023. You can read the interviews with the other honorees at this link.