Broad interdisciplinary efforts at the Quantum Systems Accelerator (QSA) advance the three major modalities in quantum computing: neutral atoms, trapped-ion systems, and superconducting circuits. With multiple avenues explored in the quantum science endeavor, QSA’s technology coordinator helps Center leadership see the big picture and advises on new approaches.
MIT’s William D. Oliver, who has a background in electrical engineering, serves in this role at QSA. Oliver is a recognized leader in the field with more than 20 years of experience in the quantum engineering of superconducting quantum circuits. Quantum engineering integrates the theory of quantum mechanics with electrical and electronic engineering, systems engineering, material science, and computer science for the practical applications of quantum information science.
THE PROMISE
In a one-on-one interview, Oliver recently shared his thoughts.
“If you look at the history of experimental quantum computing, the first 15 years was trying to figure out if these qubits were going to work. And that’s for any of the three technologies advanced at QSA,” explained Oliver. “What’s changed in the last five to eight years is that we now know that the qubits work, and yet there’s a tremendous amount of engineering required to bring these technologies out of the lab and to a technical reality. That’s what QSA is all about, accelerating from where we are today and addressing systems issues with the constraints currently in existence.”
Excited about the future of the field, Oliver describes how new technologies and sophisticated devices will enable scientific discovery and broaden our understanding of physics and the universe. He said:
“By building these larger quantum mechanical systems, it would be interesting to see if we gain additional insights and a deeper understanding into how quantum mechanics works. Not that we’re going to prove it wrong, but we may begin to learn some of the why’s and the how’s. In QSA, we have plans across all three modalities to investigate physics at scales approaching and even entering the quantum advantage regime. An example is with neutral atoms, which can emulate certain lattice models very well. And when these lattice sizes increase to the hundreds or even thousands of qubits, they’re going to enable breakthroughs in theoretical physics that cannot be calculated on a classical computer. Of course, they are not universal quantum computers that can be programmed to solve every problem, but they have enough qubits to give insight into new phases of matter, for example.”
THE CHALLENGES
Despite the significant progress achieved over the past years, with many recent milestones driven by QSA partners and researchers, there’s another dimension to the field’s development. Quantum engineering requires co-design.
Oliver explained how as with any complex technological endeavor, broad engineering skill sets take theoretical concepts and turn them into working systems.
“As a quantum system engineer, sometimes I may need to dial back or compromise on one aspect of the system so that someone else can dial up another aspect to increase overall system performance. Or maybe we can come up with a different approach where there is no need for compromise. However, the only way that we can identify this tradespace is if we’re talking with each other and engaging. This need for system thinking, or ‘co-design’ in today’s jargon, is why we need to have quantum engineering front and center. How are we going to engineer quantum systems? And what are the abstractions that we need to make so that other engineers – those who may not be trained in quantum physics, but who have deep engineering expertise – can contribute to this endeavor? We need to be able to build a bridge between their knowledge base and the needs of quantum computing.”
QSA regularly conducts Center-wide science meetings so that researchers can share lessons learned, explore what others work on, as well as enable inclusion and belonging for an increasingly diverse workforce. This approach breaks through research silos, guides diversity, equity, and inclusion (DEI) values, and fosters the cross-pollination of ideas needed to think and design at the systems level. Early-career researchers at different QSA partner institutions, for example, have discovered alternatives to problems they had been working on as a result of these conversations and meetings with other members.
“The spirit of QSA is a deep recognition that it takes an entire team to make this transition from the lab to a technical reality in the marketplace,” said Oliver. “It’s truly going to take a village, and everybody has an essential role in quantum technology development. We need people to bring their ideas, experiences, and knowledge base and then be able to make the pivot to quantum science and engineering problems. ”
LOOKING AHEAD
Driven by the advances in quantum error resiliency, researchers can currently simulate and compare the ideal results of a quantum computer with classical computers for most applications. However, as devices increase in complexity, many quantum verification, validation, and control models will not be possible to verify classically. Therefore, researchers are starting to look ahead to “logical qubits.” A logical qubit combines multiple physical qubits in a way that protects against noise, so that it can be used as one reliable qubit for quantum computation.
Oliver offered his broad perspective on how to move forward from the current NISQ quantum era toward the future of logical qubits and what that would mean for the demonstrations of quantum advantage.
“The first thing we’ll need to do to transition to a post-NISQ era is to develop logical qubits, error-corrected qubits, which enable us to gain system-level resilience (logical qubits) by adding redundancy (more physical qubits). And although logical qubits aren’t perfect, they fail much less often than physical qubits. This error-corrected regime allows us to perform calculations with logical qubits that have lower error rates than their constituent physical qubits. That translates to more operations (longer circuit depth) before things fall apart. When we can operate the system for times longer than the coherence time of any individual physical qubit, we encounter new possibilities to perform algorithms that we simply can’t do in the NISQ era. Demonstrating quantum advantage should be straightforward at that point. We would be able to implement algorithms that give us answers to meaningful problems that a classical computer cannot calculate. Likewise, another dimension in the error-corrected regime is the virtuous cycle resulting from the commercialization of these solutions. Revenue generated from the commercialization of these quantum computing prototypes is then used to advance tomorrow’s next-generation processors, and so forth.”
QSA advances quantum engineering by co-designing the solutions needed to build working quantum systems that outperform today’s computers and accelerate the maturation of commercial technologies.
Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab’s facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy’s Office of Science.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.
Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.
The Quantum Systems Accelerator (QSA) is one of the five National Quantum Information Science Research Centers funded by the U.S. Department of Energy Office of Science. Led by Lawrence Berkeley National Laboratory (Berkeley Lab) and with Sandia National Laboratories as lead partner, QSA will catalyze national leadership in quantum information science to co-design the algorithms, quantum devices, and engineering solutions needed to deliver certified quantum advantage in scientific applications. QSA brings together dozens of scientists who are pioneers of many of today’s unique quantum engineering and fabrication capabilities. In addition to industry and academic partners across the world, 15 U.S. institutions are part of QSA: Lawrence Berkeley National Laboratory, Sandia National Laboratories, University of Colorado at Boulder, MIT Lincoln Laboratory, Caltech, Duke University, Harvard University, Massachusetts Institute of Technology, Tufts University, UC Berkeley, University of Maryland, University of New Mexico, University of Southern California, UT Austin, and Canada’s Université de Sherbrooke. For more information, please visit: www.quantumsystemsaccelerator.org
