LMU physicist builds quantum systems to model complex physics

© Christoph Hohmann / MCQST · lmu.de Ludwig Maximilian University physicist Jad Halimeh is building quantum systems to explore some of the most complex phenomena in physics. Halimeh, recently appointed professor and member of the Munich cluster of excellence MCQST, crafts controlled experiments recreating exotic many-body physics, including the behavior of particles at points along a fine lattice. “We use quantum mechanics to build quantum simulators; these demonstrate exotic phenomena that are difficult to replicate on classical computers,” explains Halimeh, bridging theoretical equations with advances in quantum computing and simulation. His group recently used the Quantinuum System Model H2 chip to observe the dynamics of strings and glueballs in two spatial dimensions.

Synthetic Quantum Systems Recreate Complex Many-Body Physics This achievement builds on a strategy of directly recreating complex physical systems, employing analog quantum simulators built from ultracold atoms trapped in optical lattice cages constructed with laser light. Unlike digital quantum simulators using quantum logic operations, these analog systems embody the physics being studied, offering a distinct approach to tackling intractable problems in many-body quantum mechanics.

The team’s work focuses on lattice gauge theories, a mathematical framework where space and time are discretized, allowing for the modeling of particle interactions like those involving quarks and gluons, Quantinuum says. The inherent complexity of gauge theories typically prevents direct solutions, necessitating approximations that can limit accuracy; lattices provide a means of managing this complexity. Quantinuum’s trapped-ion technology is central to these simulations, providing a stable and controllable platform for manipulating qubits, the fundamental units of quantum information. Quantinuum was formed in 2021 by the merger of Honeywell Quantum Solutions and Cambridge Quantum, and is now publicly listed as QNT on Nasdaq, with a current headcount of about 630 people and total raised of $3.11B. The company’s recent $100M grant from the U.S. Department of Commerce, CHIPS Act, underscores its commitment to expanding quantum computing capabilities. Halimeh emphasizes the importance of intuition in his approach, stating, “I would describe myself as someone who thinks phenomenologically. For me, intuition is the most important thing. I gather clues, build a bigger picture from them, and try to understand what is really happening. Only then do I look for the simplest possible mathematical description.” This emphasis on understanding the underlying physics before seeking mathematical formalization guides his team’s investigations into phenomena like hadronization, the process by which quarks bind together to form composite particles. The initial state of these systems is known, but the precise mechanisms governing their final configuration remain elusive, requiring what Halimeh describes as achievable through quantum simulation. Demonstrating that quantum simulators can outperform classical computers in specific tasks is a key driver of this research. This comparative analysis allows them to identify areas where quantum simulations offer a demonstrable advantage, potentially revealing new insights into complex physical systems.

The team’s work is not solely focused on theoretical advancement; it also is a testing ground for the latest quantum processors, with each iteration reaching 98 qubits in capacity. He notes the vital role of experimental physics in accelerating progress, stating, “Similarly, they come to us with new, elegant methods and ask: What can we investigate physically with this? What phenomena could we make visible? Without experimental physics, we would progress much more slowly. We learn a great deal from each other.” This collaborative spirit extends to partnerships with companies like Synopsys, integrating quantum computing into engineering design, and Rolls-Royce, applying quantum simulations to improve fluid dynamics modeling for gas turbine design. The potential applications of this research extend beyond particle physics. Even the legacy of past physicists informs Halimeh’s work; he cites the example of Emmy Noether, stating, “Not only because of his scientific achievements and creativity, but also because of his life’s journey – the difficulties he had to overcome, the persecution he faced during the Nazi era, his independent thinking. He is a great role model for me.” This commitment to both scientific rigor and historical perspective underscores the broader significance of Halimeh’s research, bridging the gap between fundamental physics and real-world applications while honoring the legacy of those who paved the way. The integration of Quantinuum’s Helios quantum computer with supercomputing expertise, as seen in the Rolls-Royce partnership, further exemplifies this convergence of disciplines, promising advancements in complex simulations across diverse fields. That is also why major tech companies are interested in our research: We provide test cases and applications for their most advanced digital processors, each with more than 100 qubits. Jad Halimeh, professor of quantum physics at LMU and a member of the Munich cluster of excellence MCQST Analog and Digital Approaches to Quantum Simulation The distinction between analog and digital quantum simulation hinges on how faithfully a target physical system is reproduced, with Halimeh’s group actively pursuing both avenues to model complex phenomena like quark interactions. Digital quantum simulators, using quantum logic operations, provide greater programmability, allowing researchers to explore a wider range of theoretical models, but require translating the physical problem into a sequence of quantum gates. This comparative approach extends beyond mere methodology; it informs a systematic search for scenarios where quantum simulation demonstrably outperforms classical computation. “We deliberately search for parameter ranges where even our best classical methods come up against their limits,” Halimeh explains, emphasizing the need to identify problems intractable for conventional computers. The goal is not simply to replicate existing classical results, but to access regimes inaccessible by any other means, revealing new insights into the behavior of matter at extreme conditions. Recent experiments conducted in collaboration with Quantinuum have yielded the largest two-dimensional realization of lattice gauge theories to date, a significant step toward simulating more complex, three-dimensional systems. These simulations, performed on the Quantinuum System Model H2, utilize trapped-ion qubits, individual ions suspended and controlled by electromagnetic fields, to represent the fundamental building blocks of the lattice. The company’s technology, based on trapped-ion qubits, offers advantages in terms of coherence and connectivity, important for performing complex simulations.

Lattice Gauge Theories Model Quark-Gluon Dynamics This achievement builds upon the team’s established expertise in simulating these theories, positioning them as a leading group for systems in both one and two dimensions, a distinction earned through a reciprocal interplay of theoretical modeling and experimental validation. “It’s a reciprocal game: We develop theoretical models that challenge our experimental colleagues at MCQST,” Halimeh explains, highlighting the collaborative nature of their work and the iterative process of refining both theory and simulation techniques. Unlike digital quantum simulators that rely on quantum logic operations, this analog method offers a different pathway to exploring complex phenomena, allowing for the direct observation of physical processes. Achieving these snapshots requires overcoming limitations inherent in classical computation, which struggles with the complexity of lattice gauge theories and is often restricted to small system sizes and short simulation times. A quantum computer, however, offers the potential to model larger systems and extend the duration of simulations, providing a more complete picture of hadronization. Halimeh’s team is focused on implementing a Hamiltonian operator, a mathematical blueprint describing all interactions, in three spatial dimensions, allowing them to explore the full dynamics of quark-gluon binding. This operator incorporates parameters governing particle hopping, local interactions, and spin, enabling precise control over the simulation. “Ideally, the quantum computer should reproduce exactly the physics encoded in this model,” Halimeh states, outlining the goal of achieving accurate and reliable simulations. The pursuit of this accuracy is driven by a broader ambition: to demonstrate quantum advantage, the ability of a quantum computer to solve problems that are intractable for even the most powerful classical computers. “My second pillar is what’s known as quantum advantage,” Halimeh explains, indicating a strategic focus on identifying problems where quantum simulation can surpass classical methods. This requires not only developing sophisticated quantum algorithms but also carefully selecting parameter ranges where classical simulations fail, pushing the boundaries of both quantum and classical computation. Quantinuum, formed in 2021 by the merger of Honeywell Quantum Solutions and Cambridge Quantum, is a quantum computing company pursuing the first universal fault-tolerant quantum computer. The company, now publicly listed on Nasdaq as QNT with about 630 people and total raised: $3.11B, develops trapped-ion quantum hardware and software, including the 98-qubit Helios system. This technology allows for precise control over individual qubits, essential for implementing the complex Hamiltonian operators required for lattice gauge theory simulations, according to Quantinuum. The company’s partnerships, including collaborations with Synopsys to integrate quantum computing into engineering design and with HPE to combine high-performance computing with quantum systems, demonstrate a commitment to translating research into practical applications. We find ourselves at a productive intersection of many-body quantum physics, quantum simulation, and numerical simulations on classical computers. Jad Halimeh, professor of quantum physics at LMU and a member of the Munich cluster of excellence MCQST Quantum Simulators Investigate Hadronization Timescales The dynamics of quark binding, a process central to hadronization, are now under investigation using quantum simulators, revealing discrepancies between theoretical predictions and observed timescales. These recent experiments represent the largest realization of lattice gauge theories achieved to date, offering a new avenue for understanding the fundamental forces governing particle physics. The approach relies on a reciprocal interplay between theoretical modeling and experimental validation, a process Halimeh describes as a His team begins with key equations, developing numerical models subsequently tested at the Munich cluster of excellence MCQST. This collaborative environment allows for a unique intersection of theory and experiment, challenging both sides to refine their understanding, the company says. A key challenge lies in the mathematical complexity of gauge theories, which often defy direct solution. Lattice formulations offer a pathway to manageability, but even these require substantial computational resources. “We are trying to understand exotic quantum mechanical many-body phenomena,” Halimeh states, emphasizing the need for tools beyond the reach of classical computation.

The team is also exploring the IBM Nighthawk chip with superconducting qubits, conducting scattering experiments within the framework of gauge theory, Quantinuum reports. These endeavors are complex and time-consuming, demanding a comprehensive perspective to identify connections between seemingly disparate areas of research. The current focus extends beyond simply replicating known results; Halimeh’s group actively seeks parameter ranges where classical methods falter. Hadronization, with its intricate dynamics, presents a promising test case for realizing this advantage. One persistent puzzle concerns the unexpectedly short timescales observed for quark binding. While the initial state of the system is well-defined, the precise mechanisms governing the final bound state remain elusive. To unravel this mystery, the team seeks to capture temporal snapshots of the process, akin to frames in a film, a feat best achieved with a quantum simulator. This broad network of partnerships underscores the versatility and potential of Quantinuum’s technology across diverse scientific and industrial applications. Halimeh’s team is currently comparing highly precise numerical simulations with results obtained from quantum simulations conducted in collaboration with Google Quantum AI, IBM Quantum, and Quantinuum. This multifaceted approach, combining theoretical insights, experimental validation, and advanced computational tools, promises to shed new light on the fundamental processes governing the universe at its most basic level.

The team’s work is not merely about solving equations; it is about building a deeper understanding of the quantum world and unlocking its potential for transformative discoveries. Ideally, the quantum computer should reproduce exactly the physics encoded in this model. Jad Halimeh, professor of quantum physics at LMU and a member of the Munich cluster of excellence MCQST That is also why major tech companies are interested in our research: We provide test cases and applications for their most advanced digital processors, each with more than 100 qubits. Jad Halimeh, professor of quantum physics at LMU and a member of the Munich cluster of excellence MCQST Source: https://www.lmu.de/en/newsroom/news-overview/news/quantum-physics-the-bridge-builder-e2a23d6d.html More like thisPhysicsRESCEU Symposium Will Cover Quantum Cosmology and String TheoryQuantum Research NewsA 4n/3 T-gate count beats the old 3n/2 barrier for quantum opsQuantum PhysicsBasque Country UPV Team Finds Stable Towers Within Gauge TheoriesQuantum Research NewsResearchers Prove Quantum Shadow Advantages Survive NoiseStay currentSee today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals. Tags: