CAREER: Probing Quantum Matter using Programmable Quantum Simulators

NONTECHNICAL SUMMARY Recent advances in the ability to control quantum devices are ushering in new approaches to study the rich and complex physics that emerges from quantum systems of many interacting particles such as quantum materials. One promising approach is quantum simulation, in which a quantum device with several tunable parameters is carefully manipulated to emulate the physics of various other systems of interest. Despite their promise, present-day quantum devices are still far from ideal, as their operations are noisy and the ability to control them is imperfect. The central challenges are (i) to understand how to optimally exploit such devices to explore the largest wealth of physics possible despite the restrictions and (ii) to extract physically meaningful information from potentially noisy and limited data. Here, the principal investigator proposes to address these challenges through novel ideas from theory leveraging recent advances in quantum information science and machine learning. The principal investigator will pursue this research goal in parallel with a diverse set of outreach activities fostering high-school and undergraduate student research, attracting talented students, and preparing them as the next generation scientists. TECHNICAL SUMMARY Understanding, controlling, and harnessing the quantum dynamics of increasingly complex many-body systems are among the most important goals of quantum science research. The first half of the research component aims to develop practical methods to achieve these goals, focusing on existing experimental capabilities. In particular, the PI and his team will develop methods to robustly engineer effective Hamiltonians of a given quantum hardware by means of optimized pulsed controls and to perform advanced measurements of arbitrary observables or nonlocal properties by utilizing information scrambling. These capabilities are otherwise difficult owing to limitations in quantum control of current devices, calling for novel theory ideas. Leveraging improved capabilities, the research team will pursue probing exotic emergent phenomena such as deconfined quantum criticality using existing quantum simulators. Deconfined quantum criticality may plan an important role in understanding high temperature superconductors and other quantum materials. Successful observations of exotic emergent phenomena using quantum simulators will allow the experimental investigations of them in greater detail, deepening our understanding of quantum phases and phase transitions. The second half of the research activities introduces a new perspective to study quantum matter using the language of quantum information theory. Specifically, the research team will develop quantum and classical algorithms to efficiently extract important information such as the phase of quantum matter from experimental data and investigate the fundamental limitations in computational power of these new algorithms. This will provide new ways to characterize the properties of quantum matter such as the computational hardness of distinguishing two different phases. Successful outcomes will establish a rigorous connection between different disciplines of physical sciences such as renormalization group in theoretical physics and error corrections information theory. This award is jointly supported through funds contributed by the Division of Materials Research and the Physics Division within the Mathematical and Physical Sciences Directorate. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.