Quantum Science and Engineering Seminar - Rahul Trivedi

Quantum computers offer a promising approach to simulating many-body physics. While a comprehensive set of algorithms for many-body problems has been developed for fully fault-tolerant quantum computers, current and next-generation platforms are expected to operate either directly on noisy physical qubits or with only moderate error correction. This raises a fundamental theoretical question: How well can quantum many-body problems be solved on noisy analog or digital quantum simulators?
In this talk, I will describe our efforts to understand the noise robustness of quantum simulators and to analyze meaningful notions of quantum advantage in simulating quantum many-body physics. In particular, I will show that, due to quasi-locality properties present in physically relevant models, their quantum simulation avoids a worst-case proliferation of errors. This holds both when the target model is natively implementable on the simulator and when nontrivial problem-to-simulator mappings are required, such as Trotterization, Floquet–Magnus expansions, and perturbative expansions. Next, I will address the possibility of a quantum advantage for simulating many-body systems, that are noise-robust, both with respect to noise-rate scaling and system-size scaling, and connect this to the classical complexity of simulating geometrically local quantum circuits. I will conclude with an overview of some of our broader research activity in the field of many-body open quantum systems, both in connection to quantum information processing in the presence of noise as well as to further the fundamental physical understanding of these systems.