Local Minima in Quantum Systems

Explore the computational challenges and implications of finding local minima in quantum systems in this 46-minute lecture by Robert Huang from Google. Delve into the complexities of ground state discovery in quantum many-body systems and understand why this process is difficult for both classical and quantum computers. Examine how Nature's cooling process in low-temperature thermal baths leads to local energy minima rather than true ground states. Investigate the computational hardness of finding local minima for classical computers, even when the task is limited to outputting a single-qubit observable. Contrast this with the efficiency of quantum computers in locating local minima using a thermal gradient descent algorithm that mimics natural cooling processes. Analyze a family of two-dimensional Hamiltonians where all local minima are global minima, and explore the implications for the relative power of quantum versus classical computation. Gain insights into quantum complexity, quantum PCP, area laws, and their connections to quantum gravity.