A Tale of Two Disciplines: Non-Abelian Eigenstate Thermalization Hypothesis
Abstract: Why do chaotic quantum many-body systems thermalize internally? The eigenstate thermalization hypothesis (ETH) explains why if the Hamiltonian lacks degeneracies. If the Hamiltonian conserves one quantity ("charge"), the ETH implies thermalization within an eigenspace of the charge—in a microcanonical subspace. However, quantum systems can have charges that fail to commute with each other and so share no eigenbasis; microcanonical subspaces may not exist. Worse, the Hamiltonian will have degeneracies, so the ETH need not imply thermalization.
Nicole Yunger Halpern
Nicole will be a NIST physicist, JQI affiliate, QuICS Fellow, and Adjunct Assistant Professor of Physics and IPST, beginning in fall 2021. She re-envisions 19th-century thermodynamics for the 21st century, using the mathematical toolkit of quantum information (QI) theory. She then applies QI thermodynamics as a lens through which to view the rest of science, gaining new perspectives on atomic, molecular, and optical physics; condensed matter; chemistry; high-energy physics; and biophysics.
Nicole Yunger Halpern Ponders Quantum Mechanics, Thermodynamics, and Everything Else
There is a well-known saying, of disputed origin, that dissuades students and even working physicists from thinking too deeply about the meaning behind quantum physics. “Shut up and calculate,” it goes.