2016/05/31 by Jakob Scharlau, Markus P. Mueller · 1 citation
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Bounded function #Control and Stability of Dynamical Systems #Degenerate energy levels #Dimension (graph theory) #Hamiltonian (control theory) #Lemma (botany) #Quantum #Quantum many-body systems #Quantum system #Quantum thermodynamics #Second law of thermodynamics #quant-ph
paper · pdf · doi:10.22331/q-2018-02-22-54
published as Quantum 2, 54 (2018) · 15+4 pages, 6 figures. Version accepted for publication in Quantum
openalex created_date 2016/06/24 · arxiv created 2018/02/10 · openalex publication_date 2018/02/22 · arxiv updated 2018/02/27 · openalex updated_date 2026/08/05
Interactions of quantum systems with their environment play a crucial role in resource-theoretic approaches to thermodynamics in the microscopic regime. Here, we analyze the possible state transitions in the presence of "small" heat baths of bounded dimension and energy. We show that for operations on quantum systems with fully degenerate Hamiltonian (noisy operations), all possible state transitions can be realized exactly with a bath that is of the same size as the system or smaller, which proves a quantum version of Horn's lemma as conjectured by Bengtsson and Zyczkowski. On the other hand, if the system's Hamiltonian is not fully degenerate (thermal operations), we show that some possible transitions can only be performed with a heat bath that is unbounded in size and energy, which is an instance of the third law of thermodynamics. In both cases, we prove that quantum operations yield an advantage over classical ones for any given finite heat bath, by allowing a larger and more physically realistic set of state transitions.