English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We obtain a modified version of the Onsager regression relation for theexpectation values of quantum-mechanical operators in pure quantum states ofisolated many-body quantum systems. We use the insights gained from thisrelation to show that high-temperature time correlation functions in many-bodyquantum systems can be controllably computed without complete diagonalizationof the Hamiltonians, using instead the direct integration of the Schroedingerequation for randomly sampled pure states. This method is also applicable toquantum quenches and other situations describable by time-dependent many-bodyHamiltonians. The method implies exponential reduction of the computer memoryrequirement in comparison with the complete diagonalization. We illustrate themethod by numerically computing infinite-temperature correlation functions fortranslationally invariant Heisenberg chains of up to 29 spins 1/2. Thereby, wealso test the spin diffusion hypothesis and find it in a satisfactory agreementwith the numerical results. Both the derivation of the modified regressionrelation and the justification of the computational method are based on thenotion of quantum typicality.

Regression relation for pure quantum states and its implications for efficient computing