Speaker: Stefano Scali
Affiliation: Fujitsu Research of Europe
Date: Tuesday, 4 November 2025 at 12:00
Location: Online seminar
Quantum phase estimation (QPE) is a cornerstone algorithm for extracting Hamiltonian eigenvalues, but its standard form targets individual eigenstates and requires carefully prepared coherent inputs. To overcome these limitations, we adopt an ensemble-based formulation of QPE that estimates the density of states (DOS) of the Hamiltonian generator of the evolution. This approach, which we refer to as DOS-QPE, builds on a prior formulation introduced by one of the authors. In this talk, we present DOS-QPE as a circuit primitive, extending it with symmetry-adapted input ensembles and spectrum reconstruction via quadratic programs. This variant of QPE enables natural access to thermodynamic properties, symmetry-resolved spectral functions, and features relevant to quantum many-body systems with potential for early fault-tolerant quantum simulations in spectroscopy, electronic structure, and nuclear theory.