Materials Beyond Hamiltonian Limits -- Quantum Measurement as a Resource for Material Design

TL;DR

This paper explores how incorporating quantum measurement into electron dynamics enables the design of novel materials with functionalities beyond traditional Hamiltonian-based theories, including nonreciprocal transport and energy conversion.

Contribution

It introduces the concept of unitary-projective dynamics in material design, expanding the scope of quantum materials beyond Hamiltonian limits.

Findings

Demonstrates nonreciprocal single-electron transmission

Identifies a new category of magnetism in materials

Proposes energy harvesting platforms exceeding Carnot efficiency

Abstract

Recent studies have identified materials and devices whose behavior lies beyond the scope of conventional electronic-structure theory. Such theories are formulated entirely in terms of Hamiltonian evolution and therefore describe only unitary dynamics and thus only a restricted class of quantum systems. In contrast, electron systems that incorporate quantum measurement as an intrinsic dynamical element undergo Hamiltonian evolution interleaved with projection-induced state updates. This unitary-projective dynamics breaks constraints imposed by purely unitary evolution and permits stochastic population transfer between symmetry-related transport channels, thereby enabling fundamentally new material functionalities. This insight motivates the deliberate design of materials and devices that harness unitary-projective dynamics. This article explores the foundations of unitary-projective electron dynamics and charts the resulting landscape of quantum materials and their functionalities. Model calculations demonstrate passive mesoscopic structures with intrinsic nonreciprocal single-electron transmission, materials exhibiting a novel category of magnetism, and possible platforms for energy harvesting and conversion with efficiencies that exceed the standard Carnot limit.