Zacharie Van Herstraeten

Quantum light through the lens of information theory

Light is a unique physical system that naturally exhibits the features of quantum mechanics—interference, entanglement, and other nonclassical correlations—while serving as a central platform for quantum technologies, from optical communications to photonic quantum computing. The quantum phase space offers a privileged setting for continuous-variable systems such as light, where statistical and wave-like aspects unfold within a unified geometric framework that makes quantum behavior tangible. Information theory extends this perspective by quantifying uncertainty, coherence, and correlations, bringing conceptual clarity and operational precision to our understanding of quantum phenomena.

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My research themes

Across this broad landscape, I’m drawn to the phase-space picture to explore how quantum resources and nonclassical signatures emerge in continuous-variable systems. My research develops along three interconnected directions:

Physicality constraints in phase space. In phase-space representations, determining whether a quasiprobability distribution represents a physically valid quantum state is often nontrivial, typically relying on abstract mathematical conditions. This direction aims to identify geometric and structural constraints—sharpening and extending uncertainty relations—to uncover deeper principles governing physicality within phase space.
Keywords: phase-space theory · uncertainty relations · positivity conditions

Entropic measures of nonclassicality. Intrinsically nonclassical quantum behavior often relies on a combination of resources whose precise roles are difficult to isolate. This direction seeks to define meaningful, operational measures of quantumness—sometimes inspired by resource-theoretic ideas—and to explore entropic approaches, possibly within phase space, as an insightful way to capture the richness and subtlety of quantum behavior.
Keywords: resource theories · majorization · generalized entropies

Information flow in optical interactions. Understanding how information propagates through bosonic channels remains a central question in quantum communication, particularly beyond the well-studied Gaussian regime. Focusing on simple yet expressive optical components such as the beam splitter, this direction aims to bridge the phase-space and operator representations to clarify the fundamental mechanisms of quantum information flow.
Keywords: channel capacity · non-Gaussian attenuator · minimum output entropy

If you’d like to learn more, you can browse my publications and my CV.