# Observation of Quantum Zeno blockade on Chip

## TL;DR

This paper reports the on-chip observation of quantum Zeno blockade, demonstrating interaction-free modulation of light at the single-photon level, which could advance scalable quantum information processing and nonlinear optics.

## Contribution

It presents the first on-chip demonstration of quantum Zeno blockade, enabling interaction-free light modulation suitable for quantum applications.

## Key findings

- Successful on-chip observation of quantum Zeno blockade.
- Verification of operation at the single-photon level.
- Potential for scalable quantum information processing.

## Abstract

When overlapping in an optical medium with nonlinear susceptibility, light waves can interact with each other, changing their phases, wavelengths, shapes, and so on. Such nonlinear effects, discovered over a half century ago, have given rise to a breadth of important applications. Applying to quantum-mechanical signals, however, they face fundamental challenges arising from the multimode nature of the interacting electromagnetic fields, such as phase noises and Raman scattering. Quantum Zeno blockade allows strong interaction of light waves without them physically overlapping, thus providing a viable solution for those challenges, as indicated in recent bulk-optics experiments. Here, we report on the observation of quantum Zeno blockade on chip, where a light wave is modulated by another in a distinct "interaction-free" manner. For quantum applications, we also verify its operations on a single-photon level. Our results promise a scalable platform for overcoming several grand challenges faced by nonlinear optics and quantum information processing, enabling, e.g., manipulation and interaction of quantum signals without decoherence.