Quantum interference of topological states of light

Abstract

Topological insulators are materials that have a gapped bulk energy spectrum, but contain protected in-gap states appearing at their surface. These states exhibit remarkable properties such as unidirectional propagation and robustness to noise that offer an opportunity to improve the performance and scalability of quantum technologies. For quantum applications, it is essential that the topological states are indistinguishable. Here we report high-visibility quantum interference of single photon topological states in an integrated photonic circuit. Two topological boundary-states, initially at opposite edges of a coupled waveguide array, are brought into proximity, where they interfere and undergo a beamsplitter operation. We observe $93.1\pm 2.8\%$ visibility Hong-Ou-Mandel (HOM) interference, a hallmark non-classical effect that is at the heart of linear optics-based quantum computation. Our work shows that it is feasible to generate and control highly indistinguishable single photon topological states, opening pathways to enhanced photonic quantum technology with topological properties, and to study quantum effects in topological materials.

References in corpus (9)

• Topological Photonics
• Photonic quantum technologies
• Silica-on-Silicon Waveguide Quantum Circuits
• Quantum walks of correlated particles
• Photonic topological pumping through the edges of a dynamical four-dimensional quantum Hall system
• Observation of Topological Phase Transitions in Photonic Quasicrystals
• Topological Pumping over a Photonic Fibonacci Quasicrystal
• Multimode quantum interference of photons in multiport integrated devices
• High-fidelity operation of quantum photonic circuits

Cited by in corpus (11)

• Visualization of higher-order topological insulating phases in two-dimensional dielectric photonic crystals
• Low-threshold topological nanolasers based on second-order corner state
• Femtosecond laser micromachining for integrated quantum photonics
• Cavity Quantum Electrodynamics with Second-Order Topological Corner State
• Experimental observation of inter-orbital coupling
• Biphoton entanglement of topologically-distinct modes
• Observing 0D subwavelength-localized modes at ~100 THz protected by weak topology
• Topologically Protected Quantum Entanglement
• Sensing electrons during an adiabatic coherent transport passage
• Asymmetric topological pumping in nonparaxial photonics
• Hong-Ou-Mandel interference on a real beam splitter