Quantum walks have attracted significant attention due to the possibility to propagate and reshape large-scale photon entanglement based on the superposition of possible photon paths. Entangling photons brings the promise of secure communication and ultra-fast quantum computing. Another phenomenon called optical nonlinearity allows interaction between electro-magnetic waves through matter. Bringing the concepts of quantum walks and optical nonlinearity together, and integrating them on a chip, opens a way to efficiently generate entangled photons and tune the entanglement. In this talk we will show the first experiments and theoretical studies featuring such tunable integrated sources.
Quantum walks have attracted significant attention due to the possibility to propagate and reshape large-scale photon entanglement based on the superposition of possible photon paths. Entangling photons brings the promise of secure communication and ultra-fast quantum computing. Another phenomenon called optical nonlinearity allows interaction between electro-magnetic waves through matter. Bringing the concepts of quantum walks and optical nonlinearity together, and integrating them on a chip, opens a way to efficiently generate entangled photons and tune the entanglement. In this talk we will show the first experiments and theoretical studies featuring such tunable integrated sources.
Photon entanglement has a range of applications from secure communication to the tests of quantum mechanics. Utilizing optical nonlinearity for the generation of entangled photons remains the most widely used approach due to its quality and simplicity. The on-chip integration of entangled light sources has enabled the increase of complexity and enhancement of stability compared to bulk optical implementations. Entanglement over different optical paths is uniquely suited for photonic chips, since waveguides are typically optimized for particular wavelength and polarization, making polarization- and frequency-entanglement less practical. In this review we focus on the latest developments in the field of on-chip nonlinear path-entangled photon sources. We provide a review of recent implementations and compare various approaches to tunability, including thermo-optical, electro-optical and all-optical tuning. We also discuss a range of important technical issues, in particular the on-chip separation of the pump and generated entangled photons. Finally, we review different quality control methods, including on-chip quantum tomography and recently discovered classical-quantum analogy that allows to characterize entangled photon sources by performing simple nonlinear measurements in the classical regime.
Integrated optical platforms enable the realization of complex quantum photonic circuits for a variety of applications including quantum simulations, computations, and communications. The development of on-chip integrated photon sources, providing photon quantum states with on-demand tunability, is currently an important \nresearch area. A flexible approach for on-chip generation of entangled photons is based on spontaneous nonlinear \nfrequency conversion, with possibilities to integrate several photon-pair sources [1] and realize subsequent post \nprocessing using thermo-optically or electro-optically controlled interference [2, 3]. However, deterministic postprocessing can only provide a limited set of output states, whereas quantum gates with probabilistic operation are \nneeded to generate arbitrary two-photon states [4].
Of the various approaches to quantum computing, photons are appealing for their low-noise properties and ease of manipulation at the single photon level; while the challenge of entangling interactions between photons can be met via measurement induced non-linearities. However, the real excitement with this architecture is the promise of ultimate manufacturability: All of the components---inc. sources, detectors, filters, switches, delay lines---have been implemented on chip, and increasingly sophisticated integration of these components is being achieved. We will discuss the opportunities and challenges of a fully integrated photonic quantum computer.
The ability to generate complex optical photon states involving entanglement between multiple optical modes is not only critical to advancing our understanding of quantum mechanics but will play a key role in generating many applications in quantum technologies. These include quantum communications, computation, imaging, microscopy and many other novel technologies that are constantly being proposed. However, approaches to generating parallel multiple, customisable bi- and multi-entangled quantum bits (qubits) on a chip are still in the early stages of development. Here, we review recent advances in the realisation of integrated sources of photonic quantum states, focusing on approaches based on nonlinear optics that are compatible with contemporary optical fibre telecommunications and quantum memory platforms as well as with chip-scale semiconductor technology. These new and exciting platforms hold the promise of compact, low-cost, scalable and practical implementations of sources for the generation and manipulation of complex quantum optical states on a chip, which will play a major role in bringing quantum technologies out of the laboratory and into the real world.
Integrated quantum photonic system has become a promising candidate for next-generation quantum optical system. Thanks to the scalability and strong light-matter interactions, such nanophotonic systems can realize compactness, large-scale integration, stability, and novel optical functionalities simultaneously. In this talk, I will introduce our experimental works in the fields of the integrated lithium niobate photonics. First, we demonstrate a set of nonlinear photon-pair generations for the nonlinear quantum photonic sources. Next, I will show our works on lithium-niobate integrated quantum photonic circuits for the application in quantum communications and variational quantum simulations.
A key challenge in today’s quantum science is the realization of large-scale complex non-classical systems to enable e.g. ultra-secure communications, quantum-enhanced measurements, and computations faster than classical approaches. Optical frequency combs represent a powerful approach towards this, since they provide a very high number of temporal and frequency modes which can result in large-scale quantum systems. Here, we discuss the recent progress on the realization of integrated quantum frequency combs and reveal how their use in combination with on-chip and fiber-optic telecommunications components can enable quantum state control with new functionalities, yielding unprecedented capability.