Roadmap on all-optical processing

Abstract

The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which researchers operate, trying to find solutions to their specific needs by different approaches; although the challenges can be substantially different, they are typically addressed using knowledge and technological platforms that are shared across the whole field. This significant know-how can also benefit other scientific communities, providing lateral solutions to their problems, as well as leading to novel applications. The aim of this Roadmap is to provide a broad view of the state-of-the-art in this lively scientific research field and to discuss the advances required to tackle emerging challenges, thanks to contributions authored by experts affiliated to both academic institutions and high-tech industries. The Roadmap is organized so as to put side by side contributions on different aspects of optical processing, aiming to enhance the cross-contamination of ideas between scientists working in three different fields of photonics: optical gates and logical units, high bit-rate signal processing and optical quantum computing. The ultimate intent of this paper is to provide guidance for young scientists as well as providing research-funding institutions and stake holders with a comprehensive overview of perspectives and opportunities offered by this research field.

Optical Injection Locking: From Principle to Applications

“…However, the use of DSP may be undesirable in midspan regeneration, in which the signal is further transmitted on an optical carrier and it is often simply not possible to use it, e.g., in quantum optics. The use of DSP and ADC also increase power consumption and latency, which is highly-undesirable in many applications such as high-frequency trading, 5G mobile communications [98], and low latency coherent data center interconnection [99], [100]. In these areas, phase locking of the local oscillator to the incoming signal in the optical domain could be beneficial to coherent detection.…”

Connecting heterogeneous quantum networks by hybrid entanglement swapping

“…Here, |cat + ⟩ and |cat − ⟩ denote, respectively, the even and odd optical Schrödinger cat states (8) forming the basis of our CV qubit space, corresponding to superpositions of coherent states of amplitude a ≈ 0.9. The single-mode squeezed vacuum and the photon-subtracted squeezed vacuum states generated by the OPO can concurrently reach fidelities above 90% with these states at moderate squeezing levels of about 5 dB.…”

“…Several experiments have spearheaded the development of the hybrid quantum optics paradigm (6)(7)(8). The first realizations from a decade ago consisted in combining the DV and CV toolboxes to generate non-Gaussian states, such as optical Schrödinger cat states starting from Gaussian squeezed light (9)(10)(11).…”

Hybrid Rabi interactions with traveling states of light

“…Examples are quantum teleportation of a DV using CV protocol [14] or the teleportation of CV qubit to qubit [15], quantum repeater using hybrid protocol [76] or building on-chip integrated circuits [77]. Hybrid optical states have been generated experimentally to entangle the DV and CV [16][17][18][19][78][79][80][81][82][83][84]. Therefore, a natural question arises about whether and up to what extent we can induce the nonlinear effects of RI all-optically.…”