Suppression law of quantum states in a 3D photonic fast Fourier transform chip

The identification of phenomena able to pinpoint quantum interference is attracting large interest. Indeed, a generalization of the Hong-Ou-Mandel effect valid for any number of photons and optical modes would represent an important leap ahead both from a fundamental perspective and for practical applications, such as certification of photonic quantum devices, whose computational speedup is expected to depend critically on multi-particle interference. Quantum distinctive features have been predicted for many particles injected into multimode interferometers implementing the Fourier transform over the optical modes. Here we develop a scalable approach for the implementation of the fast Fourier transform algorithm using three-dimensional photonic integrated interferometers, fabricated via femtosecond laser writing technique. We observe the suppression law for a large number of output states with four- and eight-mode optical circuits: the experimental results demonstrate genuine quantum interference between the injected photons, thus offering a powerful tool for diagnostic of photonic platforms

Photonic quantum information processing: a review

Photonic quantum technologies represent a promising platform for several applications, ranging from long-distance communications to the simulation of complex phenomena. Indeed, the advantages offered by single photons do make them the candidate of choice for carrying quantum information in a broad variety of areas with a versatile approach. Furthermore, recent technological advances are now enabling first concrete applications of photonic quantum information processing. The goal of this manuscript is to provide the reader with a comprehensive review of the state of the art in this active field, with a due balance between theoretical, experimental and technological results. When more convenient, we will present significant achievements in tables or in schematic figures, in order to convey a global perspective of the several horizons that fall under the name of photonic quantum information.Comment: 36 pages, 6 figures, 634 references. Updated version with minor changes and extended bibliograph

Experimental generalized quantum suppression law in Sylvester interferometers

Photonic interference is a key quantum resource for optical quantum computation, and in particular for so-called boson sampling devices. In interferometers with certain symmetries, genuine multiphoton quantum interference effectively suppresses certain sets of events, as in the original Hong-Ou-Mandel effect. Recently, it was shown that some classical and semi-classical models could be ruled out by identifying such suppressions in Fourier interferometers. Here we propose a suppression law suitable for random-input experiments in multimode Sylvester interferometers, and verify it experimentally using 4- and 8-mode integrated interferometers. The observed suppression occurs for a much larger fraction of input-output combinations than what is observed in Fourier interferometers of the same size, and could be relevant to certification of boson sampling machines and other experiments relying on bosonic interference, such as quantum simulation and quantum metrology

Trigonospermum hintoniorum B.L. Turner

The difficulty of validating large-scale quantum devices, such as boson samplers, poses a major challenge for any research program that aims to show quantum advantages over classical hardware. Towards this aim, we propose a novel data-driven approach, wherein models are trained to identify common pathologies using unsupervised machine-learning methods. We illustrate this idea by training a classifier that exploits K-means clustering to distinguish between boson samplers that use indistinguishable photons from those that do not. We tune the model on numerical simulations of small-scale boson samplers and then validate the pattern-recognition technique on larger numerical simulations as well as on photonic chips in both traditional boson-sampling and scatter-shot experiments. The effectiveness of such a method relies on particle-type-dependent internal correlations present in the output distributions. This approach performs substantially better on the test data than previous methods and underscores the ability to further generalize its operation beyond the scope of the examples that it was trained on

Interfacing scalable photonic platforms: Solid-state based multi-photon interference in a reconfigurable glass chip

Scaling-up optical quantum technologies requires a combination of highly efficient multi-photon sources and integrated waveguide components. Here, we interface these scalable platforms, demonstrating high-rate three-photon interference with a quantum dot based multi-photon source and a reconfigurable photonic chip on glass. We actively demultiplex the temporal train of single photons obtained from a quantum emitter to generate a 3.8 × 103 s−1 three-photon source, which is then sent to the input of a tunable tritter circuit, demonstrating the on-chip quantum interference of three indistinguishable single photons. We show via pseudo number-resolving photon detection characterizing the output distribution that this first combination of scalable sources and reconfigurable photonic circuits compares favorably in performance with respect to previous implementations. Our detailed loss-budget shows that merging solid-state multi-photon sources and reconfigurable photonic chips could allow 10-photon experiments on chip at ∼40 s−1 rate in a foreseeable future

Interfacing scalable photonic platforms: solid-state based multi-photon interference in a reconfigurable glass chip

International audienc

Experimental statistical signature of many-body quantum interference

Multi-particle interference is an essential ingredient for fundamental quantum mechanics phenomena and for quantum information processing to provide a computational advantage, as recently emphasized by boson sampling experiments. Hence, developing a reliable and efficient technique to witness its presence is pivotal in achieving the practical implementation of quantum technologies. Here, we experimentally identify genuine many-body quantum interference via a recent efficient protocol, which exploits statistical signatures at the output of a multimode quantum device. We successfully apply the test to validate three-photon experiments in an integrated photonic circuit, providing an extensive analysis on the resources required to perform it. Moreover, drawing upon established techniques of machine learning, we show how such tools help to identify the-a priori unknown-optimal features to witness these signatures. Our results provide evidence on the efficacy and feasibility of the method, paving the way for its adoption in large-scale implementations