In this work, we present a method for characterizing the transmission matrices of complex scattering media using a physics-informed, multi-plane neural network (MPNN) without the requirement of a known optical reference field. In contrast to previous techniques, our method is able to measure complete information about the transmission matrix, which is necessary for coherent control of light through a complex medium. Here, we design a neural network that describes the exact physical apparatus consisting of a trainable layer describing the unknown transmission matrix. We then employ randomized measurements to train the neural network which accurately recovers the transmission matrix of a commercial multi-mode fiber. We demonstrate how our method is significantly more accurate, and noise-robust than the standard method of phase-stepping holography and show how it can be generalized to characterize a cascade of transmission matrices. This work presents an essential tool for accurate light control through complex media, with applications ranging from classical optical networks, biomedical imaging, to quantum information processing.
Programmable optical circuits form a key part of quantum technologies today. As the size of such circuits is increased, maintaining precise control over every individual component becomes challenging. Here we show how embedding an optical circuit in the higher-dimensional space of a large mode-mixer allows us to forgo control over individual elements, while retaining a high degree of programmability over the circuit. Using this approach, we implement high-dimensional linear optical circuits within a commercial multi-mode fibre placed between controllable phase planes. We employ these circuits to manipulate high-dimensional entanglement in up to seven dimensions, demonstrating their application as fully programmable quantum gates. Furthermore, we show how these circuits turn the multi-mode fibre itself into a generalized multi-outcome measurement device, allowing us to both transport and certify entanglement. Finally, we show how a high circuit fidelity can be achieved with a low circuit depth by harnessing the resource of a high-dimensional mode-mixer. Our work serves as an alternative yet powerful approach for realizing precise control over high-dimensional quantum states of light.
Previous research demonstrated that two-soliton interactions can lead to nonreciprocal soliton amplification, a mechanism that can accumulate energy for rogue wave formation as soliton interactions increase. The question arises whether three or more soliton collisions can lead to amplification or chaotic behavior, akin to the three-body problem in particle physics. Through experiments and simulations using a photorefractive potassium-lithium-tantalate-niobate (KTN:Li) crystal, our study explores multiple soliton collisions with strong nonreciprocal energy exchange. Chaotic dynamics and intense wave formation are observed after a collinear three-soliton collision. However, when an additional dimension without broken inversion symmetry is introduced, the solitons consistently fuse into an intense wave instead of exhibiting chaos. This insight highlights the role of dimensionality and nonreciprocal energy exchange in determining soliton behavior and rogue wave formation. The study underscores the analogy between solitons and particles, linking chaotic behavior in three-body physics to the emergence of rogue waves.
The development of high-quality photonic sources of high-dimensional entanglement and techniques for their manipulation is crucial for the advancement of quantum technologies. We present an efficient technique for generating and characterizing high-dimensional spatially entangled two-photon states with a record quality, dimensionality, and measurement speed. We demonstrate how to precisely manipulate such states by tailoring reprogrammable optical circuits in complex scattering media consisting of off-the-shelf multimode fiber and spatial light modulation. Our techniques open a clear pathway for the adoption of high-dimensional quantum states of light in the high-capacity, noise-robust quantum networks of tomorrow.
The race to heuristically solve non-deterministic polynomial-time (NP) problems through efficient methods is ongoing. Recently, optics was demonstrated as a promising tool to find the ground state of a spin-glass Ising Hamiltonian, which represents an archetypal NP problem. However, achieving completely programmable spin couplings in these large-scale optical Ising simulators remains an open challenge. Here, by exploiting the knowledge of the transmission matrix of a random medium, we experimentally demonstrate the possibility of controlling the couplings of a fully connected Ising spin system. By further tailoring the input wavefront we showcase the possibility of modifying the Ising Hamiltonian both by accounting for an external magnetic field and by controlling the number of degenerate ground states and their properties and probabilities. Our results represent a relevant step toward the realisation of fully-programmable Ising machines on thin optical platforms, capable of solving complex spin-glass Hamiltonians on a large scale.
Spatial Ising Machines are simple optical acceleration devices enabling hard combinatorial optimization with millions of spins. We review our results, including noise acceleration and adiabatic evolution.
We review our results on Ising machines by spatial light modulation. We report on their performance in simulating spin glasses and solving combinatorial optimization problems. We discuss different annealing strategies and recent developments.
We apply concepts from machine learning to design topological one-dimensional systems. We also use tensorflow and related tools for designing quantum gates for multilevel qdits with random and unknown media.
We report on experiments concerning the realization of a large-scale Ising machine and the use of an optical neural network for detecting cancer morphodynamics in in-vitro tumor models.
Antibacterial items are one of the major queries from the medical community in the fight against medical infections. Indeed, bacteria are resistant and their multiplication and biofilm formation on devises are one of the major causes of infections. Finding antibacterial surfaces, which are biocompatible, cost-effective, not toxic, and spreadable over large and irregular surfaces, is not easy. However, we created an antibacterial cloak by laser printing of Graphene Oxide (GO) hydrogels by mimicking the Cancer Pagurus carapace. This surface provides up to 90% reduction of bacteria cells through a bacteriostatic and bactericidal effect. Indeed, Laser treating allows GO sheets gel to cut and wrap microorganisms. Our findings are confirmed by a theoretical active matter model. This new technology based on antibiotic-free biomimetic Graphene Oxide gels opens untrodden roads to the fight against infections in biomedical applications and chirurgical equipment.
In this paper we describe recent progress in the study of scale-free optical propagation in super-cooled nonergodic
ferroelectrics. Our experimental and theoretical findings indicate that a regime can be found in which
diffusion-driven photorefractive effects can fully annul the diffraction of focused laser beams. This demonstrates
that diffraction can be systematically eliminated from an optical system and not simply compensated, with
fundamental implications for optical imaging and microscopy. The effect transfers directly from the paraxial
regime into the non-paraxial regime described by the Helmholtz Equation, and suggests a means to achieve the
propagation of super-resolved optical images. The result is a nonlinear-based metamaterial, even though the
underlying nano-structuring of the ferroelectric is random and the effect is both non-absorptive and wavelengthindependent
for a wide spectrum.
The study of optical solitons and light filaments steering in liquid crystals requires utilization of particular
cells designed for top view investigation and realized with an input interface which enables both to control the
molecular director configuration and to prevent light scattering. Up to now, the director orientation imposed by
this additional interface has been only estimated by experimental observations. In this paper, we report on the
design and characterization of liquid crystal cells for investigation of optical spatial solitons as well as on a simple
model describing the configuration of the molecular director orientation under the anchoring action of multiple
interfaces. The model is based on the elastic continuum theory and only strong anchoring is considered for
boundary conditions. Controlling of the director orientation at the input interface, as well as in the bulk, allows
to obtain configurations that can produce distinct optical phenomena in a light beam propagating inside the cell.
For a particular director configuration, it is possible to produce two waves: the extraordinary and the ordinary
one. With a different director configuration, the extraordinary wave only is obtained, which propagates inside
the cell at an angle of more than 7° with respect to the impinging wave vector direction. Under this peculiar
configuration and by applying an external voltage, it is possible to have a good control of the propagation
direction of the optical spatial soliton.
We numerically investigate efficient frequency doubling of near infrared light in a coupled system of buried and surface waveguides obtained by Reverse Proton Exchange in z-cut Lithium Niobate. For a monomode TE surface guide at 1.32 micrometer and a highly multimode TM (buried) guide at 666 nm and exploiting the d31 nonlinear tensor element, for planar structures we calculated conversion efficiencies as high as 14% micrometer/W cm, with a weak dependence on temperature. Noticeably, this geometry features the physical separation of the harmonics at the output.
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