Scalable techniques for electronic control of programmable photonic circuits

Developing hardware for high-dimensional unitary operators plays a vital role in implementing quantum computations and deep learning accelerations. Programmable photonic circuits are singularly promising candidates for universal unitaries owing to intrinsic unitarity, ultrafast tunability and energy efficiency of photonic platforms. Nonetheless, when the scale of a photonic circuit increases, the effects of noise on the fidelity of quantum operators and deep learning weight matrices become more severe. Here we demonstrate a nontrivial stochastic nature of large-scale programmable photonic circuits—heavy-tailed distributions of rotation operators—that enables the development of high-fidelity universal unitaries through designed pruning of superfluous rotations. The power law and the Pareto principle for the conventional architecture of programmable photonic circuits are revealed with the presence of hub phase shifters, allowing for the application of network pruning to the design of photonic hardware. For the Clements design of programmable photonic circuits, we extract a universal architecture for pruning random unitary matrices and prove that “the bad is sometimes better to be removed” to achieve high fidelity and energy efficiency. This result lowers the hurdle for high fidelity in large-scale quantum computing and photonic deep learning accelerators.

Programmable photonic circuits (PPCs) are recognized as building blocks for photonic neuromorphic devices and reconfigurable photonic neural networks (PNNs). While traditional PPCs are primarily made of inorganic materials, polymeric materials offer advantages such as mechanical flexibility and a rapid fabrication process at low cost. Here, we demonstrate a fully polymeric PPC constructed only from polydimethylsiloxane (PDMS) doped with the organic dye Rhodamine123. We initially fabricated a Y‐shaped all‐optical logic gate from PDMS and demonstrated its functionality as both an OR and NAND gate. Following this, we fabricated three distinct shapes of PDMS photonic structures and evaluated their performance by injecting amplitude‐modulated optical signals of varying wavelengths and measuring their resulting output signals. By doping one of the PDMS structures (in the shape of a hexagonal mesh) with Rhodamine123 at specific locations and heating the entire structure, we managed to control the intensities of the output optical signals, indicating that temperature serves as a programmable parameter that may regulate the ‘weights’ in a polymer‐organic PNN device. This dual control via doping concentration and temperature introduces a novel method for PPCs made of organic materials. Our findings suggest a promising route toward flexible, low‐cost, and biocompatible photonic neuromorphic hardware leveraging polymer‐organic platforms.

Programmable photonic circuits are versatile platforms that route light through multiple interference paths using reconfigurable optoelectronic elements to perform complex discrete linear operations. These circuits offer the potential for high-speed and low-power photonic information processing in various applications. The mainstream research on programmable photonics has focused on implementing linear operations on discrete signals encoded in the modal amplitudes of an array of spatially separated single-mode waveguides. However, many photonic device applications require simultaneous transformations in the space-frequency domain, where information is encoded in both the spatial modes of waveguides and their spectral content. Here, we experimentally demonstrate linear space-frequency transformations using a four-port programmable silicon photonic circuit with an alternating architecture. This design leverages the limited dispersion of coupled waveguide arrays to enable linear operations with reconfigurable frequency-dependent matrix elements. We utilize this device to perform wavelength demultiplexing and filtering. This architecture platform can pave the way for versatile devices with applications ranging from wavelength routing to programmable dispersion control.

Programmable integrated photonics has emerged as a powerful platform for implementing diverse optical functions on a single chip through software-driven reconfiguration. At the core of these processors, photonic waveguide meshes enable flexible light routing and manipulation. However, recirculating waveguide meshes are fundamentally limited by the fixed dimensions of their unit cells, constraining their spectral and temporal resolution. These limitations hinder broadband signal processing and high-precision delay-line applications. Here, we introduce the concept of non-uniform programmable waveguide meshes by incorporating defect cells into an otherwise uniform hexagonal architecture. These defect cells preserve an external hexagonal perimeter for seamless integration while embedding smaller internal subcells that modify the spectral response via the Vernier effect. By coupling cells with different optical path lengths, we achieve a free spectral range multiplication of up to tenfold, reaching 133 GHz—surpassing the capabilities of conventional silicon ring resonators. Additionally, we demonstrate a dramatic reduction in sampling times from 75 ps to 7.5 ps, enabling ultra-fast optical signal processing and high-precision delay tuning. This approach unlocks new degrees of freedom in programmable photonic circuits, offering enhanced spectral and temporal tunability. Beyond broadband signal processing, it paves the way for advanced applications in topological photonics, quantum information processing, and high-speed optical computing.

Ultra-low-power consumption and high-speed integrated switches are highly desirable for future data centers and high-performance optical computers. In this study, we proposed an ultra-low-power consumption silicon electro-optic switch based on photonic crystal nanobeam cavities on a foundry platform. The proposed switch showed an ultra-low static-tuning power of 0.10 mW and a calculated dynamic switching power of 6.34 fJ/bit, with a compact footprint of 18 μm × 200 μm. Additionally, a 136-Gb/s four-level pulse amplitude modulation signal transmission experiment was carried out to verify the capability of the proposed electro-optic switch to support high-speed data transmission. The proposed device has the lowest static-tuning power consumption among silicon electro-optic switches and the highest data transmission rate. The results demonstrate the potential applications of this switch in high-performance optical computers, data center interconnects, optical neural networks, and programmable photonic circuits.

Nanoscale optical functionalities show promise for unconventional computing, including neuromorphic and quantum information processing. Resistive switching devices with optical readability have drawn significant research interest for high-density non-volatile memory and unconventional computing. We proposed a multiwavelength nanophotonic circuit consisting of resistive switches based on Ag-SiO2-ITO on a silicon rib structure, with the capability to electrically remove any wavelength channel(s) at will. The device featured a four-layered structure with a SiO2 region positioned between an Ag top electrode and an ITO bottom electrode on p-Si, confining the hybrid plasmonic mode within the SiO2 region. The application of an external voltage caused the formation/rupture of conductive filaments in the SiO2 layer, affecting optical absorption through hybrid mode interactions. Experimental results showed a 27 dB extinction ratio for a 10 μm × 500 nm active device operated at ±2 V. Additionally, the circuit achieved multiwavelength functionality using identical sources and 2 × 1 couplers, enhancing reconfigurability. The higher work function of ITO helped in reducing the energy barrier for ion migration, overcoming the intrinsic resistance of the SiO2 layer. This engineered nanophotonic circuit, with its high extinction ratio, excellent retention, low-voltage operation, and rapid switching speed, is suitable for advanced memory devices, high-speed optical communication, neuromorphic and quantum computation, and programmable photonic circuits.

Energy storage systems are pivotal for maximising the utilisation of renewable energy sources for smart grid and microgrid systems. Among the ongoing advancements in energy storage systems, the power conditioning systems for energy storage systems represent an area that can be significantly improved by using advanced power electronics converter designs and control techniques. Normally, the battery, flywheel, ultracapacitor and superconducting magnetic energy storage are the types of energy storage systems that typically require power conditioning systems for efficient bidirectional power flows. Compared to the previous review papers, this paper critically reviews the power conditioning system configurations and control techniques from the perspective of energy storage system applications in the power systems. First, the power conditioning systems are categorised into DC bus power conditioning systems and AC bus power conditioning systems based on the output voltage types at the connected point. Next, the topologies and control configurations of popular power electronics are comparatively analysed to highlight their advantages and power system applications. Moreover, the control configurations are discussed in terms of the popular applications of energy storage systems, that is, power backup smoothing, frequency regulation, voltage regulation and power quality applications. In addition, the latest developments in the energy storage system such as multi‐functional energy storage system stacking, artificial intelligence for power conditioning system of energy storage systems and security of control of energy storage systems are critically analysed. Finally, the review is concluded by discussing industrial applications and future research trends for the power conditioning systems of energy storage systems.

Switched reluctance motor (SRM) is gaining prominence due to its simple and rugged construction, absence of permanent magnets, low cost, fault-tolerant capability and developments in power electronics. These benefits with SRM are counteracted by the presence of torque ripple, high acoustic noise, need for rotor position information and complex control due to nonlinear behavior. Torque ripple can be reduced by improving the magnetic design of the motor and by using sophisticated electronic control techniques. This paper provides an overview of various control techniques available in the literature for torque ripple minimization in SRM and their limitations.

The implementation of large-scale universal quantum computation represents a challenging and ambitious task on the road to quantum processing of information. In recent years, an intermediate approach has been pursued to demonstrate quantum computational advantage via non-universal computational models. A relevant example for photonic platforms has been provided by the Boson Sampling paradigm and its variants, which are known to be computationally hard while requiring at the same time only the manipulation of the generated photonic resources via linear optics and detection. Beside quantum computational advantage demonstrations, a promising direction towards possibly useful applications can be found in the field of quantum machine learning, considering the currently almost unexplored intermediate scenario between non-adaptive linear optics and universal photonic quantum computation. Here, we report the experimental implementation of quantum machine learning protocols by adding adaptivity via post-selection to a Boson Sampling platform based on universal programmable photonic circuits fabricated via femtosecond laser writing. Our experimental results demonstrate that Adaptive Boson Sampling is a viable route towards dimension-enhanced quantum machine learning with linear optical devices.

This work presents the design of a compact, bend-less Mach-Zehnder Interferometer (MZI) for high-density programmable photonic circuits, utilizing ferroelectric barium titanate (BaTiO3 or BTO) as the electro-optically active material. Unlike the conventional MZI, which uses waveguide bends to isolate or decouple waveguides in the phase shifter section, the proposed design removes the need for bends by introducing a controlled mode mismatch between the waveguides. We utilize one of the high Pockels coefficients of BTO (r<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> = 342 pm/V) at a low voltage of 4.5 V to realize the required mode mismatch for decoupling waveguides in the phase shifter. Full-vector 3D COMSOL simulations are performed for the complete design using a push-pull configuration in the phase shifter, resulting in a low V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">π</inf> • L product of 0.276 V • cm.

Introduction. Currently, the direct torque control is very popular in industry and is of great interest to scientists in the variable speed drive of asynchronous machines. This technique provides decoupling between torque control and flux without the need to use pulse width modulation or coordinate transformation. Nevertheless, this command presents two major importunities: the switching frequency is highly variable on the one hand, and on the other hand, the amplitude of the torque and stator flux ripples remain poorly controlled throughout the considered operating speed range. The novelty of this article proposes improvements in performance of direct torque control of asynchronous machines by development of a fuzzy direct torque control algorithm. This latter makes it possible to provide solutions to the major problems of this control technique, namely: torque ripples, flux ripples, and failure to control switching frequency. Purpose. The emergence of this method has given rise to various works whose objective is to show its performance, or to provide solutions to its limitations. Indeed, this work consists in validation of a fuzzy direct torque control architecture implemented on the ML402 development kit (based on the Xilinx Virtex-4 type field programmable gate array circuit), through hardware description language (VHDL) and Xilinx generator system. The obtained results showed the robustness of the control and sensorless in front of load and parameters variation of induction motor control. The research directions of the model were determined for the subsequent implementation of results with simulation samples.

This paper describes a novel approach to operate a pseudo direct drive (PDD) permanent-magnet machine with a single sensor on the low-speed rotor (LSR). Due to the magnetic coupling between its two rotors, the PDD machine exhibits torsional oscillation when conventional control techniques are employed. While full state feedback (SFBK) control can effectively suppress torsional oscillation, the need for a position sensor mounted on the high-speed rotor (HSR) for electronic commutation imposes great constraints on the PDD mechanical design. A novel technique has been developed in order to control the PDD machine using a single sensor mounted on the LSR, whereas the position and speed of the HSR required for electronic commutation and SFBK control are estimated with an observer. Both the SFBK controller and observer are optimally designed using the genetic algorithm against a defined set of criteria and constraints. The proposed control technique has been validated by experiments on a prototype PDD system.

The integration of distributed energy resources (DER) generation units based on renewable energy systems into the power system is going on at an unprecedented rate in both bulk power systems and distribution systems globally. However, as the penetration of DER renewables in the power system increases, the system inertia will decline leading to stability issues. As a result, improved converter control methods are required to ensure the high penetration of DERs into the existing power system will not jeopardize the future smart grid. Given that the synchronous generator (SG) has been the bedrock of stable power system operation for over a century, it is desirable for these converter control schemes to emulate the dynamics of the synchronous generator. This idea connotes the virtual synchronous generator (VSG) concept. This paper highlights key findings from recent publications with regard to the VSG concept, by identifying strengths and weaknesses. The inadequacies in some of these literatures are then addressed. A study on the synchronous generator is presented in order to better understand how it controls essential grid parameters. A control technique for an inverter to emulate the SG’s droop control and inertia property is then proposed. For performance evaluation, this control technique is simulated in MATLAB/Simulink using closed-loop control of the inverter.

A photonic circuit is generally described as a structure in which light propagates by unitary exchange and transfers reversibly between channels. In contrast, the term ‘diffusive’ is more akin to a chaotic propagation in scattering media, where light is driven out of coherence towards a thermal mixture. Based on the dynamics of open quantum systems, the combination of these two opposites can result in novel techniques for coherent light control. The crucial feature of these photonic structures is dissipative coupling between modes, via an interaction with a common reservoir. Here, we demonstrate experimentally that such systems can perform optical equalisation to smooth multimode light, or act as a distributor, guiding it into selected channels. Quantum thermodynamically, these systems can act as catalytic coherent reservoirs by performing perfect non-Landauer erasure. For lattice structures, localised stationary states can be supported in the continuum, similar to compacton-like states in conventional flat-band lattices.

We realize and investigate ionic liquid gated field-effect transistors (FETs) on large-area MoS2 monolayers grown by chemical vapor deposition (CVD). Under electron accumulation, the performance of these devices is comparable to that of FETs based on exfoliated flakes. FETs on CVD-grown material, however, exhibit clear ambipolar transport, which for MoS2 monolayers had not been reported previously. We exploit this property to estimate the bandgap Δ of monolayer MoS2 directly from the device transfer curves and find Δ ≈ 2.4-2.7 eV. In the ambipolar injection regime, we observe electroluminescence due to exciton recombination in MoS2, originating from the region close to the hole-injecting contact. Both the observed transport properties and the behavior of the electroluminescence can be consistently understood as due to the presence of defect states at an energy of 250-300 meV above the top of the valence band, acting as deep traps for holes. Our results are of technological relevance, as they show that devices with useful optoelectronic functionality can be realized on large-area MoS2 monolayers produced by controllable and scalable techniques.