This PDF file contains the front matter associated with SPIE Proceedings Volume 11540, including the Title Page, Copyright information, and Table of Contents.

The UK is continuing its drive to commercialise Quantum Technology in Imaging, Sensing, Communications and Computing. In the first part of my talk I will give an overview of the work of QuantIC, the UK hub tasked with bringing quantum technology to bear on real world imaging challenges, across the industrial, scientific, security and consumer markets. In the second part of my talk I will feature some of my own group’s work on using quantum illumination to both increase image resolution and suppress background and detector noise. Pairs of photons that are quantum entangled with each other are correlated in many degrees of freedom, creation-time, energy, lateral position etc. Fundamentally this means that measuring one of the photons gives near-perfect prediction of the corresponding property of the other photon. In an imaging context, this second photon with known properties can then be used to probe an object. Using the correlations inherent in this entanglement we are able to increase the resolution of an imaging system and suppress both sensor noise and background light. Our immediate goal is to recover an image of the object without interference from any thermal background or other light sources that might otherwise obscure or confuse what we are seeing. This work in the optical regime has strong parallels with proposals around quantum radar and it is an interesting exercise to consider what one might inform with respect to the other.

The US National Quantum Initiative Act of 2018 established a multi-agency program that aims to advance quantum information science (QIS) and promote application and commercialization. Agencies including the National Science Foundation, Department of Energy, Air Force, and National Institute of Standards and Technology (NIST) are growing their investments. The Quantum Economic Development Consortium (QED-C) is an industry-driven consortium supported by NIST and more than 185 corporations, universities and other organizations to enable and grow the quantum industry and supply chain. This presentation will provide an overview of US NQI programs, especially those with a focus on innovation and economic benefit.

Innovations in information sciences coming to fruition in 2021 and beyond are poised to redefine government, industry, and education as we know it today. This talk will focus on technologies that are poised to provide profound advancements in the information sciences domain as well as the implications of these technologies on computer security. Special emphasis will be placed on blockchain inspired architectures and distributed ledgers as well as Artificial Intelligence and Machine Learning (AI/ML) based solutions. The inherent vulnerabilities of these rapidly advancing technologies are of growing concern as investment is made into applying these tools to gain a strategic advantage in speed of response, analysis, and maneuver for both private industry and government applications.

The Quantum Communications Hub is one of four Hubs comprising the research and development end of the UK National Quantum Technologies Programme. This programme is now in its second phase (2019-2024), following a successful first phase that ran 2014-2019. Our Hub provides the UK focus for the quantum communications sector. In this talk I'll provide a brief overview of the Hub's phase 1 developments, which mainly concentrated on progressing quantum key distribution (QKD) towards wider application. The grand vision of the phase 2 Hub is integrated secure quantum communications at all distance scales. For practicality and flexibility, this involves free-space communications at the shortest distance scales, fibre-based communications at the metrolpolitan and inter-city distance scales covered by current fibre networking, and free-space communications to support the very longest distances required for global reach. I'll outline the Hub activities on short-range consumer QKD, fibre networking and long distance satellite-to-ground QKD. I'll also cover our work on new protocols, hybrid secure communications, standards and components. http://www.quantumcommshub.net/

Quantum key distribution is a quantum communication protocol which seeks to address potential vulnerabilities in data transmission and storage. One of the main challenges in the field is achieving high rates of secret key in lossy and turbulent free-space channels. In this scenario, most experimental demonstrations have used the polarization of photons as their qubit carriers, due to the relative robustness of polarization in free-space propagation. Time-bin or phase-based protocols are considered less practical due to the wave-front distortion caused by atmospheric turbulence. However, demonstrations of novel free-space interferometer designs are enabling interferometers to measure multimodal signals with high visibility. That means it is now viable to consider the prospects of implementing time-bin or phase-based protocols, which have demonstrated high key rates and long transmission distances in optical fiber. In this work, we present the possibilities of implementing time-bin protocols in turbulent free-space channels, using the coherent one-way protocol as the example. We present an analysis of the secret key rate and quantum bit error rate of the system, providing the errors due to noise counts, and the extinction ratio of the pulses. Finally, we developed a model to quantify the expected losses for a turbulence free-space channel, specifically for a free-space satellite-to-ground station channel.

The analysis of link loss is one of the first and most important steps for the design of an optical communication system. This is particularly vital in quantum communications systems where the information is encoded at the single photon level, and the quantum optical signal cannot be amplified deterministically. In most cases, the desired quantum bit error rate and secure key rate can only be achieved by minimizing the link attenuation and the background noise level in the quantum communication system. In optical fiber implementations, the transmission distance is inherently limited by the loss per unit distance of the optical fiber, meaning fully global coverage is not readily achievable with the current optical fiber backbone networks. To overcome the terrestrial link limitations for quantum communications, long-distance free-space links, using low-Earth orbit satellites are being proposed and implemented. Due to the optical link length, the main contributors to link losses are geometric loss, atmospheric attenuation, and losses associated with pointing and tracking errors. The total link loss is dominated by the geometric loss, therefore, it is important to analyze its importance in relation to the quantum communications link. In this paper, the loss of a low-Earth orbit satellite-to-ground (downlink) quantum communication link is analyzed. The analysis includes losses associate with the channel (geometric and atmospheric) and the receiver system. This paper also compares the data of a known satellite quantum communications mission, highlighting trade-offs in investment for satellite platform and optical ground station. Based on the link loss analysis, decoy state BB84 and E91 protocols were chosen to demonstrate the link performance under an example scenario. The work contributes to the design of the optical ground station for a CubeSat mission.

The next-generation information security is facing quantum threats from the recent progress in quantum technologies. Quantum cryptography can provide true randomness and secure distribution of keys, but is prevented from wide applications due to challenges in real implementation. We propose and demonstrate a practical hybrid scheme with various quantum-safe technologies for encrypted communications between data centers. Quantum random number generators, quantum key distribution, post-quantum and classical cryptography algorithms are integrated in the hybrid quantum-safe scheme to enhance data transfer security in Alibaba platform. Compared with quantum cryptography and post quantum cryptography solutions, the proposed triple-level security cryptographic scheme provides a layered cryptographic solution for different applications, and is compatible with existing solutions. The demonstration shows a first step of quantum-safe secure data transfer solution in real data center environment, with the advantages of low cost, high stability, and easy operation.

The optical shot-noise limit of a laser beam represents the classical limit in precision and signal to noise ratio achievable in optical sensors and imaging systems. It is known that quantum states of light, such as squeezed light and quantum correlated twin beams can be used to enhance precision and signal to noise ratio to beyond this limit. This promises optical sensors with fundamentally superior performance to the state of the art. While quantum-enhanced signal to noise ratio has been demonstrated with macroscopic powers of squeezed probe beam, demonstrations of quantum enhanced precision have remained at extremely low powers of light (femto-Watts). Here we will give examples where increasing SNR with quantum light is not sufficient to increase precision and we will review proof of principle experiments that have demonstrated sub shot noise precision, including for absorption spectroscopy and imaging. We will also report our efforts to achieve this sub-shot-noise precision performance for transmission measurement with ~0.1mW of average probe power, equating to ~10W peak power in a pulsed experiment. Time permitting, we will discuss how integrated optics and integrated electronics enables 10s GHz bandwidth in the detection of squeezed light, for integrated quantum sensor technology.

Nonlinear optical microscopy techniques have emerged as a set of successful tools for biological imaging. Stimulated emission microscopy belongs to a small subset of pump-probe techniques which can image non-fluorescent samples without requiring fluorescent labelling. However, its sensitivity has been shown to be ultimately limited by the quantum fluctuations in the probe beam. We propose and experimentally implement sub-shot-noise limited stimulated emission microscopy by preparing the probe pulse in an intensity-squeezed state. This technique paves the way for imaging delicate biological samples that have no detectable fluorescence with sensitivity beyond standard quantum fluctuations.

Quantum technologies containing key GaN laser components will enable a new generation of precision sensors, optical atomic clocks and secure communication systems for many applications such as next generation navigation, gravity mapping and timing since the AlGaInN material system allows for laser diodes to be fabricated over a wide range of wavelengths from the u.v. to the visible. We report our latest results on a range of AlGaInN diode-lasers targeted to meet the linewidth, wavelength and power requirements suitable for optical clocks and cold-atom interferometry systems. This includes the [5s²S_1/2-5p²P_1/2] cooling transition in strontium⁺ ion optical clocks at 422 nm, the [5s₂¹S₀-5p¹P₁] cooling transition in neutral strontium clocks at 461 nm and the [5s²s_1/2 – 6p²P_3/2] transition in rubidium at 420 nm. Several approaches are taken to achieve the required linewidth, wavelength and power, including an extended cavity laser diode (ECLD) system and an on-chip grating, distributed feedback (DFB) GaN laser diode.

An important part of optical sensing is interferometry, where direct or homodyne detection at the output of an interferometer yields information about small phase shifts. Classical interferometry operates at the shot-noise limit (SNL), caused by the photon structure of light and reached when an interferometer is fed with coherent light. The use of nonclassical light at the input of an interferometer enables overcoming the SNL. In particular, squeezed light is known to be less noisy than coherent light. An interferometer fed with strongly squeezed light can, in principle, provide the phase sensitivity at the Heisenberg limit, the ultimate limit allowed by the laws of physics. However, this supersensitive operation is strongly degraded by loss – both inside the interferometer and outside it, at the stage of detection. While the former (internal loss) seems to be inevitable, the latter (detection loss) can be overcome, and we demonstrate it in our recent experiment. The clue is to amplify light at the interferometer output using a phase-sensitive optical parametric amplifier. This device does not introduce additional noise, but it amplifies the fragile quantum signal and thus makes it tolerant to loss at the detection stage. In a proof-of-principle experiment, we build a polarization Mach-Zehnder interferometer and feed it with coherent light in one port and a squeezed vacuum in another port. At one output port, we amplify light with an optical parametric amplifier and measure a phase sensitivity of 13 mrad for 1500 photons in the interferometer. This result, achieved with 50% detection efficiency, overcomes the SNL by 3 dB. Moreover, by using stronger amplification, we can overcome the SNL under detection efficiency as low as 13%. Our results outline a way to use squeezed light for real-life sensing, where the detection efficiency cannot be very high, especially in spectral ranges like middle-infrared or terahertz.

In the paper by Weedbrook et. al,1 a post-selected model of Lloyd's original formulation of quantum illumination (QI)2 was used to show that quantum discord explains the underlying advantage of QI over conventional illumination. The same model was used by Ray et. al3 to show that the normalized Hilbert-Schmidt inner product (HSIP) is a valid distinguishability measure when analyzing quantum illumination. This post-selected model assumes that the detector always detects a photon whether it be from the signal or noise from the environment; thus, the vacuum is excluded from this model. In this paper, we include the vacuum back into these analyses. In the case of,1 we show that the conclusion is unaffected by the inclusion of the vacuum. We then analyze the effects of including the vacuum when distinguishing between a noisy signal and noise. In this analysis, we found that the normalized HSIP is not monotonic with respect to the parameter that controls the brightness of the noise. Because of this, the normalized Hilbert-Schmidt inner product cannot be used as a distinguishability as was seen in the post-selected model. To reconcile this problem, we used the proposed alternative fidelity measure defined in,4 and found that it is monotonic in the vacuum added model for all the examples considered.

Long range horizontal path imaging through atmospheric turbulence is hampered by spatiotemporally randomly varying shifting and blurring of scene points in recorded imagery. Although existing software based mitigation strategies can produce sharp and stable imagery of static scenes, it remains highly challenging to mitigate turbulence in scenes with moving objects such that they remain visible as moving objects in the output. In our work we investigate if and how neuromorphic cameras can be used for this challenge. We explore how the high temporal resolution of the event stream can be used to distinguish between the apparent motion due to turbulence and the actual motion of physical objects in the scene. We use this to propose an algorithm to reconstruct output image sequences where the static background of the scene is mitigated for turbulence, while preserving the moving objects in the scene. The algorithm is demonstrated on indoor experimental recordings of moving objects imaged through artificially generated turbulence.

The novel Compressed Sensing (CS) imaging technique possesses fundamental differences and in special cases outstanding advantages compared to conventional imaging. The crucial requirement is the validity of the “sparsity” assumption. Fulfilling this requirement enables the reconstruction of a high-resolution image/signal from very few low-resolution measurements. An excellent example of sparse signals are solar blind UV imaging applications. The image of a hot exhaust plume in front of the dark background is spatially sparse. Hence, a solar blind threat detection system may be considered using a single-pixel-camera equipped with the Compressed Sensing approach. This simple and cheap setup with a spatial light modulator and a single-pixel-detector measures only the brightness of a modulated target scene. It is necessary to reconstruct the original image from the obtained compressed data. Many reconstruction algorithms have been proposed and implemented for various CS applications. However, the demands for a CS threat warning system are very specific. Therefore, we built up a library of common reconstruction algorithms and studied their performance in terms of different image quality assessment metrics. In our investigations we utilized exemplary test scenes as well as a real dataset.

A new approach for imaging that is solely based on the time of flight of photons coming from the entire imaged scene, combined with a novel machine learning algorithm for image reconstruction: a spiking convolutional neural network (SCNN) named Spike-SPI (Spiking - Single Pixel Imager). The approach uses a single point detector and the corresponding time-counting electronics, which provide the arrival time of photons in the form of spikes distributed over time. This data is transformed into a temporal histogram containing the number of photons per arrival time. A SCNN that converts the 1D temporal histograms into a 3D image (2D image with depth map) by exploiting the feature extraction capabilities of convolutional neural networks (CNNs), the high dimensional compressed latent space representations of a variational encoder-decoder network structure, and the asynchronous processing capabilities of a spiking neural network (SNN). The performance of the proposed SCNN is analysed to demonstrate the state-of-the-art feature extraction capabilities of CNNs and the low latency asynchronous processing of SNNs that offer both higher throughput and higher accuracy in image reconstruction from the ToF data, when compared to standard ANNs. The results of Spike-SPI show an increase in spatial accuracy of 15% over then ANN, using the Intersection of Union (IoU) for the objects in the scene. While also delivering a 100% increase over then ANN in object reconstruction signal to noise ratio (RSNR) from ~3dB to ~6dB. These results are also consistent across a range of IRF (Instrument Response Functions) values and photo counts, highlighting the robust nature of the new network structure. Moreover, the asynchronous processing nature of the spiking neurons allow for a faster throughput and less computational overhead, benefiting from the operational sparsity in the single point sensor.

Technologies for manufacturing CMOS SPAD arrays are advancing rapidly towards dense nanoscale technologies accompanied by backside illumination and 3D stacking. This talk will review recent milestones in integrated CMOS SPAD sensors in academia and industry. The growing ecosystem of in-house and foundry manufacturing technologies underpinning these devices will be described. New opportunities for innovation have been created by these platforms in particular the ability to integrate complex digital signal and image processing close to the detectors. To illustrate this potential we will describe two recently developed CMOS SPAD arrays implementing multiple reconfigurable imaging modalities and show how the modalities can be conveniently combined to improve performance and create new capabilities. The first device is a 3D-stacked 90nm/40nm 256x256 imaging array for flash LIDAR with high dynamic range intensity and 3D time of flight modalities at reconfigurable spatial, distance and time scales. The second device is a 128x128 40nm CMOS front-side illuminated array with column parallel image processing implementing dynamic-vision and 3D time of light modes. Both devices employ on chip coarse histogramming to reduce I/O rates which have held back SPAD array imagers from achieving dynamic range compatible with outdoor background light levels. The intelligent conjunction of these imaging modalities (facilitated by the innate digital processing of SPAD imagers) will be shown to enable power and data rate reduction whilst achieving high dynamic range and image resolution.

This paper presents the electron and hole avalanche multiplication and excess noise characteristics based on bulk AlAs_0.56Sb_0.44 p-i-n and n-i-p homojunction diodes lattice matched to InP, with nominal avalanche region thicknesses of 0.6 -1.5 μm. From these, the bulk electron and hole impact ionization coefficients (α and β respectively), have been determined over an electric field range of 220-1250 kV/cm for α and from 360-1250 kV/cm for β for the first time. Excess noise characteristics suggest an β/α ratio as low as 0.005 for an avalanche region of 1.5 μm in this material, close to the theoretical minimum and significantly lower than AlInAs, InP, or even silicon. This material can be easily integrated with InGaAs for networking and sensing applications, with modeling suggesting that a sensitivity of -32.1 dBm at a bit-error rate (BER) of 1×10^-12 at 10 Gb/s at 1550 nm can be realized. This sensitivity can be improved even further by optimizing the dark currents and by using a lower noise transimpedance amplifier.

The measurement of the time of arrival of single photons with picoseconds precision has been subject to a growing interest in recent years. In this field, conversion electronics with ultimate precision becomes of the utmost importance not only for demanding applications but even for most advanced sensors characterization. We present the first fully-integrated Time-to-Amplitude Converter providing a state-of-art precision better than 6ps Full Width at Half Maximum (2.4ps rms) on a 12.5ns Full Scale Range. The TAC structure has been proven effective to combine picosecond precision with high linearity, i.e. lower than 1% rms. The single channel can achieve a conversion rate of several MHz and thanks to a low power dissipation and area occupation, it is also suitable to be the building block of a multichannel structure.

The addition of germanium to Si-based single-photon avalanche diode (SPAD) detectors can significantly increase the spectral range of these devices into the into the strategically important short-wave infrared (SWIR) region. We present the performance characteristics of small area (26 μm and 50 µm diameter) planar geometry Ge-on-Si SPAD detectors. There are many advantages for operating such SPAD detection in the SWIR region, these include: reduced eye-safety laser threshold, longer measurable ranges, improved depth resolution in range finding applications; and improved capability for imaging through obscurants such as precipitation and smoke. The time-correlated single-photon counting (TCSPC) technique has been utilized for the measurement of record low dark count rates (DCRs) and high single-photon detection efficiency. Specifically, the 26 µm diameter devices maintained DCR values < 100 kHz up to a temperature of 125 K for excess biases up to 6.6 %. The 50 µm diameter device consistently demonstrated DCRs a factor of approximately 4 times greater than 26 µm diameter devices, under identical operating conditions of excess bias and temperature, illustrating a dark count rate in proportion to the device volume. Single-photon detection efficiencies were found to reach a maximum of ~ 29 %, measured at a wavelength of 1310 nm and a temperature of 125 K. Due the record low dark currents observed, noise equivalent power values (NEP) down to 7.7 × 10-17 WHz-1/2 are obtained, significantly reduced when compared to both previous mesa geometry and larger area planar geometry Ge-on-Si SPADs, indicating much improved optical sensitivity levels attainable with these planar geometry devices. In addition to this, high speed operation was demonstrated, quantified by jitter values down to 134 ± 10 ps at a temperature of 100 K. These results demonstrate the potential of these devices for highly sensitive and high-speed LIDAR imaging in the SWIR.

Detecting and identifying objects inside a forest edge on the other side of an open field is an important task in defence and security applications. This can be difficult to achieve with passive imaging sensors because of the partial obscuration by the foliage. High-resolution 3D imaging enables separation of hidden objects from branches and leaves and can provide data for detection, recognition, and identification of partly occluded targets. We use a photon counting lidar system with panoramic scanning to produce high quality 3D data for this task. The FOI system is built around the Princeton Lightwave Inc. (PLI) Falcon detector which is a 32×128 pixel array of InGaAs Geiger-mode avalanche photodiodes. The system operates at 1557 nm and has been designed for suitable resolution at standoff ranges of 1 to 2 km. In this paper, we investigate the detection capability when combining measurements from multiple measurement positions. A field trial has been performed where data from the same scene was collected from different sensor positions. The system was mounted on a car and moved between different positions along a road. The measurements were performed first without and then with vehicles in the target area. The distance to the forest edge varied between from approximately 1.0 to 1.5 km, and the difference of the angle of incidence was approximately 45 degrees from the outer positions along the road. To merge the data from the different positions we apply registration of the data sets using derived point clouds to transform all data into a common coordinate system. Data from the different sensor positions is analyzed by overlaying the derived point clouds from the different positions. We compare data from different viewpoints to data from only one viewpoint. The results show that the combined point clouds from multiples positions covers more of scene than from a single position. We also perform change detection using registered point clouds from the same measurement positions. In the change detection we found the changes we had introduced (vehicles and equipment).

In recent years, there has been increasing interest in the use of Light Detection and Ranging (LiDAR) systems for measuring targets through visually degraded environments where man-made and natural obscurants such as smoke, fog, and haze can hinder the acquisition of high-resolution images. Single-photon time-of-flight LiDAR systems which employ the time correlated single photon counting (TCSPC) technique have emerged as a candidate technology for imaging in challenging environments due to the high sensitivity, excellent surface-to-surface resolution, and picosecond temporal resolution afforded by this approach. The time-of-flight LIDAR technique measures the round-trip time of flight of back-scattered photons, which when combined with optical scanning or use of multiple detectors, can obtain a three-dimensional profile of a target. These systems offer high resolution depth profiling in challenging measurement scenarios, for example at kilometre ranges and in turbid underwater environments, whilst maintaining low average optical power levels. In this work we present a bistatic single photon LiDAR system, designed for free-space imaging in highly attenuating environments, comprised of a picosecond pulsed fibre laser source at an operating wavelength of 1.55 µm and a 32 × 32 pixel format InGaAs/InP single photon avalanche diode (SPAD) detector array. This system, in conjunction with a newly developed advanced image processing algorithm, was used to obtain depth images of stationary targets, and three-dimensional videos of moving objects in real time, through high levels of atmospheric obscurants. We present analysis of the depth profiling of targets measured in obscurants corresponding to 5 attenuation lengths between transceiver at stand-off distances up to 150 metres and in high levels of solar background. The algorithm used in this analysis was designed for real time processing of sparse single photon data obtained in the presence of atmospheric obscurants and is well suited to scenarios with particularly high and non-uniform background levels such as observed when active imaging through obscurants.

We investigate three-dimensional profiling of targets in highly scattering underwater environments, obtained using the time-correlated single-photon counting (TCSPC) technique. This approach was implemented in laboratory conditions by using an optical detection system based on a linear array of single-photon detectors and a dedicated TCSPC module. The depth imaging system comprised a single-photon detection module, a TCSPC acquisition system, and a laser diode source in a bi-static transceiver configuration. The laser operated at a wavelength of 670 nm with a pulse duration of 120 ps at a repetition rate of 40 MHz, equivalent to a period of 25 ns. The laser provided a collimated line focus which horizontally illuminated the area of interest. The photon detection module consisted of an array of 16 × 1 silicon single photon avalanche diode (Si-SPAD) detectors built in custom silicon fabrication technology, with each SPAD having a photon detection efficiency of up to 28% at a wavelength of 670 nm. The timing information was measured by a dedicated TCSPC acquisition module, which included four four-channel time to amplitude converter (TAC) arrays. The system acquired time-correlated images with a timing bin duration of 1.6 picoseconds, which was equivalent to 180 μm depth resolution in water. The targets were placed in a 110 liter capacity tank, at a distance of approximately 1.65 meters in several underwater scattering environments, and were moving at a speed of 10 mm/s. These laboratory based experiments demonstrate depth profiles performed in scattering conditions equivalent up to 7.4 attenuation lengths between the transceiver and target, using acquisition times per line of approximately 30 ms, and the pulsed laser had an average optical power of less than 14.6 mW.

Quantum Lidar is a future technology that can mean different things to different people. To some it means detection and identification of classical-type lidar signals reflected from an illuminated target at or near the single photon level. This is facilitated by advances in semiconductor detector technology that allow highly efficient photocounting. To others it is more stringent, requiring exploitation of covertness associated with being essentially undetectable by the target in a thermal background, whilst allowing the lidar operator to filter her own signal from this noise. Again there is nothing specifically quantum about this. Any source that mimics of the energy rate per bandwidth seen by the illuminated object in the direction of the source can appear covert. In order to exploit quantum optics one can use inherent correlations, whether entangled or otherwise between light beams. Simple correlated optical beams can do this in two ways, perhaps by storing one beam as a reference and later performing correlated detection with the return signal in a phase sensitive manner. This is the “gold standard” for quantum lidar, but will be difficult outside of laboratory situations. In microscopy such phase control might be possible, or perhaps in the radio or microwave region for a quantum radar. Less challenging is a scenario in which an immediate local measurement of one beam conditions the beam sent to the target, allowing the return signal to be sifted from noise more easily. Here we will consider such a simple system, providing a range equation for a basic quantum lidar if it is to be operated covertly or openly. Open operation allows increased quantum signal brightness but also provides a quantum advantage, unspoofability – the lidar operator can in principle recognise their own return signal. We will also provide an analysis of quantum lidar detection based on quantum hypothesis testing and use this to perform Monte Carlo simulation of both target detections and false positive avoidance in a noisy background. The theory will be applied to experimental data.

Non-Line-of-Sight (NLOS) imaging uses fast illumination and detection to reconstruct images of scenes from indirect illumination. Light reflected off a relay surface is thereby used to view the scene. One approach to compute these reconstructions from the captured data is to transform them into line of sight wave propagation problems creating a virtual wave front to model a virtual camera at the location of the relay surface. Our NLOS imaging system samples the virtual wavefront at the virtual aperture. As in a line of sight camera, scene reconstruction for the virtual camera is achieved by propagating the virtual wave back into the scene. In line of sight cameras, this operation is often performed by a lens. For the virtual camera, we implement it computationally. This approach allows us to transfer methods for scene reconstruction, scene inference, and imaging from existing line of sight imaging approaches to NLOS imaging. In particular, we make use of fast wave propagation algorithms to create high speed memory efficient NLOS imaging. This allows us to reconstruct complex scenes in sub-second times for variable hardware configurations. In particular, our reconstruction methods allow us to use SPAD arrays in conjunction with laser scanning to improve capture speed. There is a large diversity of line of sight imaging approaches with different properties that probe different aspects of the scene. In principle, the Phasor Field Virtual Wave formalism allows us to turn any of them into a NLOS virtual camera. I will cover several examples of this process that yield different NLOS reconstructions, including 2D NLOS imaging, transient NLOS videos, and Visualization of higher order light paths from 4th and 5th bounces in the hidden scene.

In the past decade, optical non-line-of-sight (NLOS) sensing has evolved from a fundamental idea and laboratory proof-of-principle experiment to a more and more mature computational sensing method to obtain information which cannot accessed with conventional optical means. For instance, reconstruction of NLOS scenes has been demonstrated with large round trip path length, outdoors and in real-time. To reach this state of art, various powerful reconstruction algorithms and transient rendering software has been developed. Detailed reconstructions of complex scenarios show the feasibility of this technology to be used in various sensing tasks ranging from military and security operations to civilian search and rescue missions and scientific (e.g. archaeology) and medical sensing tasks. Nevertheless, the sensing and reconstruction limitations are not completely understood. This paper starts to discuss the necessary information to interpret NLOS data sets and reconstructions.

Despite the highly promising advances in Machine Learning (ML) and Deep Learning (DL) in recent years, DL requires significant hardware acceleration to be effective, as it is rather computationally expensive. Moreover, miniaturisation of electronic devices requires small form-factor processing units, with reduced SWaP (Size,Weight and Power) profile. Therefore, a completely new processing paradigm is needed to address both issues. In this context, the concept of neuromorphic (NM) engineering provides an attractive alternative, seen as the analog/digital implementation of biologically brain inspired neural networks. NM systems propagate spikes as means of processing data, with the information being encoded in the timing and rate of spikes generated by each neuron of a so-called spiking neural network (SNN). Based on this, the key advantages of SNNs are: less computational power required, more efficient and faster processing, much lower power consumption. This paper reports on the current state of the art in the field of NM systems, and it describes three application scenarios of SNN-based processing for security and defence, namely target detection and tracking, semantic segmentation, and control.

We report on the stress induced birefringence of 10 mm BK7 cubes bonded to 15 mm x 15 mm x 5 mm aluminium coupons using ultrashort pulse laser welding, hydroxide catalysis bonding, and an optical adhesive using a standard approach used in industry. It was observed that ultrashort pulse laser welding results in a low level of stress induced birefringence within an 85% optical aperture of the 10 mm cube. These levels are suitable for use in photography and microscopy applications as defined by the relevant ISO standard for permissible stress induced birefringence limits in optics. Hydroxide catalysis bonding was shown to approach and possibly exceed this limit, however, it must be noted that the bonding area of the hydroxide catalysis samples greatly exceeds that of the welding and adhesive bonded samples by a factor of 20 and thus will likely experience grater mechanical stress from defects on the metal surface. The induced stress in the adhesively bonded samples was found to be well-confined, with the retardation falling below the maximum acceptable limits for microscopy type applications of 10 nm/cm retardation within 0.5 - 1 mm of the glass-metal interface for the majority of samples tested. The hydroxide catalysis and ultrashort pulse laser welded samples have a significant increase in retardation in the region directly above the bonded surface compared to the adhesively bonded samples. This retardation decays rapidly as a function of distance from the bonded interface. In the case of ultrashort pulse laser welded samples, optimisation of the welding parameters has been shown to control the level of retardation within the interface region, thus reducing the overall effect of the weld on the bulk optic.

Designer drugs, also commonly known as new psychoactive substances (NPS), are increasingly in their prevalence and a challenge to toxicologists and forensic chemists. Synthetic cannabinoids (SCs) are among the largest group of NPS that have emerged in the illicit drug market all over the world. SCs may consist of different chemicals prepared in laboratories and herbal mixtures that said to be incense and not-for-human-consumption. The main aim of this paper is to investigate the use of electrochemical based methods for screening some of the emerging types of SC. More specifically, the paper takes electrochemistry approach called voltammetry to perform the detection and analysis of SCs whereby the main subjects for screening include STS-135 and 5F-ADB-PINACA. The expected result is that those compounds that belong to the same class should indicate almost similar behaviour to help achieve its objective, the paper reviews a number of recent publications relating to forensic drug analysis and much attention to electrochemical sensor methods.

Radio frequency (RF) signals propagate through most materials that we are surrounded by while light is blocked by many of these materials. This feature makes wireless networks based on light (which are also referred to as LiFi networks) inherently more secure. However, it can also lead to sudden link failure if the legitimate data link is blocked because of user movements or changes in device orientation. In this paper, the secrecy capacity has been analysed with the consideration of imperfect channel state information, random device orientation and probability of link blockage for the case of a single eavesdropper. It has been found that the secrecy capacity almost doubles in a standing activity as opposed to a sitting activity and that the density of blocking objects degrades the secrecy capacity in single access point networks. It is evident that environmental factors and user behaviour have a significant impact on the secrecy performance and, thus, need to be considered for robust physical layer security (PLS) design in LiFi networks.

Nature is endless inspiration for the design of many extraordinary things that enables many new developments from bird-inspired airplanes to bio-robotics. However, biological structures are usually not designed to carry high mechanical loads in extreme conditions such as high strength fan blades in aero-engines. The insufficient mechanical strength limits the application of bio-inspired materials. On the contrary, metallic alloys are widely used for high performance applications involving extreme environmental conditions ranging from high temperatures in aero-engines to high pressure in deep ocean. However, the properties of metallic alloys are not sufficiently adaptive in response to the environmental changes as bio-materials. In this talk, I will demonstrate that it is possible to design architected materials that not only have high strength, but also have adapting ability thanks to the mimicry of crystal microstructure. The crystal-inspired approach enables the employment of the hardening mechanisms of alloys to design extremely lightweight materials with extraordinary strength and truly damage tolerance while offering unprecedented opportunities to tailor the mechanical properties of meta-materials [1]. The mimicry of crystal microstructure leads to a new class of meta-materials (meta-crystals) containing hierarchical and tunable structures across multiple scales from nm to mm and beyond. I will demonstrate that we can readily change crystal-inspired meso-structures (via computer-aided design) and the intrinsic microstructure of materials by using multi-materials and tailoring the process parameters. I will show new ways to store, communicate, sense and actuate certain functionalities in meta-materials. Various materials (including high strength alloys Ti6Al4V, Inconel 718) were used to fabricate new meta-crystals by additive manufacturing (such as laser powder bed fusion) to study the behaviour and realise the potential of adaptive meta-crystals. References [1] Pham M-S, Liu C, Todd I, Lertthanasarn J. Damage-tolerant architected materials inspired by crystal microstructure. Nature 2019;565:305.

Cephalopods (squids, octopuses, and cuttlefish) have captivated the imagination of both the general public and scientists alike for more than a century due to their visually stunning camouflage displays, sophisticated nervous systems, and complex behavioral patterns. Given their unique capabilities and characteristics, it is not surprising that these marine invertebrates have emerged as exciting models for novel optical materials and photonic systems. Within this context, our laboratory has developed various cephalopod-derived and cephalopod-inspired materials with unique functionalities in the infrared region of the electromagnetic spectrum. Our findings hold implications for next-generation adaptive camouflage devices and advanced thermal management technologies.

Bonding of metals to transparent materials (glasses, crystals, etc.) is commonly used for several applications in modern defence manufacturing including for hermetic sealing and precision optics mounting. Common methods include the use of organic adhesives or glass frit interlayers as well as diffusion, anodic and arc bonding. Such techniques are typically esoteric and operator skill dependent. They can introduce large heat input risking the device integrity or are subject to post-process creep and volatile components outgassing, which can lead to contamination of optical surfaces and subsequent device degradation. Adhesives in particular are not truly hermetic and so are largely unsuitable for electro-optics and miniature lasers fabrication. They are sensitive to environment, swelling in the presence of moisture, softening at high temperatures or becoming stiff and brittle at low temperatures. All of the above are highly undesirable. Apart from limiting the range of material combinations possible to join, such bonding often ends up as a lengthy, error prone manufacturing step. This explains why so many manufacturers would like to replace such bonding with a more deterministic process. Recently [1] direct microwelding of glass to metal (BK7 and fused silica to Al) has been demonstrated utilising ultrafast lasers which offer non-contact fabrication with high precision, high process speed and very small heat affected zones. In this paper we will showcase a purpose-built ultrafast laser prototype for laser microwelding of 10-20mm thick bulk optics (lenses, waveplates, prisms) to flat aluminium or stainless steel mounts with sufficient bond strength for use in advanced manufacturing for defence applications. Various demonstrated case studies in aerospace electro-optics assemblies and flexible electronics hermetic sealing for device encapsulation will be discussed in detail including bond strength shear test characterisation, thermal and vibration cycling. This laser microwelding tool is suitable for early adoption of this microwelding technology and for process development in several other optical material welding applications (e.g. glass to silicon; glass to ceramic, Nd:YAG to metal, etc.).

The application of solid carbide tri-flute drills is important for machining high- precision holes. The main advantages of a tri-flute drill are high productivity, very good self-centering and relatively small deviation from the base axis of the hole. The profile of the helical chip groove in the radial section and the shape of the thinning of the drill are the most important factors controlling the cutting precision and overall performance. In this work, various types of groove shape have been investigated and a new method for designing and rationalizing the cutting part shape of a tri-flute drill has been developed. The key result of this paper is a new method of the design of the cutting edge with minimized change in the radius of curvature, which allows to more evenly distribute the force load in the cutting zone and, hence, to decrease the probability of the drill failure. A comprehensive study of the geometric parameters of the drill cutting edges allowed determining the necessary curvature with a minimum number of node points and accounting for the initial position of the transitional section and chisel edge angle. New relationships between the curvature of cutting edge and the shape of the chip groove derived in this work provide a theoretical foundation for the further development of practical recommendations for designing the high-performance tri-flute drills.

The article describes the construction of a control system for mechatronic technological complexes, such as machine tools and robots. Like the human brain, the core of the system uses methods of parallelism of computational processes to increase productivity through the use of hardware computational and communication units in the processor architecture. In particular, a method has been developed to improve the performance of calculating the inverse kinematics problem for a five-axis machining centre with a globe rotary table. To improve the efficiency of electrical industrial equipment control and ensure safety, a modular system based on a ring interface and a real-time communication protocol was developed. The structure of the control system is synthesized by a memory-centric approach. Computing units in the processor architecture and external automation control modules are represented as memory areas. This ensures simplicity and speed of interaction with the core of the system.

Nanofibers are one-dimensional nanostructures exhibiting smart physicochemical properties which enable their use in different fields such as photonics, biotechnology, optoelectronics and energy harvesting. Light-emitting or other active polymer nanofibers, made of conjugated polymers or of blends embedding chromophores or other functional dopants, such as inorganic nanowires, have attracted an increasing interest for the realization of new photonic tools and devices to be integrated in chips for microfluidics, diagnostics, bioimaging and quantum communication. In general, a single fiber can work as either incoherent or coherent source, and waveguide medium. Here we review our recent results on nanofibers for photonics and show how the material choice and the environmental conditions enable the realization of novel device geometries for waveguiding and amplified spontaneous emission. Additive manufacturing methods provide further degree of freedom for the device design. The research received funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement no. 682157, “xPRINT”).

We present the optical properties (such as refractive index, extinction coefficient) of four layer structures, which differ only in the azo dyes layer. We used the family of azo compounds, where electron-donating and electron withdrawing groups (OCH₃, CH₃, Br) were introduced to the benzene ring. Then, these azo dyes were mixed with poly(3- octylthiophene) (P3OT). Afterwards, the layered structure (i.e. glass/ITO/PEDOT:PSS/azo dye+P3OT) was produced. We found that by changing the substituent in the azo compound we change the photo-physical properties of multilayer structure. Thus, we can prepare layered structures that can have potential applications in optoelectronics as photovoltaic cells or organic light-emitting diodes.

Recently, many kinds of biological materials attract attention not only for bio- and medical applications but also for electronic and/or photonic devices as new renewable resources. Biomaterials such as DNA are basically insulating and transparent in original forms not being adequate for such industrial application. The drawbacks of DNA was overcome by complexation with other organic molecules in various fashions thanks to its highly complex and organized structure. DNA, only soluble in water, can be coupled to cationic surfactants, transforming it into hydrophobic polymer complex which can be easily dissolved in organic solvents and processed into thin films accompanying other compounds. Previously, we fabricated the bilayer devices composed of PMMA layer containing an azobenzene derivative and a cyanine dye doped DNA complex layer, and demonstrated laser wavelength tuning. Recently, we prepared single layer films composed of DNA-CTMA, azo polymer having push-pull substituents where laser dye were doped later with an immersion method. By choosing adequate combination of laser and azo dyes in order to eliminate or reduce the reabsorption of amplified photons, we have confirmed amplified spontaneous emission from the system through spectral line narrowing and superlinear dependence of light emission on pump intensity. Lasing and its wavelength tuning for the film were succeeded with a relatively compact optics of 10 cm dimension which is manipulatable by one mechanical knob. For further improvement, development of optimized materials is very important issue. We have synthesized an azocarbazole molecule with a cationic alkyl chain being able to couple to anionic sites of DNA. The results on photoinduced birefringence of the material will be described at the conference.

SILVER NANOCOMPOSITES: SYNTHESIS, PROPERTIES AND APPLICATION Railean-Plugaru Viorica1*, Pomastowski Pawel 1, Buszewski Boguslaw1,2 1Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University in Torun, Wileńska 4, 87-100 Torun, Poland 2Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland *Corresponding author Dr. Viorica Railean E-mail address: viorica.railean@umk.pl The development of biological method seems to be as simple and viable alternative to chemical and physical one. Currently a lot of research including even our works refers to silver nanoparticles because of their many advantages i.e. besides of antibacterial effect against a broad range of microorganisms (bacteria, fungus, parasites), nanomaterials have spurred numerous applications in electronics, nanomedicine, biomaterials, energy, and food due to their unique properties (e.g high surface plasmon resonance). Furthermore, analyzing the nowadays increasing ecological problems, although new applications appear on the horizon, the future will be more focused on the idea of sustainable synthesis development of silver nanoparticles. Certainly, searching for new safe source for the silver composites synthesis, taking into consideration the present needs, without compromising the future generations, will be of the increased interest. One of this solution is using of LAB strain from milk and products resulting from the processing of milk (e.g whey). Therefore, the purpose of this study firstly it was to design safe source for the silver nanocomposites synthesis using bacterial strain isolated from the whey and on the another hand to carry out a detailed analysis of the physicochemical properties of the synthesized silver nanocomposites, allowing to collect the maximum amount of information on the bioparticles composites and influence of them and antibiotic systems to the antimicrobial and antioxidant effect. In this fact, a series of spectroscopy, microscopy methods and spectrometric techniques were applied. Obtained result give the potential for application of biologically synthetized AgNPs for nanostructure-assisted laser desorption/ionization (NALDI) due to the surface plasmon resonance (SPR) properties of synthetized AgNCs. Metallic and nanostructured nanoparticles are chare donor for themselves and molecules bonded on their surface. Moreover, the obtained silver nanocomposites have been found to present both a high antimicrobial effect against antimicrobial pathogens as well as a high antioxidant effect. Acknowledgments: This work was supported by the „Advanced biocomposites for tomorrow's economy BIOG-NET” project that is carried out within the TEAM-NET program of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund.

This paper presents an algorithm-based change detection method for small-scale objects related to nuclear activities using geographic information system (GIS) data. From the nuclear nonproliferation perspective, the structural changes within the significantly suspected area for nuclear activities have to be captured. Additionally, the more amount of satellite imagery increases, e.g., CubeSats, the more systematic approach is required for change detection. Hence, the GIS vector data prescribed for the designated section is introduced as a guide layer in the process of change detection. It is supposed to stay up to date with a final interpretation to reflect the structure status for the next execution. The process of the proposed method consists of four steps: (1) Prior to change detection, satellite imagery of target areas is preprocessed, including the Gram-Schmidt pan-sharpening and image-to-image registration with a second-order rational polynomial coefficient (RPC) and nearest neighbour (NN) interpolation. (2) The before-and-after images obtained from the first step are analysed with the multivariate alteration detection (MAD), which produces pixel-based changes. The MAD output is imported as a change source layer in the process of change detection. (3) multi-temporal image object (MTIO) method is adopted for segmentation with all layers (4-band each and GIS vector layers). (4) The segmented layer stacks up behind the MAD layer to determine whether the MAD layer occupies over the threshold area in each segment, supported by the skeleton-based object linearity index (SOLI) and spectral homogeneity (SH) to minimise the shadow and building-lean effects. The Python programming language customised the MAD analysis, and the ENVI and eCognition support the rest process. The performance of the proposed method is reviewed with pixel-based accuracy assessment (precision, recall, and F1-score), and object-based criterion is also discussed in support of interpretation.

The helical groove, which has a complex shape in the radial section, strongly affects the performance of solid ceramic mills. The accuracy of shaping is strongly affected by the size of the grinding wheel and the kinematic parameters of its movement and rotation relative to the workpiece. Although it is possible to obtain the aforementioned properties using the existing methods, there does not exist a general approach the determination the acceptable ranges of the diameter of the grinding wheel and radius of curvature of its profiling section. In this paper we have analyzed the main features of the design of the profiling sections of grinding wheels, have formed a set of initial parameters that most efficiently implement the trajectory of the shaping movement, which in turn constitutes a new general method of shaping for the helical surfaces of ceramic cutters, have analyzed the character of rolling of a set of profiling sections on a helical surface, have derived new analytical relationships determining impacts of the grinding wheel design and parameters controlling the trajectory of the grinding wheel movement on the shape of the cutter profile in the axial section, and have demonstrated advantages of the developed general approach in designing a new ceramic mill. The new method of shaping allows to unambiguously realize movements of the grinding wheel on various machine layouts and to exclude the displacement of the shaping point by replacing rotation with displacement. Further development of this method will make it possible to replace five- coordinate machines with four-coordinate ones when manufacturing milling cutters with a helical surface that can significantly reduce the production costs.

Solid ceramic mills with a toroidal cutting surface are playing an important, steadily growing role in manufacturing products made of heat-resistant materials. However, properties of these mills have a drawback such as the low strength and, hence, their design requires the absence of zones with high concentration of stresses to reduce the probability of the brittle fracture. In this paper, a new approach to the formation of the cutting edge of solid ceramic end mills has been developed. Unlike the existing approaches, which are based on the shape of the helical groove on the periphery, the new approach is based on the shape of the cutting edge on the toroidal cutting surface determining the shape of the helical surface of the cutter on the radial section. The new method allows finding ranges, in which constant angle cutting edges in the toroidal region exist, and developing multiple new designs of solid end mills with varying combinations of geometric parameters. One of the most important advantages of this method is the ability to determine the ranges, where a smooth cutting edge in all areas of the cutting part of the cutter exists. The derived analytical dependencies can be used to develop new designs of tools of a special shape with a rational combination of geometric parameters of cutting edges with accounting for the radii of the torus surface and the radius of the cutter.