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1. Process Variation in Spoof Plasmon Interconnect: Consequences and Compensations

   https://doi.org/10.1109/RWS45077.2020.9050129  

   Bari, Md. Faizul; Roy Joy, Soumitra; Baten, Md. Zunaid; Mazumder, Pinaki (January 2020, 2020 IEEE Radio and Wireless Symposium (RWS))

   null (Ed.)

   The concept of chip-to-chip information propagation by spoof surface plasmon polariton (SSPP) metasurface at terahertz frequency has been introduced of late, that promises data transfer with high bandwidth, low crosstalk, and low energy consumption. As the exotic electromagnetic properties of the metasurface derive from its designed geometric pattern and periodicity, any possible variation of fabrication process parameters may affect the design pattern and consequently, the information capacity of SSPP interconnects. In this work, we have investigated the extent of performance degradation of SSPP interconnect with the statistical variation of the geometric pattern of the metasurface. We also described the technique of the design of an appropriate analog circuit so that the loss of signal integrity incurred by the process variation can be recuperated in real-time. 

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2. Optimized communication strategies with binary coherent states over phase noise channels

   https://doi.org/10.1038/s41534-019-0177-4  

   DiMario, M. T.; Kunz, L.; Banaszek, K.; Becerra, F. E. (July 2019, npj Quantum Information)

   Abstract The achievable rate of information transfer in optical communications is determined by the physical properties of the communication channel, such as the intrinsic channel noise. Bosonic phase noise channels, a class of non-Gaussian channels, have emerged as a relevant noise model in quantum information and optical communication. However, while the fundamental limits for communication over Gaussian channels have been extensively studied, the properties of communication over Bosonic phase noise channels are not well understood. Here we propose and demonstrate experimentally the concept of optimized communication strategies for communication over phase noise channels to enhance information transfer beyond what is possible with conventional methods of modulation and detection. Two key ingredients are generalized constellations of coherent states that interpolate between standard on-off keying and binary phase-shift keying formats, and non-Gaussian measurements based on photon number resolving detection of the coherently displaced signal. For a given power constraint and channel noise strength, these novel strategies rely on joint optimization of the input alphabet and the measurement to provide enhanced communication capability over a non-Gaussian channel characterized in terms of the error rate as well as mutual information. 

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3. Ultrafast control of vortex microlasers

   https://doi.org/10.1126/science.aba4597  

   Huang, Can; Zhang, Chen; Xiao, Shumin; Wang, Yuhan; Fan, Yubin; Liu, Yilin; Zhang, Nan; Qu, Geyang; Ji, Hongjun; Han, Jiecai; et al (February 2020, Science)

   The development of classical and quantum information–processing technology calls for on-chip integrated sources of structured light. Although integrated vortex microlasers have been previously demonstrated, they remain static and possess relatively high lasing thresholds, making them unsuitable for high-speed optical communication and computing. We introduce perovskite-based vortex microlasers and demonstrate their application to ultrafast all-optical switching at room temperature. By exploiting both mode symmetry and far-field properties, we reveal that the vortex beam lasing can be switched to linearly polarized beam lasing, or vice versa, with switching times of 1 to 1.5 picoseconds and energy consumption that is orders of magnitude lower than in previously demonstrated all-optical switching. Our results provide an approach that breaks the long-standing trade-off between low energy consumption and high-speed nanophotonics, introducing vortex microlasers that are switchable at terahertz frequencies. 

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4. Energy-Efficient Adiabatic Circuits Using Transistor-Level Monolithic 3D Integration

   Miketic, Ivan; Salman, Emre (September 2020, IEEE International System-on-Chip Conference (SOCC))

   Charge-recycling adiabatic circuits are recently receiving increased attention due to both high energy-efficiency and higher resistance against side-channel attacks. These characteristics make adiabatic circuits a promising technique for Internet-of-things based applications. One of the important limitations of adiabatic logic is the higher intra-cell interconnect capacitance due to differential outputs and cross-coupled pMOS transistors. Since energy consumption has quadratic dependence on capacitance in adiabatic circuits (unlike conventional static CMOS where dependence is linear), higher interconnect capacitance significantly degrades the overall power savings that can be achieved by adiabatic logic, particularly in nanoscale technologies. In this paper, monolithic 3D integrated adiabatic circuits are introduced where transistor-level monolithic 3D technology is used to implement adiabatic gates. A 45 nm two-tier Mono3D PDK is used to demonstrate the proposed approach. Monolithic inter-tier vias are leveraged to significantly reduce parasitic interconnect capacitance, achieving up to 47% reduction in power-delay product as compared to 2D adiabatic circuits in a 45 nm technology node. 

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5. Biphasic quasistatic brain communication for energy-efficient wireless neural implants

   https://doi.org/10.1038/s41928-023-01000-3  

   Chatterjee, Baibhab; Nath, Mayukh; Kumar_K, Gaurav; Xiao, Shulan; Jayant, Krishna; Sen, Shreyas (September 2023, Nature Electronics)

   Wearable devices typically use electromagnetic fields for wireless information exchange. For implanted devices, electromagnetic signals suffer from a high amount of absorption in tissue, and alternative modes of transmission (ultrasound, optical and magneto-electric) cause large transduction losses due to energy conversion. To mitigate this challenge, we report biphasic quasistatic brain communication for wireless neural implants. The approach is based on electro-quasistatic signalling that avoids transduction losses and leads to an end-to-end channel loss of only around 60 dB at a distance of 55 mm. It utilizes dipole-coupling-based signal transfer through the brain tissue via differential excitation in the transmitter (implant) and differential signal pickup at the receiver (external hub). It also employs a series capacitor before the signal electrode to block d.c. current flow through the tissue and maintain ion balance. Since the electrical signal transfer through the brain is electro-quasistatic up to the several tens of megahertz, it provides a scalable (up to 10 Mbps), low-loss and energy-efficient uplink from the implant to an external wearable. The transmit power consumption is only 0.52 μW at 1 Mbps (with 1% duty cycling)—within the range of possible energy harvesting in the downlink from a wearable hub to an implant. 

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