Parallel convolutional processing using an integrated photonic tensor core.

With the proliferation of ultrahigh-speed mobile networks and internet-connected devices, along with the rise of artificial intelligence (AI)1, the world is generating exponentially increasing amounts of data that need to be processed in a fast and efficient way. Highly parallelized, fast and scalable hardware is therefore becoming progressively more important2. Here we demonstrate a computationally specific integrated photonic hardware accelerator (tensor core) that is capable of operating at speeds of trillions of multiply-accumulate operations per second (1012 MAC operations per second or tera-MACs per second). The tensor core can be considered as the optical analogue of an application-specific integrated circuit (ASIC). It achieves parallelized photonic in-memory computing using phase-change-material memory arrays and photonic chip-based optical frequency combs (soliton microcombs3). The computation is reduced to measuring the optical transmission of reconfigurable and non-resonant passive components and can operate at a bandwidth exceeding 14 gigahertz, limited only by the speed of the modulators and photodetectors. Given recent advances in hybrid integration of soliton microcombs at microwave line rates3-5, ultralow-loss silicon nitride waveguides6,7, and high-speed on-chip detectors and modulators, our approach provides a path towards full complementary metal-oxide-semiconductor (CMOS) wafer-scale integration of the photonic tensor core. Although we focus on convolutional processing, more generally our results indicate the potential of integrated photonics for parallel, fast, and efficient computational hardware in data-heavy AI applications such as autonomous driving, live video processing, and next-generation cloud computing services.

Memristive effects in oxygenated amorphous carbon nanodevices.

Computing with resistive-switching (memristive) memory devices has shown much recent progress and offers an attractive route to circumvent the von-Neumann bottleneck, i.e. the separation of processing and memory, which limits the performance of conventional computer architectures. Due to their good scalability and nanosecond switching speeds, carbon-based resistive-switching memory devices could play an important role in this respect. However, devices based on elemental carbon, such as tetrahedral amorphous carbon or ta-C, typically suffer from a low cycling endurance. A material that has proven to be capable of combining the advantages of elemental carbon-based memories with simple fabrication methods and good endurance performance for binary memory applications is oxygenated amorphous carbon, or a-CO x . Here, we examine the memristive capabilities of nanoscale a-CO x devices, in particular their ability to provide the multilevel and accumulation properties that underpin computing type applications. We show the successful operation of nanoscale a-CO x memory cells for both the storage of multilevel states (here 3-level) and for the provision of an arithmetic accumulator. We implement a base-16, or hexadecimal, accumulator and show how such a device can carry out hexadecimal arithmetic and simultaneously store the computed result in the self-same a-CO x cell, all using fast (sub-10 ns) and low-energy (sub-pJ) input pulses.

Effects of CD40 binding on ovarian carcinoma cell growth and cytokine production in vitro.

The poor prognosis associated with ovarian carcinoma (OVCA) is linked to the high incidence of local recurrence. There is a pressing need to identify factors that can play a role in OVCA growth and spread. Here, we focused on CD40, a member of the tumour necrosis factor (TNF) receptor superfamily with important functions in immune response. The expression of CD40 has been reported on various types of carcinoma cells, but its biological role is still poorly understood. The aim of the present study was to investigate the expression and function of the CD40 in OVCA cell lines. Detectable CD40 levels ranging from low to very high were found on the cell surface of several OVCA cell lines by flow cytometry analysis. Co-culture with a murine cell line transfected with CD40 ligand (CD40L) inhibited cell growth and up-regulated the secretion of proinflammatory cytokines interleukin (IL)-6, IL-8 and TNF-alpha in high-level CD40-expressing OVCA cell lines. Similarly, an increase of IL-6 and IL-8 release could be obtained by adding a soluble form of CD40L to the OVCA cultures. These results suggest that CD40-CD40L interaction is an important pathway affecting growth regulation and cytokine production in OVCA.