Proposal for nanoscale cascaded plasmonic majority gates for non-Boolean computation

Abstract

Surface-plasmon-polariton waves propagating at the interface between a metal and a dielectric, hold the key to future high-bandwidth, dense on-chip integrated logic circuits overcoming the diffraction limitation of photonics. While recent advances in plasmonic logic have witnessed the demonstration of basic and universal logic gates, these CMOS oriented digital logic gates cannot fully utilize the expressive power of this novel technology. Here, we aim at unraveling the true potential of plasmonics by exploiting an enhanced native functionality - the majority voter. Contrary to the state-of-the-art plasmonic logic devices, we use the phase of the wave instead of the intensity as the state or computational variable. We propose and demonstrate, via numerical simulations, a comprehensive scheme for building a nanoscale cascadable plasmonic majority logic gate along with a novel referencing scheme that can directly translate the information encoded in the amplitude and phase of the wave into electric field intensity at the output. Our MIM-based 3-input majority gate displays a highly improved overall area of only 0.636 μm2 for a single-stage compared with previous works on plasmonic logic. The proposed device demonstrates non-Boolean computational capability and can find direct utility in highly parallel real-time signal processing applications like pattern recognition.

Logic Synthesis for Established and Emerging Computing

“…With transistor dimensions reaching their scaling limits, it is interesting to look at disruptive computation paradigms offered by emerging nanotechnologies. Examples of majority-based beyond CMOS technologies include, but are not limited to, quantum-dot cellular automata (QCA, [6]), nanomagnet logic [83], spin-based devices (e.g., spin-wave devices [84] and spin torque majority gates [85]), and plasmonic-based devices [86]. Here, we describe as examples plasmonic-based devices and QCA, and we illustrate how logic synthesis data structures and algorithms described so far can be employed in order to realize logic circuits based on these new paradigms of computation.…”

“…1) Plasmonic-Based Devices: Plasmonic-based devices [86] described hereafter are based on the propagation of surface plasmon polaritons (SPP, [87]), which are electromagnetic waves propagating at the interface between a dielectric and a metal. In particular, plasmonic-based logic makes use of the phase φ of the SPP as logic variable.…”

“…Functionality: The phase of interfering SPP waves follows the majority rule; this makes the three-input majority function easy to realize with plasmonic-based devices [86]. Fig.…”

“…Thanks to the physics of plasmonic devices that can be abstracted as multivalued logic, it has been shown [86] that a nine-input majority gate can be easily realized using four three-input plasmonic devices. Note that the best realization of majority-9 in binary-valued logic known so far uses 15 majority-3 gates [55], and thus plasmonic devices may be more efficient (as compared to other wavebased devices) to realize logic circuits.…”

Modeling and Optimization of Plasmonic Detectors for Beyond-CMOS Plasmonic Majority Logic Gates

“…However, direct detection of the phase of a plasmonic signal with a frequency of hundreds of THz is very challenging if not impossible. An additional reference signal can be used to convert phase information to signal amplitude [17]. With this approach, various input combinations result in different output levels.…”