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Full-adder based on coherent quantum dynamics for energy efficient computing

Quantum technologies Reversible computing VLSI circuits HPC systems
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Design of a quantum based single-bit full-adder with greater energy efficiency than currently existing transistor-based technologies. The encoding of information in only a few electrons trapped inside a semiconductor system of three quantum dots allows the execution of a full-adder through coherent quantum dynamics, which are inherently energy conservative.

TRL: 2

Theoretical model based on a realistic, experimentally verified triple quantum dot system. Simulations show the full-adder can be operated with a wide range of realistic parameters, allowing flexibility in the implementation. Given that other triple quantum dot systems have been demonstrated in a lab environment for other purposes, a first proof-of-concept experiment for this technology to achieve TRL 3 is expected to be straightforward.

Background and description

Current semiconductor technology is reaching its limits, with further miniaturization incurring heavy thermal loads due to the dissipative nature of transistor-based devices, which will subsequently lead the performance to plateau. At the same time, over the past decades, the research and development of quantum computation has grown exponentially.
The proposed technology is a spin-off from this research, where the main purpose is, instead, to exploit a binary encoding of logic in low-energy quantum states to do classical computation with reduced energy cost. Related technologies (e.g. Quantum Dot Cellular Automata) have been proposed for energy efficient computation, however their experimental development has been hindered by the complexity of the devices, which require dozens of quantum dots for even the simplest operations. The present model uses a triple quantum dot system to execute the addition of two bits through a series of Fredkin gates, which swap the state of two bits conditional on a third bit. The sum of two bits is a fundamental operation in any computer’s Arithmetic and Logic Unit (ALU). The dynamics of the Fredkin gate are implemented through the quantum coherent dynamics of electrons tunneling between the quantum dots, which are inherently conservative.

Applications

  • High-Performance Computing (HPC) Systems
  • Very Large Scale Integration (VLSI) Circuits
  • Large-scale data centers
  • Reversible computing

Benefits

  • Significantly improved energy efficiency of future computing technologies, specially in the realm of HPC systems.
  • Compatibility with industrial standards in semiconductor fabrication: the usage of semiconductor quantum dots is a great advantage given their compatibility with the currently advanced industrial standards.

Inventors

  • Yasser Rashid Revez Omar
  • João Pedro Gomes Moutinho
  • Sougato Bose
  • Marco Pezzutto
  • António Tavares da Costa

Patents

  • Y. Omar, M. Pezzutto, S. Bose, A. T. Costa, J. M. Moutinho, Externally classical Fredkin and C-NOT gate based on reversible quantum dynamics comprising single-level quantum dots, respective full adder and operation method thereof, PCT/PT2021/050022, PCT, 24-07-2020,
    | Abstract
  • Y. Omar, A. T. Costa, S. Bose, M. Pezzutto, J. M. Moutinho, Porta lógica de Fredkin e C-NOT externamente clássica baseada em dinâmica quântica reversível composta por pontos quânticos de um nível, respectivo somador completo e método de operação do mesmo, PT116602, National, Granted, 24-07-2020, Portugal,
    | Abstract

    • REFERENCE: PI-1020

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