Torrejon Jacob, Riou Mathieu, Araujo Flavio Abreu, Tsunegi Sumito, Khalsa Guru, Querlioz Damien, Bortolotti Paolo, Cros Vincent, Yakushiji Kay, Fukushima Akio, Kubota Hitoshi, Yuasa Shinji, Stiles Mark D, Grollier Julie
Unité Mixte de Physique, CNRS, Thales, Université Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan.
Nature. 2017 Jul 26;547(7664):428-431. doi: 10.1038/nature23011.
Neurons in the brain behave as nonlinear oscillators, which develop rhythmic activity and interact to process information. Taking inspiration from this behaviour to realize high-density, low-power neuromorphic computing will require very large numbers of nanoscale nonlinear oscillators. A simple estimation indicates that to fit 10 oscillators organized in a two-dimensional array inside a chip the size of a thumb, the lateral dimension of each oscillator must be smaller than one micrometre. However, nanoscale devices tend to be noisy and to lack the stability that is required to process data in a reliable way. For this reason, despite multiple theoretical proposals and several candidates, including memristive and superconducting oscillators, a proof of concept of neuromorphic computing using nanoscale oscillators has yet to be demonstrated. Here we show experimentally that a nanoscale spintronic oscillator (a magnetic tunnel junction) can be used to achieve spoken-digit recognition with an accuracy similar to that of state-of-the-art neural networks. We also determine the regime of magnetization dynamics that leads to the greatest performance. These results, combined with the ability of the spintronic oscillators to interact with each other, and their long lifetime and low energy consumption, open up a path to fast, parallel, on-chip computation based on networks of oscillators.
大脑中的神经元表现为非线性振荡器,它们产生节律性活动并相互作用以处理信息。从这种行为中获取灵感来实现高密度、低功耗的神经形态计算将需要大量的纳米级非线性振荡器。一个简单的估计表明,要在拇指大小的芯片内装入以二维阵列形式排列的10个振荡器,每个振荡器的横向尺寸必须小于一微米。然而,纳米级器件往往噪声较大,且缺乏以可靠方式处理数据所需的稳定性。因此,尽管有多种理论方案和几个候选方案,包括忆阻振荡器和超导振荡器,但使用纳米级振荡器进行神经形态计算的概念验证尚未得到证实。在此,我们通过实验表明,纳米级自旋电子振荡器(磁隧道结)可用于实现与最先进神经网络精度相似的语音数字识别。我们还确定了导致最佳性能的磁化动力学机制。这些结果,再加上自旋电子振荡器相互作用的能力、它们的长寿命和低能耗,为基于振荡器网络的快速、并行片上计算开辟了一条道路。