Guru Khalsa

Neuromorphic computing with nanoscale spintronic oscillators

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 108 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.

Theory of the SrTiO3 surface state two-dimensional electron gas

We present a theory of the quasi-two-dimensional electron gas (2DEG) systems that appear near the surface of SrTiO

Theory of t2g electron-gas Rashba interactions

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Conduction-band edge and Shubnikov-de Haas effect in low-electron-density SrTiO3

when a large external electric field attracts carriers to the surface. We find that nonlinear and nonlocal screening by the strongly polarizable SrTiO

Electronic structure of dopedd0perovskite semiconductors

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Weak localization, spin relaxation, and spin diffusion: Crossover between weak and strong Rashba coupling limits

lattice plays an essential role in determining 2DEG properties. The electronic structure always includes weakly bound bulklike bands that extend over many SrTiO

Spatially inhomogeneous electron state deep in the extreme quantum limit of strontium titanate

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Optical conductivity of thet2gtwo-dimensional electron gas

layers. At 2D carrier densities exceeding

Optical conductivity of the t2g two-dimensional electron gas

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