Sunil Pai

I'm a Quantum Architect at PsiQuantum Corp. in Palo Alto since 2022, where I contribute across the entire stack: I build classical and quantum simulation tools, run photonic experiments, invent calibration algorithms, and contribute to data analysis automation pipelines. At PsiQ, I specialize in quantum photonic single-photon switch multiplexers.

Previously: I am a Stanford lifer, getting my BS in Physics (Honors, 2015) and masters in CS (AI, 2016) at Stanford University before my PhD in photonic computing (EE, 2022). From 2021 to 2022, I was an AI resident at Google X, Moonshot Factory running large-scale constrained optimizations for photonic inverse design. Prior to my PhD, I was a data scientist and engineer at Stella AI, a now-acquired AI startup in the recruiting space where I developed Bayesian job-candidate recommendation models.

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Research

I'm interested in photonics, computing hardware, physics, deep learning, generative AI, and image processing. My PhD was, in short, "photonics for AI and AI for photonics." I built a novel analog optical matrix multiplication chip and integrated it with my custom optical probing station with a movable stage to enable the first ever neural net backpropaagation and cryptocurrency demonstrations on photonic circuits. These are included in my defense slides and the highlighted papers below.

Defense Slides

First-Author Papers

Experimentally realized in situ backpropagation for deep learning in photonic neural networks
Sunil Pai, Zhanghao Sun, Tyler W. Hughes, Taewon Park, Ben Bartlett, Ian A. D. Williamson, Momchil Minkov, Maziyar Milanizadeh, Nathnael Abebe, Francesco Morichetti, Andrea Melloni, Shanhui Fan, Olav Solgaard, David AB Miller
Science, 2023
paper / perspective / news / conference paper / arXiv / zenodo / patent / youtube feature

The first ever demonstration of optical backpropagation in photonic neural networks, paving the way for a new future for machine learning and ultra-fast photonic device error correction.

Experimental evaluation of digitally verifiable photonic computing for blockchain and cryptocurrency
Sunil Pai, Taewon Park, Marshall Ball, Michael Dubrovsky, Bogdan Penkovsky, Maziyar Milanizadeh, Nathnael Abebe, Francesco Morichetti, Andrea Melloni, Shanhui Fan, Olav Solgaard, David AB Miller
Optica, 2023
paper / conference paper / patent / arXiv / zenodo

The first ever demonstration of cryptocurrency and hash function evaluation in a photonic circuit implementing our patented hash function LightHash.

Matrix Optimization on Universal Unitary Photonic Devices
Sunil Pai, Ben Bartlett, Olav Solgaard, David AB Miller
Phys Rev Applied, 2019
paper / arXiv / visualizations / code

Exploring the matrix optimization of unitary networks for different sizes and architectures, relevant to both photonic circuits and machine learning applications.

Parallel Programming of an Arbitrary Feedforward Photonic Network
Sunil Pai, Ian A. D. Williamson, Tyler W. Hughes, Momchil Minkov, Shanhui Fan, Olav Solgaard, David AB Miller
JSTQE, 2020
paper / arXiv / patent

A new calibration algorithm for tuning arbitrary feedforward photonic networks is based on reciprocity in physics.

Power monitoring in a feedforward photonic network using two output detectors
Sunil Pai, Carson Valdez, Taewon Park, Maziyar Milanizadeh, Francesco Morichetti, Andrea Melloni, Shanhui Fan, Olav Solgaard, David AB Miller
Nanophotonics, 2023
paper

A new algorithm for measuring power in photonic feedforward networks noninvasively using phase tuners instead of taps or measured scattered light.

Scalable and self-correcting photonic computation using balanced photonic binary tree cascades
Sunil Pai, Shanhui Fan, Olav Solgaard, David AB Miller
arXiv, 2023
arXiv

A new mathematical framework for representing unitary and orthogonal matrices using binary tree cascades, useful for low-rank hardware implementations and representations.


Updated as of May 2024. Template credit: Jon Barron.