Julian Büchel

dblp:232/1864 · DBLP profile ↗
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7ranked-venue papers
3as first author
7since 2021 · last 2025
0000-0001-9495-7150ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Systems, architecture and hardware · 4 · 1 first-author · 4 since 2021Artificial intelligence and machine learning · 2 · 2 first-author · 2 since 2021Software engineering, systems software and programming languages · 1 · 1 since 2021
YearPublicationVenuePosition
2025 Live Demonstration: Automated DNN Deployment on the IBM HERMES Project Chip
abstract
For this demonstration, we will showcase the operation of a software stack capable of automatically deploying Matrix-Vector Matrix (MVM) operations of diverse deep learning workloads in a pipelined-manner on a phase-change memory-based analog in-memory computing chip with high-accuracy. For a real chip, each deployment step will be highlighted for a transformer-based network trained to perform an organic chemical reaction prediction task. Additionally, using an emulated mode of operation, these steps will also be highlighted for a Resnet-based network, which has been trained to perform image classification, and a hybrid CNN/LSTM network trained to infer nucleotide sequences from sequences of amplitude values measured from a sequencing device.
Corey Lammie, Julian Büchel, Athanasios Vasilopoulos, Giacomo Camposampiero, Lionel Noussi, William Andrew Simon, Manuel Le Gallo, Abu Sebastian
ISCAS2
2025 A framework for analog-digital mixed-precision neural network training and inference
abstract
Recent advancements in AI hardware highlight the potential of mixed-signal accelerators, which integrate analog computation for matrix multiplications with reduced-precision digital operations, to achieve superior performance and energy efficiency. In this paper, we present a framework designed to perform hardware-aware training and inference evaluation of neural networks (NNs) on such accelerators. This framework extends an existing toolkit, the IBM Analog Hardware Acceleration Kit (AIHWKit), using a quantization library, enabling flexible layer-wise deployment in either analog or digital units, the latter with configurable precision and quantization options. Our combined framework supports simultaneous quantization-and analog-aware training as well as post-training calibration routines. It can also evaluate the accuracy of NNs when deployed on mixed-signal accelerators. We demonstrate the need of such a framework through ablation studies on a ResNet-based vision model and a BERT-based language model, highlighting the importance of its functionality for maximizing accuracy during deployment. Our contribution is open-sourced as part of the core code of AIHWKit [1].
Athanasios Vasilopoulos, Emma Boulharts, Corey Lammie, Julian Büchel, Hadjer Benmeziane, Manuel Le Gallo, Abu Sebastian
ISCAS4
2025 Analog Foundation Models
abstract
Analog in-memory computing (AIMC) is a promising compute paradigm to improve speed and power efficiency of neural network inference beyond the limits of conventional von Neumann-based architectures. However, AIMC introduces fundamental challenges such as noisy computations and strict constraints on input and output quantization. Because of these constraints and imprecisions, off-the-shelf LLMs are not able to achieve 4-bit-level performance when deployed on AIMC-based hardware. While researchers previously investigated recovering this accuracy gap on small, mostly vision-based models, a generic method applicable to LLMs pre-trained on trillions of tokens does not yet exist. In this work, we introduce a general and scalable method to robustly adapt LLMs for execution on noisy, low-precision analog hardware. Our approach enables state-of-the-art models — including Phi-3-mini-4k-instruct and Llama-3.2-1B-Instruct — to retain performance comparable to 4-bit weight, 8-bit activation baselines, despite the presence of analog noise and quantization constraints. Additionally, we show that as a byproduct of our training methodology, analog foundation models can be quantized for inference on low-precision digital hardware. Finally, we show that our models also benefit from test-time compute scaling, showing better scaling behavior than models trained with 4-bit weight and 8-bit static input quantization. Our work bridges the gap between high-capacity LLMs and efficient analog hardware, offering a path toward energy-efficient foundation models. Code is available at [github.com/IBM/analog-foundation-models](https://github.com/IBM/analog-foundation-models).
Julian Büchel, Iason Chalas, Giovanni Acampa, An Chen 0002, Omobayode Fagbohungbe, Hsinyu Tsai, Kaoutar El Maghraoui, Manuel Le Gallo, Abbas Rahimi, Abu Sebastian
NeurIPS1
2024 Analog AI as a Service: A Cloud Platform for In-Memory Computing
abstract
This paper introduces the Analog AI Cloud Composer platform, a service that allows users to access Analog In-Memory Computing (AIMC) simulation and computing resources over the cloud. We introduce the concept of an Analog AI as a Service (AAaaS). AIMC offers a novel approach for decreasing both the latency and energy usage associated with Deep Neural Network (DNN) inference and training. This platform democratizes access to AIMC computing, making it available to a broader audience, including researchers, developers, and businesses. Emphasizing a user-friendly, no-code approach, AAaaS integrates the Analog Hardware Acceleration Kit (AIHWKit) simulation platform within a fully managed cloud environment. We discuss the architecture of the Analog AI Cloud Composer (AAICC), focusing on its key services such as inference, training, and AIMC hardware access. The platform's design, grounded in cloud services and guidelines, ensures a secure, data-centric user experience with robust control and validation mechanisms.
Kaoutar El Maghraoui, Kim Tran, Kurtis Ruby, Borja Godoy, Jordan Murray, Manuel Le Gallo-Bourdeau, Todd Deshane, Pablo Gonzalez, Diego Moreda, Hadjer Benmeziane, Corey Lammie, Julian Büchel, Malte J. Rasch, Abu Sebastian, Vijay Narayanan
SSE12
2024 Improving the Accuracy of Analog-Based In-Memory Computing Accelerators Post-Training
abstract
Analog-Based In-Memory Computing (AIMC) inference accelerators can be used to efficiently execute Deep Neural Network (DNN) inference workloads. However, to mitigate accuracy losses, due to circuit and device non-idealities, Hardware-Aware (HWA) training methodologies must be employed. These typically require significant information about the underlying hardware. In this paper, we propose two Post-Training (PT) optimization methods to improve accuracy after training is performed. For each crossbar, the first optimizes the conductance range of each column, and the second optimizes the input, i.e, Digital-to-Analog Converter (DAC), range. It is demonstrated that, when these methods are employed, the complexity during training, and the amount of information about the underlying hardware can be reduced, with no notable change in accuracy (≤0.1%) when finetuning the pretrained RoBERTa transformer model for all General Language Understanding Evaluation (GLUE) benchmark tasks. Additionally, it is demonstrated that further optimizing learned parameters PT improves accuracy.
Corey Lammie, Athanasios Vasilopoulos, Julian Büchel, Giacomo Camposampiero, Manuel Le Gallo, Malte J. Rasch, Abu Sebastian
ISCAS3
2022 Network Insensitivity to Parameter Noise via Parameter Attack During Training
Julian Büchel, Fynn Faber, Dylan R. Muir
ICLR1
2021 Implementing Efficient Balanced Networks with Mixed-Signal Spike-Based Learning Circuits
abstract
Efficient Balanced Networks (EBNs) are networks of spiking neurons in which excitatory and inhibitory synaptic currents are balanced on a short timescale, leading to desirable coding properties such as high encoding precision, low firing rates, and distributed information representation. It is for these benefits that it would be desirable to implement such networks in low-power neuromorphic processors. However, the degree of device mismatch in analog mixed-signal neuromorphic circuits renders the use of pre-trained EBNs challenging, if not impossible. To overcome this issue, we developed a novel local learning rule suitable for on-chip implementation that drives a randomly connected network of spiking neurons into a tightly balanced regime. Here we present the integrated circuits that implement this rule and demonstrate their expected behaviour in low-level circuit simulations. Our proposed method paves the way towards a system-level implementation of tightly balanced networks on analog mixed-signal neuromorphic hardware. Thanks to their coding properties and sparse activity, neuromorphic electronic EBNs will be ideally suited for extreme-edge computing applications that require low-latency, ultra-low power consumption and which cannot rely on cloud computing for data processing.
Julian Büchel, Jonathan Kakon, Michel Perez, Giacomo Indiveri
ISCAS1