X0 probabilistic circuits
Programmable randomness
Extropic’s X0 chip proved four probabilistic circuits in silicon. They turn the thermal noise of ordinary transistors into samples from a probability distribution you program. Tune them below and watch them sample.
The samples on this page come from a pseudo-random generator running in your browser, not from an Extropic chip.
01 pbit
A weighted coin
Samples from a Bernoulli distribution: it outputs 0 or 1, and you set how likely the 1 is. The pbit is the building block of Extropic’s chips.
02 pdit
A weighted die
Samples from a categorical distribution: one of k outcomes, each with its own probability. This one has four outcomes, 0 to 3. Set their relative weights.
03 pmode
A programmable Gaussian
Samples a continuous value from a Gaussian (bell-curve) distribution. You program its mean, where the curve is centred, and its variance, how widely the values spread.
04 pmog
A mixture of Gaussians
Combines the two circuits above. For every sample, a pdit picks one of several pmodes, and that pmode produces the value. Here a pdit chooses between two.
Where they fit
From one circuit to a chip
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Circuits
pbit, pdit, pmode, pmog
Each pairs a sampled state with the distribution it comes from.
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X0 · 2025
Silicon prototype
Extropic’s first chip, which proved these circuits could be manufactured.
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XTR-0 · 2025
Desktop platform
Connects Extropic chips to a conventional processor, so early adopters can run programs on them.
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Z1 · taped out 2026
269,568 pbits
Each pbit wired to sixteen neighbours, so the chip samples a whole network of related variables in place.
To program them, Extropic publishes open-source libraries: THRML and Torx.