Experimental Demonstration of an On-Chip CMOS-Integrated 3T-1MTJ Probabilistic Bit -- A P-Bit
Pith reviewed 2026-05-10 18:41 UTC · model grok-4.3
The pith
A circuit of three transistors and one stochastic magnetic tunnel junction produces tunable random bits integrated on a CMOS chip.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The authors have fabricated and tested an on-chip 3T-1MTJ P-Bit that exhibits rail-to-rail stochastic output behavior, marking the first such demonstration with a stochastic MTJ in a complete CMOS integration.
What carries the argument
The 3T-1 sMTJ probabilistic bit circuit, where the stochastic magnetic tunnel junction acts as the source of tunable randomness controlled by the transistor network.
If this is right
- The P-Bit can serve as a building block for probabilistic logic circuits, as verified through simulations.
- Integration with CMOS allows for monolithic large-scale probabilistic computing architectures on chips.
- Such devices support low-power solutions for probability-encoded computational problems.
- Neuromorphic computing schemes can incorporate this P-Bit for enhanced capabilities.
Where Pith is reading between the lines
- If scaled, arrays of these P-Bits could solve optimization and sampling problems more efficiently than deterministic methods in certain domains.
- The successful integration suggests that similar stochastic devices could be combined with digital logic on the same die without process conflicts.
- Testing in actual probabilistic algorithms beyond simulations would be a next step to validate system-level benefits.
Load-bearing premise
The stochastic switching properties of the magnetic tunnel junction are preserved through the CMOS fabrication steps and electrical environment without significant degradation.
What would settle it
If repeated measurements of the P-Bit output show deterministic rather than stochastic voltage levels or no response to tuning voltages after integration, the central claim would be invalidated.
read the original abstract
Ongoing semiconductor scaling challenges and the rise of neuromorphic computing have sparked interest in exploring novel computing schemes to achieve higher power efficiency and computational capabilities. Probabilistic computing is one candidate that endows low power consumption, capability of solving probability-encoded computational problems, and the ease of integration with existing CMOS technology. A basic building block of this scheme is the probabilistic bit (P-Bit), which utilizes a novel device such as a stochastic magnetic tunnel junction (sMTJ) to generate tunable randomness by nature. This work presents the first experimental demonstration of a fully CMOS-integrated sMTJ-based P-Bit, capable of generating rail-to-rail stochastic output with a mere collection of 3 transistors + 1 sMTJ. Furthermore, simulations also confirm this P-Bit's functionality in probabilistic logic circuits. The demonstration of such P-Bit paves the way towards realizing monolithic large-scale probabilistic computing architecture on CMOS chips.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper claims the first experimental demonstration of a fully CMOS-integrated stochastic MTJ (sMTJ)-based probabilistic bit (P-Bit) realized with a 3T-1MTJ circuit that produces rail-to-rail stochastic output. Simulations are said to confirm functionality within probabilistic logic circuits, with the overall goal of enabling monolithic large-scale probabilistic computing on CMOS chips.
Significance. If the experimental results are substantiated, the work would be significant for probabilistic computing by showing that a minimal 3T-1MTJ topology can be monolithically integrated with standard CMOS while preserving tunable stochastic behavior, thereby supporting low-power, scalable hardware for probability-encoded algorithms.
major comments (1)
- [Abstract] The central claim is an experimental demonstration, yet the provided manuscript text contains no measured waveforms, output statistics, error bars, device parameters, or integration-process details to verify that rail-to-rail stochastic switching was achieved post-fabrication. This directly bears on the soundness of the primary result.
minor comments (1)
- [Abstract] The abstract uses the informal phrase 'a mere collection of'; a more precise formulation such as 'using only three transistors and one sMTJ' would be appropriate for a journal submission.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback. We address the major comment below and will strengthen the manuscript accordingly.
read point-by-point responses
-
Referee: [Abstract] The central claim is an experimental demonstration, yet the provided manuscript text contains no measured waveforms, output statistics, error bars, device parameters, or integration-process details to verify that rail-to-rail stochastic switching was achieved post-fabrication. This directly bears on the soundness of the primary result.
Authors: We agree that the manuscript text would benefit from more explicit descriptions of the experimental results. The full manuscript contains measured data from the fabricated 3T-1MTJ circuit, including waveforms demonstrating rail-to-rail stochastic output and supporting statistics. In the revised version we will add detailed textual descriptions of these measured waveforms, output statistics with error bars, extracted device parameters, and the CMOS integration process details to better substantiate the experimental claims. revision: yes
Circularity Check
No significant circularity in experimental demonstration
full rationale
The paper is an experimental demonstration of a 3T-1MTJ P-Bit after CMOS integration, with the central claim resting on fabrication, integration, and measurement of stochastic output rather than any derivation chain, first-principles prediction, or fitted model. No equations, ansatzes, or predictions are presented that could reduce to inputs by construction; the abstract and provided text reference simulations only in passing without load-bearing self-citations or uniqueness theorems. The result is therefore self-contained as an empirical finding with no circular steps.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Stochastic magnetic tunnel junctions generate tunable randomness suitable for P-bits
Lean theorems connected to this paper
-
IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
first experimental demonstration of a fully CMOS-integrated sMTJ-based P-Bit, capable of generating rail-to-rail stochastic output with a mere collection of 3 transistors + 1 sMTJ
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
Works this paper leans on
-
[1]
Inexact computing using probabilistic circuits: Ultra low-power digital processing,
J. Kim and S. Tiwari, “Inexact computing using probabilistic circuits: Ultra low-power digital processing, ” ACM J. Emerg. Technol. Comput. Syst., vol. 10, no. 2, pp. 1–23, Feb. 2014
work page 2014
-
[2]
Probabilistic deep spiking neural systems enabled by magnetic tunnel junction,
A. Sengupta, M. Parsa, B. Han, and K. Roy, “Probabilistic deep spiking neural systems enabled by magnetic tunnel junction, ” IEEE Trans. Electron Devices, vol. 63, no. 7, pp. 2963–2970, July 2016
work page 2016
-
[3]
Y . Bai, D. Fan, and M. Lin, “Stochastic-based synapse and soft-limiting neuron with spintronic devices for low power and robust artificial neural networks, ” IEEE Trans. Multi-scale Comput. Syst., vol. 4, no. 3, pp. 463–476, July 2018
work page 2018
-
[4]
Implementing Bayesian networks with embedded stochastic MRAM,
R. Faria, K. Y . Camsari, and S. Datta, “Implementing Bayesian networks with embedded stochastic MRAM, ” AIP Adv., vol. 8, no. 4, p. 45101, Apr. 2018
work page 2018
-
[5]
Survey of stochastic-based computation paradigms,
M. Alawad and M. Lin, “Survey of stochastic-based computation paradigms, ” IEEE Trans. Emerg. Top. Comput., vol. 7, no. 1, pp. 98–114, Jan. 2019
work page 2019
-
[6]
Weighted p -bits for FPGA implementation of probabilistic circuits,
A. Z. Pervaiz, B. M. Sutton, L. A. Ghantasala, and K. Y . Camsari, “Weighted p -bits for FPGA implementation of probabilistic circuits, ” IEEE Trans. Neural Netw. Learn. Syst., vol. 30, no. 6, pp. 1920– 1926, June 2019
work page 1920
-
[7]
Autonomous probabilistic coprocessing with petaflips per second,
B. Sutton, R. Faria, L. A. Ghantasala, R. Jaiswal, K. Y . Camsari, and S. Datta, “Autonomous probabilistic coprocessing with petaflips per second, ” IEEE Access, vol. 8, pp. 157238–157252, 2020
work page 2020
-
[8]
The promise of spintronics for unconventional computing,
G. Finocchio, M. Di Ventra, K. Y . Camsari, K. Everschor-Sitte, P . Khalili Amiri, and Z. Zeng, “The promise of spintronics for unconventional computing, ” J. Magn. Magn. Mater., vol. 521, no. 167506, p. 167506, Mar. 2021
work page 2021
-
[9]
Probabilistic computing with p-bits,
J. Kaiser and S. Datta, “Probabilistic computing with p-bits, ” Appl. Phys. Lett., vol. 119, no. 15, p. 150503, Oct. 2021
work page 2021
-
[10]
Massively parallel probabilistic computing with sparse Ising machines,
N. A. Aadit et al., “Massively parallel probabilistic computing with sparse Ising machines, ” Nat. Electron., vol. 5, no. 7, pp. 460–468, June 2022
work page 2022
-
[11]
Bayesian neural networks using magnetic tunnel junction-based probabilistic in- memory computing,
S. Liu et al., “Bayesian neural networks using magnetic tunnel junction-based probabilistic in- memory computing, ” Front. Nanotechnol., vol. 4, p. 1021943, Oct. 2022
work page 2022
-
[12]
Review of magnetic tunnel junctions for stochastic computing,
B. R. Zink, Y . Lv, and J.-P . Wang, “Review of magnetic tunnel junctions for stochastic computing, ” IEEE J. Explor. Solid-state Comput. Devices Circuits, vol. 8, no. 2, pp. 173–184, Dec. 2022
work page 2022
-
[13]
Unconventional computing based on magnetic tunnel junction,
B. Cai et al., “Unconventional computing based on magnetic tunnel junction, ” Appl. Phys. A Mater. Sci. Process., vol. 129, no. 4, p. 236, Apr. 2023
work page 2023
-
[14]
A full-stack view of probabilistic computing with p-bits: Devices, architectures, and algorithms,
S. Chowdhury et al., “A full-stack view of probabilistic computing with p-bits: Devices, architectures, and algorithms, ” IEEE J. Explor. Solid-state Comput. Devices Circuits, vol. 9, no. 1, pp. 1–11, June 2023
work page 2023
-
[15]
Probabilistic neural computing with stochastic devices,
S. Misra et al., “Probabilistic neural computing with stochastic devices, ” Adv. Mater., vol. 35, no. 37, p. e2204569, Sept. 2023
work page 2023
-
[16]
C. Duffee et al., “An integrated-circuit-based probabilistic computer that uses voltage-controlled magnetic tunnel junctions as its entropy source, ” Nat. Electron., pp. 1–10, Aug. 2025
work page 2025
-
[17]
J. Z. Sun, C. Safranski, S. Koswatta, P . Hashemi, and A. D. Kent, “Superparamagnetic and stochastic- write magnetic tunnel junctions for high-speed true random number generation in advanced computing, ” J. Phys. D Appl. Phys., vol. 59, no. 1, p. 13002, Jan. 2026
work page 2026
-
[18]
Low-barrier nanomagnets as p-bits for spin logic,
R. Faria, K. Y . Camsari, and S. Datta, “Low-barrier nanomagnets as p-bits for spin logic, ” IEEE Magn. Lett., vol. 8, pp. 1–5, 2017
work page 2017
-
[19]
Implementing p-bits With Embedded MTJ,
K. Y . Camsari, S. Salahuddin, and S. Datta, “Implementing p-bits With Embedded MTJ, ” IEEE Electron Device Lett., vol. 38, no. 12, pp. 1767–1770, Dec. 2017
work page 2017
-
[20]
p-Transistors, p-bits and p-circuits for an invertible logic,
K. Y . Camsari, “p-Transistors, p-bits and p-circuits for an invertible logic, ” in 2017 75th Annual Device Research Conference (DRC), IEEE, June 2017, pp. 1–2
work page 2017
-
[21]
P-bits for probabilistic spin logic,
K. Y . Camsari, B. M. Sutton, and S. Datta, “P-bits for probabilistic spin logic, ” Appl. Phys. Rev., vol. 6, no. 1, p. 11305, Mar. 2019
work page 2019
-
[22]
From Charge to Spin and Spin to Charge: Stochastic Magnets for Probabilistic Switching,
K. Y . Camsari et al., “From Charge to Spin and Spin to Charge: Stochastic Magnets for Probabilistic Switching, ” Proc. IEEE, vol. 108, no. 8, pp. 1322–1337, Aug. 2020
work page 2020
-
[23]
Training deep Boltzmann networks with sparse Ising machines,
S. Niazi, S. Chowdhury, N. A. Aadit, M. Mohseni, Y . Qin, and K. Y . Camsari, “Training deep Boltzmann networks with sparse Ising machines, ” Nat. Electron., vol. 7, no. 7, pp. 610–619, June 2024
work page 2024
-
[24]
B. R. Zink et al., “Tunable spintronic devices with different switching mechanisms for probabilistic and stochastic computing, ” Phys. Rev. Appl., vol. 24, no. 4, p. 47001, Oct. 2025
work page 2025
-
[25]
Configurable p-Neurons Using Modular p-Bits,
S. Bunaiyan et al., “Configurable p-Neurons Using Modular p-Bits, ” arXiv [cs.ET], Jan. 2026
work page 2026
-
[26]
Theory of tunnel magnetoresistance and spin filter effect in magnetic tunnel junctions,
H. Itoh, “Theory of tunnel magnetoresistance and spin filter effect in magnetic tunnel junctions, ” J. Phys. D Appl. Phys., vol. 40, no. 5, p. 1228, Feb. 2007
work page 2007
-
[27]
Tunneling magnetoresistance from a symmetry filtering effect,
W. H. Butler, “Tunneling magnetoresistance from a symmetry filtering effect, ” Sci. Technol. Adv. Mater., vol. 9, no. 1, p. 14106, Jan. 2008
work page 2008
-
[28]
D. C. Ralph and M. D. Stiles, “Spin transfer torques, ” J. Magn. Magn. Mater., vol. 320, no. 7, pp. 1190– 1216, Apr. 2008
work page 2008
-
[29]
Z. Diao et al., “Spin-transfer torque switching in magnetic tunnel junctions and spin-transfer torque random access memory, ” J. Phys. Condens. Matter, vol. 19, no. 16, p. 165209, Apr. 2007
work page 2007
-
[30]
Magnetoresistive random access memory,
D. Apalkov, B. Dieny, and J. M. Slaughter, “Magnetoresistive random access memory, ” Proc. IEEE Inst. Electr. Electron. Eng., vol. 104, no. 10, pp. 1796–1830, Oct. 2016
work page 2016
-
[31]
W. H. Choi et al., “A Magnetic Tunnel Junction based True Random Number Generator with conditional perturb and real-time output probability tracking, ” in 2014 IEEE International Electron Devices Meeting, IEEE, Dec. 2014, pp. 12.5.1–12.5.4
work page 2014
-
[32]
Future prospects of MRAM technologies,
S. Yuasa et al., “Future prospects of MRAM technologies, ” in 2013 IEEE International Electron Devices Meeting, IEEE, Dec. 2013, pp. 3.1.1–3.1.4
work page 2013
-
[33]
Spin dice: A scalable truly random number generator based on spintronics,
A. Fukushima et al., “Spin dice: A scalable truly random number generator based on spintronics, ” Appl. Phys. Express, vol. 7, no. 8, p. 83001, Aug. 2014
work page 2014
-
[34]
S. Liu et al., “Random bitstream generation using voltage-controlled magnetic anisotropy and spin orbit torque magnetic tunnel junctions, ” IEEE J. Explor. Solid-state Comput. Devices Circuits, vol. 8, no. 2, pp. 194–202, Dec. 2022
work page 2022
-
[35]
Measurement-driven neural-network training for integrated magnetic tunnel junction arrays,
W. A. Borders et al., “Measurement-driven neural-network training for integrated magnetic tunnel junction arrays, ” Phys. Rev. Appl., vol. 21, no. 5, p. 54028, May 2024
work page 2024
-
[36]
D. Vodenicarevic et al., “Low-Energy Truly Random Number Generation with Superparamagnetic Tunnel Junctions for Unconventional Computing, ” Phys. Rev. Appl., vol. 8, no. 5, p. 54045, Nov. 2017
work page 2017
-
[37]
Integer factorization using stochastic magnetic tunnel junctions,
W. A. Borders, A. Z. Pervaiz, S. Fukami, K. Y . Camsari, H. Ohno, and S. Datta, “Integer factorization using stochastic magnetic tunnel junctions, ” Nature, vol. 573, no. 7774, pp. 390–393, Sept. 2019
work page 2019
-
[38]
Probabilistic computing with binary stochastic neurons,
A. Z. Pervaiz, S. Datta, and K. Y . Camsari, “Probabilistic computing with binary stochastic neurons, ” in 2019 IEEE BiCMOS and Compound semiconductor Integrated Circuits and Technology Symposium (BCICTS), IEEE, Nov. 2019, pp. 1–6
work page 2019
-
[39]
Computing with invertible logic: Combinatorial optimization with probabilistic bits,
N. A. Aadit, A. Grimaldi, M. Carpentieri, L. Theogarajan, G. Finocchio, and K. Y . Camsari, “Computing with invertible logic: Combinatorial optimization with probabilistic bits, ” in 2021 IEEE International Electron Devices Meeting (IEDM), IEEE, Dec. 2021, pp. 40.3.1–40.3.4
work page 2021
-
[40]
K. Kobayashi et al., “CMOS plus stochastic nanomagnets enabling heterogeneous computers for probabilistic inference and learning, ” Nat. Commun., vol. 15, no. 1, p. 2685, Apr. 2023
work page 2023
-
[41]
Demonstration of nanosecond operation in stochastic magnetic tunnel junctions,
C. Safranski, J. Kaiser, P . Trouilloud, P . Hashemi, G. Hu, and J. Z. Sun, “Demonstration of nanosecond operation in stochastic magnetic tunnel junctions, ” Nano Lett., vol. 21, no. 5, pp. 2040–2045, Mar. 2021
work page 2040
-
[42]
L. Schnitzspan, M. Kläui, and G. Jakob, “Nanosecond true-random-number generation with superparamagnetic tunnel junctions: Identification of joule heating and spin-transfer-torque effects, ” Phys. Rev. Appl., vol. 20, no. 2, p. 24002, Aug. 2023
work page 2023
-
[43]
L. Soumah et al., “Entropy-assisted nanosecond stochastic operation in perpendicular superparamagnetic tunnel junctions, ” Phys. Rev. Appl., vol. 24, no. 1, p. L11002, July 2025
work page 2025
-
[44]
Stochastic 𝑝-Bits for Invertible Logic
K. Y . Camsari, R. Faria, B. M. Sutton, and S. Datta, “Stochastic 𝑝-Bits for Invertible Logic” , Phys. Rev. X, vol. 7, no. 3, p. 31014, July 2017
work page 2017
-
[45]
J. Daniel et al., “Experimental demonstration of an on-chip p-bit core based on stochastic magnetic tunnel junctions and 2D MoS2 transistors, ” Nat. Commun., vol. 15, no. 1, p. 4098, May 2024
work page 2024
-
[46]
A. Shukla et al., “A true random number generator for probabilistic computing using stochastic magnetic actuated random transducer devices, ” in 2023 24th International Symposium on Quality Electronic Design (ISQED), IEEE, Apr. 2023, pp. 1–10
work page 2023
-
[47]
J. Daniel et al., “Experimental demonstration of a compact spintronics-based platform with high- quality tunable random number generation for probabilistic computing, ” in Spintronics XVII, H. Jaffrès, J.- E. Wegrowe, M. Razeghi, and J. S. Friedman, Eds., SPIE, Oct. 2024, p. 93
work page 2024
-
[48]
Current control of time-averaged magnetization in superparamagnetic tunnel junctions,
M. Bapna and S. A. Majetich, “Current control of time-averaged magnetization in superparamagnetic tunnel junctions, ” Appl. Phys. Lett., vol. 111, no. 24, p. 243107, Dec. 2017
work page 2017
-
[49]
Design of stochastic nanomagnets for probabilistic spin logic,
P . Debashis, R. Faria, K. Y . Camsari, and Z. Chen, “Design of stochastic nanomagnets for probabilistic spin logic, ” IEEE Magn. Lett., vol. 9, pp. 1–5, 2018
work page 2018
-
[50]
Nanosecond random telegraph noise in in-plane magnetic tunnel junctions,
K. Hayakawa et al., “Nanosecond random telegraph noise in in-plane magnetic tunnel junctions, ” Phys. Rev. Lett., vol. 126, no. 11, p. 117202, Mar. 2021
work page 2021
-
[51]
J. Daniel, X. Zhang, Z. Chen, and J. Appenzeller, “Developing spin-transfer torque (STT)-resistant stochastic MTJs for complementary metal-oxide-semiconductor (CMOS)-integrated probabilistic bits, ” in Spintronics XVIII, H. Jaffrès, J.-E. Wegrowe, M. Razeghi, and J. S. Friedman, Eds., SPIE, Sept. 2025, p. 59
work page 2025
-
[52]
Experimental evaluation of simulated quantum annealing with MTJ-augmented p- bits,
A. Grimaldi et al., “Experimental evaluation of simulated quantum annealing with MTJ-augmented p- bits, ” in 2022 International Electron Devices Meeting (IEDM), IEEE, Dec. 2022.[53]N. S. Singh et al., “Hardware demonstration of feedforward stochastic neural networks with fast MTJ-based p-bits, ” pp. 1– 4, Dec. 2023
work page 2022
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