Electrically Programmable Probabilistic Bit Anti-Correlator on a Nanomagnetic Platform
preprint
posted on 2020-01-18, 09:08 authored by Mason McCray, Md Ahsanul Abeed, Supriyo BandyopadhyaySupriyo BandyopadhyayProbabilistic computing algorithms require electrically programmable
stochasticity to encode arbitrary probability functions and controlled
stochastic interaction or correlation between probabilistic (p-) bits. The
latter is implemented with complex electronic components leaving a large
footprint on a chip and dissipating excessive amount of energy. Here, we show
an elegant implementation with just two dipole-coupled magneto-tunneling
junctions (MTJ), with magnetostrictive soft layers, fabricated on a
piezoelectric film. The resistance states of the two MTJs (high or low) encode
the p-bit values (1 or 0) in the two streams. The first MTJ is driven to a
resistance state with desired probability via a current or voltage that
generates spin transfer torque, while the second MTJ’s resistance state is
determined by dipole coupling with the first, thus correlating the second p-bit
stream with the first. The effect of dipole coupling can be varied by
generating local strain in the soft layer of the second MTJ with a local
voltage (~ 0.2 V) and that varies the degree of anti-correlation between the
resistance states of the two MTJs and hence between the two streams (from 0% to
100%). This paradigm generates the anti-correlation with “wireless” dipole
coupling that consumes no footprint on a chip and dissipates no energy, and it
controls the degree of anti-correlation with electrically generated strain that
consumes minimal footprint and is extremely frugal in its use of energy. It can
be extended to arbitrary number of bit streams. This realizes an “all-magnetic”
platform for probabilistic computing.
Funding
NSF ECCS-1609303; NSF CCF-1815033
History
Email Address of Submitting Author
sbandy@vcu.eduORCID of Submitting Author
0000-0001-6074-1212Submitting Author's Institution
Virginia Commonwealth UniversitySubmitting Author's Country
- United States of America