The late physicist R.P. Feynman introduced a probabilistic computer capable of working with probabilities in
Magnetic tunnel junctions (MTJ) area key component of nonvolatile memory, or MRAM, a mass storage technology that uses magnetization to store information. There, thermal fluctuations usually pose a threat to the stable storage of information.
P-bits, on the other hand, work with thesethermal fluctuations in thermally unstable (stochastic) magnetic tunnel junctions. Previous collaborative research between Tohoku University and Purdue University has demonstrated a spintronics-based probabilistic computer at room temperature, consisting of stochastic magnetic tunnel junctions with millisecond relaxation times.
To make probabilistic computersa viable technology, it is necessary to develop stochastic magnetic tunnel junctions with much shorter relaxation times that reduce the timescale of p-bit fluctuations. This will effectively improve the speed and accuracy of the calculations.
Researchers have created a nanoscale devicemagnetic tunnel junctions with a flat magnetic axis. The direction of magnetization is updated every 8 nanoseconds on average - 100 times faster than the previous world record.
The group explained the mechanism behind this extremelya short relaxation time using entropy, a physical quantity used to represent the stochasticity of systems that were not previously considered for the dynamics of magnetization. Deriving a universal equation governing the entropy in the dynamics of magnetization, they found that the entropy increases rapidly in magnetic tunnel junctions with an in-plane easy axis with large values of perpendicular magnetic anisotropy. The group deliberately used a flat magnetic easy axis to achieve shorter relaxation times.
Designed by MTJ is compatible with current processesprocessing semiconductors and shows significant prospects for the future implementation of high-performance probabilistic computers. This theoretical basis for the dynamics of magnetization, including entropy, is also of broad scientific importance, ultimately showing the potential of spintronics in solving controversial issues in statistical physics.
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