The transfer learning of a neural network is one of its most outstanding aspects, and has given supervised learning with neural networks a prominent place in data science. Here we explore this feature in the context of strongly interacting many-body systems. By means of case studies, we show the potential of this deep learning technique to detect phases and their transitions in frustrated spin systems, using dense and convolutional neural networks. In addition, we explore a recently-introduced technique, which is at the middle point of supervised and unsupervised learning. It consists in evaluating the performance of a neural network which has been deliberately 'confused' during its training. To properly demonstrate the capability of the 'confusion' and transfer learning techniques, we apply them to a paradigmatic model of frustrated magnetism in two dimensions, to determine its phase diagram and compare it with high-performance Monte Carlo simulations.
Abstract The minimal training set to train a working convolutional neural network (CNN) is explored in detail. The model under consideration is the frustrated
J1-
J2 Ising model on the square lattice. Here
J1<0 and
J2>0 are the nearest and next-to-nearest neighboring couplings, respectively. We train the CNN using the configurations of
g=defJ2/∣J1∣=0.7 and employ the resulting CNN to study the phase transition of
g=0.8. We find that this transfer learning is successful. In particular, only configurations of two temperatures, one below and one above the critical temperature
Tc of
g=0.7, are needed to accurately determine the
Tc of
g=0.8. However, it may be subtle to use this strategy for the training. Specifically, for the model under consideration, due to the inefficiency of the single spin-flip algorithm used in sampling the configurations in the low-temperature region, the two temperatures associated with the training set should not be too far away from the
Tc of
g=0.7. Otherwise, the performance of the obtained CNN is not of high quality, and hence cannot determine the
Tc of
g=0.8 accurately. For the model under consideration, we also uncover the condition for training a successful CNN when only configurations of two temperatures are considered as the training set.
The authors describe a method for determining the critical point of a second order phase transitions using a convolutional neural network based on the Ising model on a square lattice. Data for training and analysis were obtained using Monte Carlo simulations. The neural network was trained on the data corresponding to the low-temperature phase, that is a ferromagnetic one and high-temperature phase, that is a paramagnetic one, respectively. After training, the neural network analyzed input data from the entire temperature range: from 0.1 to 5.0 (in dimensionless units J) and determined the Curie point Tc.