Abstract. We propose a scheme for the realization of artificial neural networks based on Superconducting Quantum Interference Devices (SQUIDs). In order to demonstrate the operation of this scheme we designed and successfully tested a small network that implements a XOR gate and is trained by means of examples. The proposed scheme can be particularly convenient as support for superconducting applications such as detectors for astrophysics, high energy experiments, medicine imaging and so on.
Artificial Neural NetworksArtificial Neural Networks (ANN) are a computing paradigm inspired by biological neural systems [1,2]. They are particularly effective in specific tasks such as pattern recognition, data mining, regression and analysis of series, classification, filtering and so on. An important characteristic of ANN is their capability to learn and to be trained in order to perform some required task. The training can be done once and for all during an initial preparatory phase (which can also be the design phase) if the network is used only for recurrent tasks, or it is possible to have a network that can learn during its use, in order to adapt itself to a changing environment. ANN can be realized in many different ways according to the needs of specific applications: for example they can be simulated by computer programs, or implemented by discrete electronic circuits, by microcontrollers, DSPs, ASICs and so on [3,4]. Unconventional electronics can also be used for this task, for example there are different proposals based on the use of superconducting electronics [5][6][7][8]. Superconducting electronics allows computing speeds not possible with conventional semiconductor electronics (with clocks of the order of hundreds of Gigahertz) [9][10][11], but its drawback is the necessity to use cryogenic systems, with relative costs and request of competences. However there are different examples of important existing applications based on low temperatures and superconductivity (astrophysical detectors, medical imaging, high energy physics, quantum communication and computing, ultra low noise electronics, metrology and so on) where the introduction of a superconducting electronics is not cause of extra cost, but rather it could provide a natural interface between the superconducting system and the room temperature electronics, performing preliminary tasks such as multiplexing, pre-analysis and triggering [12][13][14][15]. In many cases the availability of a fast superconducting ANN close to the system could be a very useful and desirable tool.In the present work we consider a simple and flexible scheme for the realization of ANNs with SQUIDs (Superconducting Quantum Interference Devices), a widely used class of superconducting devices characterized by outstanding performances as ultrasensitive magnetometers and low noise amplifiers [16][17][18]. In order to prove the operation of the proposed scheme we realized and tested a