Apparatus and methods for quantum computing and machine learning

A method, comprising:

• propagating an input signal through a plurality of processing layers connected in series, the input signal including a plurality of optical modes, the propagation of the input signal through the plurality of processing layers includes:
• performing a linear transformation on the plurality of optical modes using a Gaussian unit that includes:
• a network of interconnected beamsplitters and phase shifters;
• and
• a plurality of squeezers operatively coupled to the network of interconnected beamsplitters and phase shifters;
• and
• performing a nonlinear transformation on the plurality of optical modes using a plurality of nonlinear gates;
• and
• sending an output signal from the plurality of processing layers.

A reconfigurable computing device, comprising:

• a plurality of processing layers coupled in series and configured to receive an input signal including a plurality of optical modes, each processing layer in the plurality of processing layers including:
• a Gaussian unit configured to perform a linear transformation on the plurality of optical modes, the Gaussian unit including:
• a network of interconnected beamsplitters and phase shifters;
• a plurality of squeezers operatively coupled to the network of interconnected beamsplitters and phase shifters;
• and
• a plurality of displacers operatively coupled to the plurality of squeezers and the network of interconnected beamsplitters and phase shifters;
• and
• a plurality of nonlinear gates configured to perform a nonlinear transformation over the plurality of optical modes;
• and
• a controller operatively coupled to the plurality of processing layers and configured to switch the apparatus between a first mode to implement a classical neural network, a second mode to implement a quantum computation, and a third mode to implement a quantum neural network,
• during the first mode:
• a first portion of the network of interconnected beamsplitters and phase shifters being configured to form a first interferometer to apply a first phase-less transformation on the plurality of optical modes,
• the plurality of squeezers being configured to apply a position-only squeezing to the plurality of optical modes,
• a second portion of the network of interconnected beamsplitters and phase shifters being configured to form a second interferometer to apply a second phase-less transformation on the plurality of optical modes,
• the plurality of displacers being configured to apply a position-only displacement to the plurality of optical modes, and
• the plurality of nonlinear gates being configured to apply the nonlinear transformation between a first set of position eigenstates and a second set of position eigenstates of the plurality of optical modes,
• during the second mode:
• at least one of the Gaussian unit or the plurality of nonlinear gates is configured to create an entanglement or a superposition in the plurality of optical modes,
• during the third mode:
• at least one of the Gaussian unit or the plurality of nonlinear gates is configured to create the entanglement or the superposition in the plurality of optical modes, and
• the controller is configured to change a setting of the plurality of processing layers based on an output signal from the plurality of processing layers.