Fig. 2: Building blocks for a generic QQBF.
From: Modular quantum-to-quantum Bernoulli factory in an integrated photonic processor
Interferometric schemes that implement the basic operations to build a generic QQBF with dual-rail encoded qubits are shown. The inputs of the interferometers are labelled by numbers 1 and 2, and the outputs are labelled as ‘o’. a, Inversion operation is performed by swapping the two modes of the input dual-rail qubit. b, Product operation is performed by sending one waveguide from each dual-rail qubit (|1〉1 and |0〉2) into a balanced BS, and measuring the outgoing modes. Detection of a single photon in the modes labelled ‘+’ or ‘–’ signals success (up to a global phase). c, Addition operation is implemented by directing the modes, representing the same state of the two qubits, to equally unbalanced BSs, and measuring one output mode for each BS. When one photon is found in the detector labelled S, and the other photon is in output mode |0〉o or |1〉o, the output state is the sum of the input ones (up to a global phase).
