Fig. 2: Schematic of experiment and simplified chip layout.
From: Integrated photonic source of Gottesman–Kitaev–Preskill qubits
A series of pump and reference laser fields are sent over fibre to the input of an optically and electrically packaged chip. The strong classical fields are filtered and distributed (1) to an array of four squeezers based on a two-resonator photonic molecule design (2). The generated pulsed, nearly single-temporal-mode, squeezed vacuum states are separated from the pump laser light by on-chip optical filters (3), before being entangled by a programmable linear interferometer or unitary (4). Another array of integrated filters further suppresses the pump light (5). Three of the optical modes are sent to PNR detectors that, when the correct detection pattern is observed, herald the production of a GKP qubit state in the remaining optical mode, which is then analysed using homodyne detection (HD).
