Overcoming the classical signal-to-noise ratio limit through on-chip photon addition

Single-photon addition enables “lossless” amplification and preparation of non-Gaussian and arbitrary quantum states using nonlinear optical processes and tabletop optics. While photon addition can be implemented in free space using bulk optics, often these discrete components can lead to compounded input and output losses, which detract from amplification. Furthermore, arbitrary quantum states are an essential resource for photonic quantum computing, which will be more accessible if created on-chip. We present a conceptual chip-based device for deterministic single-photon addition and integrated superconducting nanowire-based detection, with a focus on how this device facilitates “lossless” amplification in phase-based interferometry. Our model using on-chip, deterministic photon addition overcomes the classical signal-to-noise ratio (SNR) limits of coherent and thermal light by 2.3× and 3.5×, respectively. These gains increase with additional single-photon addition events. Through careful device design and optimization, we limit total system loss to −1.15 dB. We estimate this device could produce a waveguide-coupled deterministic single-photon in 21% of pulsed signals, far outperforming the probability rates of probabilistic sources. Finally, we show that the benefits of on-chip, deterministic single-photon addition for SNR amplification outweigh chip input losses.