Quantum state comparison amplifier with feedforward state correction
Luca Mazzarella, Ross J. Donaldson, Robert John Collins, Ugo Zanforlin, Gioan Tatsi, Gerald S. Buller, John R. Jeffers · 2018
Quantum mechanics imposes stringent constraints on the amplification of a quantum signal. Deterministic amplification of an unknown quantum state always implies the addition of a minimal amount of noise. Linear and noiseless amplification is allowed in principle provided that it only works probabilistically. Here we present a probabilistic amplifier that combines two quantum state comparison amplifiers (SCAMP) together with a feed-forward state correction strategy. Our system outperforms the unambiguous state discrimination (USD) measure-and-resend based amplifier in terms of the success probability-fidelity product and requires a more complex experimental setting.