Models of reduced-noise, probabilistic linear amplifiers

Abstract

We construct an amplifier that interpolates between a nondeterministic, immaculate linear amplifier and a deterministic, ideal linear amplifier and beyond to nonideal linear amplifiers. The construction involves cascading an immaculate linear amplifier that has amplitude gain g1 with a (possibly) nonideal linear amplifier that has gain g2. With respect to normally ordered moments, the device has output noise µ 2 (G 2−1) where G = g1g2 is the overall amplitude gain and µ 2 is a noise parameter. When µ 2 ≥ 1, our devices realize ideal (µ 2 = 1) and nonideal (µ 2 > 1) linear amplifiers. When 0 ≤ µ 2 < 1, these devices work effectively only over a restricted region of phase space and with some subunity success probability pX. We investigate the performance of our µ 2 -amplifiers in terms of a gain-corrected probability-fidelity product and the ratio of input to output signal-to-noise ratios corrected for success probability.