Efficient noiseless linear amplification for light fields with larger amplitudes

We suggest and investigate a scheme for non-deterministic noiseless linear amplification of coherent states using successive photon addition, ((a) over cap dagger)(2), where (a) over cap dagger is the photon creation operator. We compare it with a previous proposal using the photon addition-then-subtraction, (a) over cap(a) over cap dagger, where (a) over cap is the photon annihilation operator, that works as an appropriate amplifier only for weak light fields. We show that when the amplitude of a coherent state is |alpha| greater than or similar to 0.91, the ((a) over cap dagger)(2) operation serves as a more efficient amplifier compared to the (a) over cap(a) over cap dagger operation in terms of equivalent input noise. Using (a) over cap(a) over cap dagger and ((a) over cap dagger)(2) as basic building blocks, we compare combinatorial amplifications of coherent states using ((a) over cap(a) over cap dagger)(2), (a) over cap dagger(4), (a) over cap(a) over cap dagger(a) over cap dagger(2), and (a) over cap dagger(2)(a) over cap(a) over cap dagger, and show that ((a) over cap(a) over cap dagger)(2), (a) over cap dagger(2)(a) over cap(a) over cap dagger, and (a) over cap dagger(4) exhibit strongest noiseless properties for |alpha| less than or similar to 0.51, 0.51 less than or similar to |alpha| less than or similar to 1.05, and |alpha| greater than or similar to 1.05, respectively. We further show that the ((a) over cap dagger)(2) operation can be useful for amplifying superpositions of the coherent states. In contrast to previous studies, our work provides efficient schemes to implement a noiseless amplifier for light fields with medium and large amplitudes. (C) 2016 Optical Society of America