Parity-swap state comparison amplifier for Schrödinger cat states

Abstract

We propose a postselecting parity-swap amplifier for Schrödinger cat states that does not require the amplified state to be known a priori. The device is based on a previously-implemented state comparison amplifier for coherent states. It consumes only Gaussian resource states, which provides an advantage over some cat state amplifiers. It requires simple Geiger-mode photodetectors and works with high fidelity and approximately twofold gain.

Multi-headed symmetrical superpositions of coherent states

“…Using Eq (8), we list a † , a , a † a , a †2 , a 2 , and a †2 a 2 for NHCSS in table II. Some expressions of a † a and a †2 a 2 in Table II, which are related to |α| but not θ p , haven't been given yet because of their complexity.…”

“…For instance, the Schrodinger cat state is a superposition of two coherent states with coherent amplitudes of the same magnitude but different phases [7]. Moreover, the Schrodinger cat state can exhibit different nonclassical properties having foundational applications in quantum information processing [8,9].…”