Distinguishing Schrödinger cats in a lossy environment
A. Gábris, Петер Адам, Mátyás Koniorczyk, József Janszky · Journal of Optics B Quantum and Semiclassical Optics · 2004
Optical Schrödinger cat states—that is, even and odd coherent states—are considered as possible candidates for forming a computational basis for a coherent state qubit. The distinguishability of the two originally orthogonal states after experiencing loss is quantified in terms of quantum relative entropy. This is a physically instructive quantity related to probabilities of faults in identifying the state. This distinguishability is important for classical communication and for the problem of reading out the result of a quantum computation by a lossy device. It is shown that the distinguishability can significantly increase if the environment is prepared in an appropriately chosen squeezed state.