内容：

We propose to encode a quantum bit of information in a superposition of coherent states of an oscillator,

with four different phases. Our encoding in a single cavity mode, together with a protection protocol,

significantly reduces the error rate due to photon loss. This protection is ensured by an efficient quantum

error correction scheme employing the nonlinearity provided by a single physical qubit coupled to the

cavity. We describe in detail how to implement these operations in a circuit quantum electrodynamics

system. This proposal directly addresses the task of building a hardware-efficient quantum memory and

can lead to important shortcuts in quantum computing architectures.