ABSTRACT
Cloud services are being acknowledged as the method for providing access to quantum processing. Rather than storing and processing data on a local server, the data storing and processing are done on cloud infrastructures like a public, private or hybrid cloud. Recently, the cloud has enabled the storage and processing of quantum information that exists in different quantum states. Noise is a great bane of information processing systems. A major challenge for the future of quantum computation and quantum information is to provide distributed quantum computation in a reliable manner. Normally encoding and decoding of quantum information is done to protect a message against the effects of noise. Error detection codes can detect the noise but cannot provide reliability, that is, the initial state of the quantum information cannot be recovered. This chapter discusses a two-level error correcting code to achieve reliability of quantum information that is stored in cloud infrastructures. In the first level, error-detection or syndrome diagnosis is performed that measures the error syndrome on the quantum state, if occurred. The syndrome measurement contains only the information about what error has occurred, and it does not know anything about the state that is protected. In the second level, the recovery procedure is performed and it acts on the value of the error syndrome to recover the initial state. This procedure can improve the reliability of storage of the quantum state in the cloud with a maximum possible probability.
