Structural Analysis of Quantum Turbo Codes

ing is that a quantum convolutional encoder cannot simultaneously be recursive and non-catastrophic. These properties are necessary for quantum turbo code to have aminimum distance growing with block length and for their iterative decoding algorithm to converge. The entanglementassisted method can simplifies the theory of quantum turbo codes. Therefore, an entanglement-assisted quantum convolutional encoder can possess both of the aforementioned desirable properties. Also, the quantum turbo decoding algorithm can be changed in order to have the constituent decoders pass along only extrinsic information to each other. This leads to a significant improvement in the performance of unassisted quantum turbo codes. Entanglement-assisted turbo codes can operate reliably in a noise region beyond that of standard quantum turbo codes. With some modification in the quantum turbo code structure, it can have both a growing minimum distance and the iterative decoding algorithmconverging. One way is based on allowing the sender and the receiver access to shared entanglement before communication begins.

Keywords:

Quantum communication , Turbo code , Error correction , Quantum convolutional code