  In this article, we present the unbalanced quantum error correcting
codes(one-party-QECC), a novel idea for correcting unbalanced quantum errors.
In some quantum communication tasks using entangled pairs, the error
distributions between two parts of the pairs are unbalanced, and. one party
holds the whole entangled pairs at the final stage, and he or she is able to
perform joint measurements on the pairs. In this situation the proposed
one-party-QECC can improve error correction by allowing a higher tolerated
error rate. We have established the general correspondence between linear
classical codes and the one-party-QECC, and we have given the general
definition for this type quantum error correcting codes.It has been shown that
the one-party-QECC can correct errors as long as the error threshold is not
larger than 0.5. The one-party-QECC works even for fidelity less than 0.5 as
long as it is larger than 0.25. We give several concrete examples of the
one-party-QECC. We provide the applications of one-party-QECC in quantum dense
coding so that it can function in noisy channels. As a result, a large number
of quantum secure direct communication protocols based on dense coding is also
able to be protected by this new type of one-party-QECC.
