Automated error correction in superdense coding, with implementation on
  superconducting quantum computer
Construction of a fault-tolerant quantum computer remains a challenging
problem due to unavoidable noise in quantum states and the fragility of quantum
entanglement. However, most of the error-correcting codes increases the
complexity of the algorithms, thereby decreasing any quantum advantage. Here we
present a task-specific error-correction technique that provides a complete
protection over a restricted set of quantum states. Specifically, we give an
automated error correction in Superdense Coding algorithms utilizing n-qubit
generalized Bell states. At its core, it is based on non-destructive
discrimination method of Bell states involving measurements on ancilla qubits
(phase and parity ancilla). The algorithm is shown to be distributable and can
be distributed to any set of parties sharing orthogonal states. Automated
refers to experimentally implementing the algorithm in a quantum computer by
utilizing unitary operators with no measurements in between and thus without
the need for outside intervention. We also experimentally realize our automated
error correction technique for three different types of superdense coding
algorithm on a 7-qubit superconducting IBM quantum computer and also on a
27-qubit quantum simulator in the presence of noise. Probability histograms are
generated to show the high fidelity of our experimental results. Quantum state
tomography is also carried out with the quantum computer to explicate the
efficacy of our method.
Kumar Nilesh Piyush Joshi Prasanta Panigrahi