Monday, July 29, 2013

1307.6970 (Tetsufumi Tanamoto)

Implementation of standard quantum error correction codes for
solid-state qubits

Tetsufumi Tanamoto
In quantum error-correcting code (QECC), many quantum operations and measurements are necessary to correct errors in logical qubits. In the stabilizer formalism, which is widely used in QECC, generators $G_i (i=1,2,..)$ consist of multiples of Pauli matrices and perform encoding, decoding and measurement. In order to maintain encoding states, the stabilizer Hamiltonian $H_{\rm stab}=-\sum_i G_i$ is suitable because its ground state corresponds to the code space. On the other hand, Hamiltonians of most solid-state qubits have two-body interactions and show their own dynamics. In addition solid-state qubits are fixed on substrate and qubit-qubit operation is restricted in their neighborhood. The main purpose of this paper is to show how to directly generate the stabilizer Hamiltonian $H_{\rm stab}$ from conventional two-body Hamiltonians with Ising interaction and XY interaction by applying a pulse control method such as an NMR technique. We show that generation times of $H_{\rm stab}$ for nine-qubit code, five-qubit code and Steane code are estimated to be less than 300 ns when typical experimental data of superconducting qubits are used, and sufficient pulse control is assumed. We also show how to prepare encoded states from an initial state $|0....0>$. In addition, we discuss an appropriate arrangement of two- or three-dimensional arrayed qubits.
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