Globally controlled quantum wires for perfect qubit transport, mirroring and computing

Abstract

It is expected that quantum wires (q-wires), will be required to transport quantum information within many quantum computer implementations. Here we describe a new design for a q-wire with perfect transmission using a uniformly coupled Ising spin chain subject to global (homogeneously-applied) pulses. Besides allowing for perfect transport of single qubits, the design also yields the perfect ``mirroring'' of multiply encoded qubits within the wire. We further utilise this global-pulse generated perfect mirror operation as a ``clock cycle'' to perform universal quantum computation on these multiply encoded qubits. We demonstrate the operation of single and two-qubit quantum logic gates and show that only $N-1$ complete mirror cycles are required to execute a quantum Fourier transform on $N$ qubits encoded within the q-wire.