Quantum state transfer and time-dependent disorder in quantum chains
Institute of Theoretical Computer Science, ETH Zurich, 8092 Zurich, Switzerland
One of the most basic tasks required for Quantum Information Technology is the ability to connect different components of a Quantum Computer by quantum wires that obey the superposition principle. Since superpositions can be very sensitive to noise this turns out to be already quite difficult. Recently, it was suggested to use chains of permanently coupled spin-1/2 particles (quantum chains) for this purpose. They have the advantage that no external control along the wire is required during the transport of information, which makes it possible to isolate the wire from sources of noise. We first give an introduction to basic quantum state transfer and review existing advanced schemes by other authors. We then show a new result that demonstrates the stability of the scheme  against disorder that is approximately constant during one application of the channel, but time-dependent with respect to multiple applications.
© EDP Sciences, Springer-Verlag, 2007