Quantum Inf Process (2016) 15:2553–2568
Evaluation of the performance of two state-transfer
Hamiltonians in the presence of static disorder
A. K. Pavlis
· G. M. Nikolopoulos
Received: 22 September 2015 / Accepted: 23 February 2016 / Published online: 18 March 2016
© Springer Science+Business Media New York 2016
Abstract We analyze the performance of two quantum-state-transfer Hamiltonians in
the presence of diagonal and off-diagonal disorders, and in terms of different measures.
The ﬁrst Hamiltonian pertains to a fully engineered chain, and the second to a chain
with modiﬁed boundary couplings. The task is to ﬁnd which Hamiltonian is the most
robust to given levels of disorder and irrespective of the input state. In this respect, it
is shown that the performances of the two protocols are approximately equivalent.
Keywords State transfer · Quantum communication · Spin chains
Over the last decade, the problem of state transfer and the engineering of quantum
networks have evolved into one of the most active research areas of quantum tech-
nologies. Various faithful state-transfer Hamiltonians (protocols) have been proposed,
and networks of various topologies have been analyzed .
Among the proposed Hamiltonians, those with permanently coupled sites have a
prominent position as they require no dynamical manipulations for the transfer .
Such state-transfer Hamiltonians have the potential of providing passive quantum
networks that perform certain communication tasks, without the need of external
control (besides the preparation and the read-out of the input state). In that context,
the simplest problem one may consider pertains to the faithful (ideally perfect) transfer
of a single-qubit state between the two ends of a spin chain with permanently coupled
G. M. Nikolopoulos
Institute of Electronic Structure & Laser, FORTH, P.O. Box 1385, 70013 Heraklion, Greece
Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion, Crete, Greece