449 research outputs found
Iterative quantum state transfer along a chain of nuclear spin qubits
Transferring quantum information between two qubits is a basic requirement
for many applications in quantum communication and quantum information
processing. In the iterative quantum state transfer (IQST) proposed by D.
Burgarth et al. [Phys. Rev. A 75, 062327 (2007)], this is achieved by a static
spin chain and a sequence of gate operations applied only to the receiving end
of the chain. The only requirement on the spin chain is that it transfers a
finite part of the input amplitude to the end of the chain, where the gate
operations accumulate the information. For an appropriate sequence of
evolutions and gate operations, the fidelity of the transfer can asymptotically
approach unity. We demonstrate the principle of operation of this transfer
scheme by implementing it in a nuclear magnetic resonance quantum information
processor.Comment: Version for submission. Comments are welcom
Effect of system level structure and spectral distribution of the environment on the decoherence rate
Minimizing the effect of decoherence on a quantum register must be a central
part of any strategy to realize scalable quantum information processing. Apart
from the strength of the coupling to the environment, the decoherence rate is
determined by the the system level structure and by the spectral composition of
the noise trace that the environment generates. Here, we discuss a relatively
simple model that allows us to study these different effects quantitatively in
detail. We evaluate the effect that the perturbation has on an NMR system while
it performs a Grover search algorithm.Comment: Generalizations are added. Comments are welcom
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