211 research outputs found
End-to-end entanglement in Bose-Hubbard chains
We study the ground state as well as the dynamics of chains of bosons with
local repulsive interactions and nearest-neighbour exchange using numerical
techniques based on density matrix decimation. We explore the development of
entanglement between the terminal sites of such chains as mechanisms are
invoked to concentrate population in these sites. We find that long-range
entanglement in the ground state emerges as a result of hopping taking place at
the whole chain length in systems with appropriate hopping coefficients.
Additionally, we find appropriate perturbations to increase the entanglement
between the end sites above their ground state values.Comment: 7 pages, 8 figure
Quantum Gates Between Two Spins in a Triple Dot System with an Empty Dot
We propose a scheme for implementing quantum gates and entanglement between
spin qubits in the outer dots of a triple-dot system with an empty central dot.
The voltage applied to the central dot can be tuned to realize the gate. Our
scheme exemplifies the possibility of quantum gates outside the regime where
each dot has an electron, so that spin-spin exchange interaction is not the
only relevant mechanism. Analytic treatment is possible by mapping the problem
to a t-J model. The fidelity of the entangling quantum gate between the spins
is analyzed in the presence of decoherence stemming from a bath of nuclear
spins, as well as from charge fluctuations. Our scheme provides an avenue for
extending the scope of two qubit gate experiments to triple-dots, while
requiring minimal control, namely that of the potential of a single dot, and
may enhance the qubit separation to ease differential addressability.Comment: 7 pages, 6 figure
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