An exact
effective two-qubit gate in a chain of three spins
(pp174-185)
M.-H. Yung, D.W. Leung, and S.
Bose
doi:
https://doi.org/10.26421/QIC4.3-2
Abstracts:
We show that an effective two-qubit gate can be obtained
from the free evolution of three spins in a chain with nearest neighbor
XY coupling, without local manipulations. This gate acts on the two
remote spins and leaves the mediating spin unchanged. It can be used to
perfectly transfer an arbitrary quantum state from the first spin to the
last spin or to simultaneously communicate one classical bit in each
direction. One ebit can be generated in half of the time for state
transfer. For longer spin chains, we present methods to create or
transfer entanglement between the two end spins in half of the time
required for quantum state transfer, given tunable coupling strength and
local magnetic field. We also examine imperfect state transfer through a
homogeneous XY chain.
Key words:
spin chain, quantum gate, state tansfer, entanglement |