30 research outputs found
Universal feedback control of two-qubit entanglement
We consider two-qubit undergoing local dissipation and subject to local
driving. We then determine the optimal Markovian feedback action to preserve
initial entanglement as well as to create stationary entanglement with the help
of an XY interaction Hamiltonian. Such feedback actions are worked out in a way
not depending on the initial two-qubit state, whence called universal.Comment: 10 pages, 6 figure
The entangling power of a "glocal" dissipative map
We consider a model of two qubits dissipating into both local and global
environments (generally at non-zero temperatures), with the possibility of
interpolating between purely local dissipation and purely global one. The
corresponding dissipative dynamical map is characterized in terms of its Kraus
operators focusing on the stationary regime. We then determine conditions under
which entanglement can be induced by the action of such a map. It results
(rather counterintuitively) that in order to have entanglement in the presence
of local environment, this latter must be at nonzero temperature.Comment: 13 pages, 6 figure
Routing a quantum state in a bio-inspired network
We consider a spin network resembling an -helix structure and study
quantum information transfer over this bio-inspired network. The model we use
is the Davydov model in its elementary version without a phononic environment.
We investigate analytically and numerically the perfect state transfer (PST) in
such a network which provides an upper bound on the probability of quantum
states transfer from one node to another. We study PST for different boundary
conditions on the network and show it is reachable between certain nodes and
with suitable spin-spin couplings.Comment: 12 pages, 5 figure
Enforcing dissipative entanglement by feedback
We study the possibility of enhancing the stationary entanglement achievable with two-qubit dissipating into a common environment by means of feedback. We contrast the effect of Markovian with Bayesian feedback and show that, depending on the initial state, the performance of the latter is from 16% to 33% superior