TY - JOUR
T1 - Preparation of decoherence-free cluster states with optical superlattices
JF - Physical Review A (Atomic, Molecular, and Optical Physics)
Y1 - 2009
A1 - Jiang, Liang
A1 - Rey, Ana Maria
A1 - Romero-Isart, Oriol
A1 - Garcia-Ripoll, Juan Jose
A1 - Sanpera, Anna
A1 - Lukin, Mikhail D.
KW - atom-photon collisions
KW - ground states
KW - optical multilayers
KW - quantum optics
KW - superlattices
VL - 79
UR - http://link.aps.org/abstract/PRA/v79/e022309 http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PLRAAN000079000002022309000001&idtype=cvips&gifs=yes http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PLRAAN000079000002
ER -
TY - JOUR
T1 - Quantum information processing in spin chains via quantum Zeno dynamics
JF - arXiv
Y1 - 2008
A1 - Monras, Alex
A1 - Romero-Isart, Oriol
KW - spin chain
AB - We show how the quantum Zeno effect can be exploited to control quantum information in a spin chain in a flexible way. In particular, we consider a one dimensional array of three level systems interacting via a swap operator, an interaction found in a generalized Heisenberg Hamiltonian. By encoding the qubit into two levels and using simple projective frequent measurements, the dynamics of the chain is guided to achieve basic quantum information manipulation tools, $\backslash$emph\{i.e.\}, quantum registers, single qubit operations and quantum state transfer on demand, while local addressability is not required. State transfer is perfect, robust against errors and delivers qubits at a constant rate, unconditional of the length of the transfer. Moreover, two dimensional lattices with tunable global interactions in different directions offer the possibility of performing two-qubit gates.
UR - http://arxiv.org/abs/0801.1959
ER -
TY - JOUR
T1 - Quantum non-demolition detection of strongly correlated systems
JF - Nature Physics
Y1 - 2008
A1 - Eckert, Kai
A1 - Romero-Isart, Oriol
A1 - Rodriguez, Mirta
A1 - Lewenstein, Maciej
A1 - Polzik, Eugene S.
A1 - Sanpera, Anna
VL - 4
UR - http://www.nature.com/nphys/journal/v4/n1/full/nphys776.html
ER -
TY - JOUR
T1 - Efficiency in Quantum Key Distribution Protocols with Entangled Gaussian States
JF - Open Systems & Information Dynamics
Y1 - 2007
A1 - Rodó, Carles
A1 - Romero-Isart, Oriol
A1 - Eckert, Kai
A1 - Sanpera, Anna
KW - gaussian states
KW - quantum cryptography
KW - quantum key distribution
AB - Abstract Quantum key distribution (QKD) refers to specific quantum strategies which permit the secure distribution of a secret key between two parties that wish to communicate secretly. Quantum cryptography has proven unconditionally secure in ideal scenarios and has been successfully implemented using quantum states with finite (discrete) as well as infinite (continuous) degrees of freedom. Here, we analyze the efficiency of QKD protocols that use as a resource entangled gaussian states and gaussian operations only. In this framework, it has already been shown that QKD is possible [1] but the issue of its efficiency has not been considered. We propose a figure of merit (the efficiency E) to quantify the number of classical correlated bits that can be used to distill a key from a sample of N entangled states. We relate the efficiency of the protocol to the entanglement and purity of the states shared between the parties.
VL - 14
UR - http://dx.doi.org/10.1007/s11080-007-9030-x
ER -
TY - JOUR
T1 - Efficient quantum-state transfer in spin chains via adiabatic passage
JF - New Journal of Physics
Y1 - 2007
A1 - Eckert, Kai
A1 - Romero-Isart, Oriol
A1 - Sanpera, Anna
KW - spin chain
KW - state transfer
VL - 9
UR - http://iopscience.iop.org/1367-2630/9/5/155/pdf/1367-2630\_9\_5\_155.pdf
ER -
TY - JOUR
T1 - Quantum ratchets for quantum communication with optical superlattices
JF - Physical Review A (Atomic, Molecular, and Optical Physics)
Y1 - 2007
A1 - Romero-Isart, Oriol
A1 - Garcia-Ripoll, Juan Jose
KW - atom-photon collisions
KW - optical modulation
KW - quantum entanglement
KW - quantum optics
KW - superlattices
VL - 76
UR - http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PLRAAN000076000005052304000001&idtype=cvips&prog=normal
ER -
TY - JOUR
T1 - Quantum state transfer in spin-1 chains
JF - Physical Review A (Atomic, Molecular, and Optical Physics)
Y1 - 2007
A1 - Romero-Isart, Oriol
A1 - Eckert, Kai
A1 - Sanpera, Anna
KW - ferromagnetic materials
KW - ground states
KW - Heisenberg model
KW - magnetic transitions
KW - quantum entanglement
KW - spin chain
KW - spin systems
KW - state transfer
VL - 75
UR - http://link.aps.org/abstract/PRA/v75/e050303
ER -
TY - JOUR
T1 - Transport and entanglement generation in the Bose-Hubbard model
JF - Journal of Physics A: Mathematical and General
Y1 - 2007
A1 - Romero-Isart, Oriol
A1 - Eckert, Kai
A1 - Rodó, Carles
A1 - Sanpera, Anna
VL - 40
UR - http://www.iop.org/EJ/article/1751-8121/40/28/S11/a7\_28\_s11.pdf
ER -
TY - JOUR
T1 - Separable Measurement Estimation of Density Matrices and its Fidelity Gap with Collective Protocols
JF - Physical Review Letters
Y1 - 2006
A1 - Bagan, Emili
A1 - Ballester, M. A.
A1 - Gill, R. D.
A1 - Muñoz-Tapia, Ramon
A1 - Romero-Isart, Oriol
KW - mixed states
KW - state estimation
VL - 97
UR - http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000097000013130501000001&idtype=cvips&gifs=yes
ER -
TY - JOUR
T1 - Purity Estimation with Separable Measurements
JF - Physical Review Letters
Y1 - 2005
A1 - Bagan, Emili
A1 - Ballester, M. A.
A1 - Muñoz-Tapia, Ramon
A1 - Romero-Isart, Oriol
AB - Given a large number N of copies of a qubit state of which we wish to estimate its purity, we prove that separable-measurement protocols can be as efficient as the optimal joint-measurement one if classical communication is used. This shows that the optimal estimation of the entanglement of a two-qubit state can also be achieved asymptotically with fully separable measurements. Thus, quantum memories provide no advantage in this situation. The relationship between our global Bayesian approach and the quantum Cramér-Rao bound is discussed.
PB - American Physical Society
VL - 95
UR - http://link.aps.org/doi/10.1103/PhysRevLett.95.110504
ER -