Luis Roa - Academia.edu (original) (raw)
Papers by Luis Roa
We study the stability of the coherence of a state of a quantum system under the effect of an int... more We study the stability of the coherence of a state of a quantum system under the effect of an interaction with another quantum system at short time. We find an expression for evaluating the order of magnitude of the time scale for the onset of instability as a function of the initial state of both involved systems and of the sort of interaction between them. As an application we study the spin-boson interaction in the dispersive interaction regime, driven by a classical field. We find, for this model, that the behavior of the time scale for the onset of instability, with respect to the boson bath temperature, changes depending on the intensity of the classical field.
Tetrahedron Asymmetry, 2004
A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-h... more A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium iodide 1 and 2 to generate (3R,5S)-5-methyl- and (3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridine 3 and 4, respectively, is reported. In addition, an enantioselective synthesis of (−)-(2R,6S)-dihydropinidine and (+)-(2S,6S)-indolizidine 167B starting from 3 and 4, respectively, was achieved.(2S,6R)-1-[(1′R)-2′-Hydroxy-1′-phenylethyl]-2-methyl-6-propylpiperidineC17H27NO[α]D20=-17 (c 1.5, EtOH)(2S,6S)-2′-[2-(2-[1,3]Dioxolan-2-yl-ethyl)-6-propylpiperidin-1-yl]-1′(R)-phenyl-ethanolC21H33NO3[α]D20=+40 (c 1.0, EtOH)
Acta Crystallogr E Struct Rep, 2003
ABSTRACT
We study the teleportation scheme performed by means of a partially entangled pure state. We foun... more We study the teleportation scheme performed by means of a partially entangled pure state. We found that the information belonging to the quantum channel can be distributed into both the system of the transmitter and the system of the receiver. Thus, in order to complete the teleportation process it is required to perform an "unambiguous non-orthogonal quantum states discrimination" and an "extraction of the quantum information" processes. This general scheme allows one to design a strategy for concealing the unknown information of the teleported state. Besides, we showed that the teleportation and the "concealing the quantum information" process, can be probabilistically performed even though the bipartite quantum channel is maximally entangled.
Acta Crystallographica Section E Crystallographic Communications, 2015
The crystal structures of the two title piperidine derivatives show different conformations for t... more The crystal structures of the two title piperidine derivatives show different conformations for the six-membered heterocycle. The N-substituted 4-piperidinone 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one, C13H17NO2, (I), has a chair conformation, while the piperidine substituted in position 2 with a thio-carbonyl group, 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione, C15H19NO2S, (II), features a half-chair conformation. Comparison of the two structures, and data retrieved from the literature, suggests that the conformational flexibility is mainly related to the hybridization state of the C atom α to the piperidinic N atom: a Csp (3) atom favours the chair conformer, while a Csp (2) atom distorts the ring towards a half-chair conformer. In the crystal structure of (I), weak C-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains propagating along the b-axis direction. In the crystal of (II), the mol-ecules are linked by weak C-H⋯S contacts into supra-molecular chains propagating along the b-axis direction.
Optics Communications, 2009
Entanglement concentration for higher dimensional quantum systems, qudits, is studied. In particu... more Entanglement concentration for higher dimensional quantum systems, qudits, is studied. In particular, we study a concentration protocol based on entanglement swapping of non-maximally entangled qudits via quantum state discrimination. We compare this protocol to a concentration scheme based on copies of the state to be concentrated, local transformations and two-way communications. We show that the success probability of the first
EPL (Europhysics Letters), 2015
ABSTRACT We propose a measure to quantify correlations in a bipartite quantum system of two quibi... more ABSTRACT We propose a measure to quantify correlations in a bipartite quantum system of two quibits by assessing the minimum difference between outcome states of a subsystem by performing a local measurement on the other subsystem. This maximum similarity measure is a monotone function of the concurrence for pure states of two qubits; for mixed states it accounts for entanglement, dissonance, and classical correlations. Besides, we found a closed formula for evaluating the similarity degree of an arbitrary mix state of two two-dimensional systems.
Physical Review A, 2010
We have developed a general method for constructing a set of nonorthogonal bases with equal separ... more We have developed a general method for constructing a set of nonorthogonal bases with equal separations between all different basis states in prime dimensions. The results are that the corresponding biorthogonal counterparts are pairwise unbiased with the components of the original ...
International Conference on Quantum Information, 2007
Abstract We study the entanglement dynamics of two not interacting atoms coupled dispersively wit... more Abstract We study the entanglement dynamics of two not interacting atoms coupled dispersively with the same single mode. In the high energy limit there is no entanglement, the initial entanglement is as suddenly recovered as removed.
Physical Review A, 2007
... Luis Roa,1 R. Pozo-González,2,1 Marius Schaefer,1,3 and P. Utreras-SM1 1Center for Quantum Op... more ... Luis Roa,1 R. Pozo-González,2,1 Marius Schaefer,1,3 and P. Utreras-SM1 1Center for Quantum Optics and Quantum Information, Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile 2Departamento de Física, Tecnológico de Monterrey ...
Physical Review A, 2007
... Please use this identifier to cite or link to this item: http://hdl.handle.net/10533/29098\. T... more ... Please use this identifier to cite or link to this item: http://hdl.handle.net/10533/29098. Title: DRIVING A KNOWN STATE BY A DISCRETE SEQUENCE OF DIRECT MEASUREMENTS. Authors: LUIS ALBERTO ROA OPPLIGER. Keywords: AI-1030671. Issue Date: 2007. Publisher: ...
ChemInform, 2011
ABSTRACT Mixture of oxiranes (I), which are difficult to separate (no details given), allow a reg... more ABSTRACT Mixture of oxiranes (I), which are difficult to separate (no details given), allow a regiospecific synthesis of oxazepanones and morpholinones.
International Conference on Quantum Information, 2008
... 2 Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 B... more ... 2 Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte MG, Brazil. † carlos.saavedra@udec.cl Abstract: A probabilistic method for the unambiguous preparation of non-orthogonal polarization states is proposed. ...
Revista de biología marina y oceanografía, 2013
Physical Review A, 2006
We study the problem of driving an unknown initial mixed quantum state onto a known pure state wi... more We study the problem of driving an unknown initial mixed quantum state onto a known pure state without using unitary transformations. This can be achieved, in an efficient manner, with the help of sequential measurements on at least two unbiased bases. However here we found that, when the system is affected by a decoherence mechanism, only one observable is required in order to achieve the same goal. In this way the decoherence can assist the process. We show that, depending on the sort of decoherence, the process can converge faster or slower than the method implemented by means of two complementary observables. PACS numbers: 03.67.-a, 03.65.-w
Research in Optical Sciences, 2014
Arxiv preprint arXiv:0908.1686, 2009
Abstract: The task of changing the overlap between two quantum states can not be performed by mak... more Abstract: The task of changing the overlap between two quantum states can not be performed by making use of a unitary evolution only. However, by means of a unitary-reduction process it can be probabilistically modified. Here we study in detail the problem ...
Arxiv preprint quant-ph/ …, 2006
Abstract: We study the problem of driving a known initial quantum state onto a known pure state w... more Abstract: We study the problem of driving a known initial quantum state onto a known pure state without using a unitary evolution. This task can be achieved by means of von Neumann measurement processes, introducing N observables which are consecutively measured in ...
Tetrahedron: Asymmetry, 2004
A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-h... more A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium iodide 1 and 2 to generate (3R,5S)-5-methyl- and (3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridine 3 and 4, respectively, is reported. In addition, an enantioselective synthesis of (−)-(2R,6S)-dihydropinidine and (+)-(2S,6S)-indolizidine 167B starting from 3 and 4, respectively, was achieved.
We study the stability of the coherence of a state of a quantum system under the effect of an int... more We study the stability of the coherence of a state of a quantum system under the effect of an interaction with another quantum system at short time. We find an expression for evaluating the order of magnitude of the time scale for the onset of instability as a function of the initial state of both involved systems and of the sort of interaction between them. As an application we study the spin-boson interaction in the dispersive interaction regime, driven by a classical field. We find, for this model, that the behavior of the time scale for the onset of instability, with respect to the boson bath temperature, changes depending on the intensity of the classical field.
Tetrahedron Asymmetry, 2004
A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-h... more A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium iodide 1 and 2 to generate (3R,5S)-5-methyl- and (3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridine 3 and 4, respectively, is reported. In addition, an enantioselective synthesis of (−)-(2R,6S)-dihydropinidine and (+)-(2S,6S)-indolizidine 167B starting from 3 and 4, respectively, was achieved.(2S,6R)-1-[(1′R)-2′-Hydroxy-1′-phenylethyl]-2-methyl-6-propylpiperidineC17H27NO[α]D20=-17 (c 1.5, EtOH)(2S,6S)-2′-[2-(2-[1,3]Dioxolan-2-yl-ethyl)-6-propylpiperidin-1-yl]-1′(R)-phenyl-ethanolC21H33NO3[α]D20=+40 (c 1.0, EtOH)
Acta Crystallogr E Struct Rep, 2003
ABSTRACT
We study the teleportation scheme performed by means of a partially entangled pure state. We foun... more We study the teleportation scheme performed by means of a partially entangled pure state. We found that the information belonging to the quantum channel can be distributed into both the system of the transmitter and the system of the receiver. Thus, in order to complete the teleportation process it is required to perform an "unambiguous non-orthogonal quantum states discrimination" and an "extraction of the quantum information" processes. This general scheme allows one to design a strategy for concealing the unknown information of the teleported state. Besides, we showed that the teleportation and the "concealing the quantum information" process, can be probabilistically performed even though the bipartite quantum channel is maximally entangled.
Acta Crystallographica Section E Crystallographic Communications, 2015
The crystal structures of the two title piperidine derivatives show different conformations for t... more The crystal structures of the two title piperidine derivatives show different conformations for the six-membered heterocycle. The N-substituted 4-piperidinone 1-[(1R)-2-hy-droxy-1-phenyl-eth-yl]piperidin-4-one, C13H17NO2, (I), has a chair conformation, while the piperidine substituted in position 2 with a thio-carbonyl group, 8-[(1S)-1-phenyl-eth-yl]-1,4-dioxa-8-aza-spiro-[4.5]decane-7-thione, C15H19NO2S, (II), features a half-chair conformation. Comparison of the two structures, and data retrieved from the literature, suggests that the conformational flexibility is mainly related to the hybridization state of the C atom α to the piperidinic N atom: a Csp (3) atom favours the chair conformer, while a Csp (2) atom distorts the ring towards a half-chair conformer. In the crystal structure of (I), weak C-H⋯O hydrogen bonds link the mol-ecules into supra-molecular chains propagating along the b-axis direction. In the crystal of (II), the mol-ecules are linked by weak C-H⋯S contacts into supra-molecular chains propagating along the b-axis direction.
Optics Communications, 2009
Entanglement concentration for higher dimensional quantum systems, qudits, is studied. In particu... more Entanglement concentration for higher dimensional quantum systems, qudits, is studied. In particular, we study a concentration protocol based on entanglement swapping of non-maximally entangled qudits via quantum state discrimination. We compare this protocol to a concentration scheme based on copies of the state to be concentrated, local transformations and two-way communications. We show that the success probability of the first
EPL (Europhysics Letters), 2015
ABSTRACT We propose a measure to quantify correlations in a bipartite quantum system of two quibi... more ABSTRACT We propose a measure to quantify correlations in a bipartite quantum system of two quibits by assessing the minimum difference between outcome states of a subsystem by performing a local measurement on the other subsystem. This maximum similarity measure is a monotone function of the concurrence for pure states of two qubits; for mixed states it accounts for entanglement, dissonance, and classical correlations. Besides, we found a closed formula for evaluating the similarity degree of an arbitrary mix state of two two-dimensional systems.
Physical Review A, 2010
We have developed a general method for constructing a set of nonorthogonal bases with equal separ... more We have developed a general method for constructing a set of nonorthogonal bases with equal separations between all different basis states in prime dimensions. The results are that the corresponding biorthogonal counterparts are pairwise unbiased with the components of the original ...
International Conference on Quantum Information, 2007
Abstract We study the entanglement dynamics of two not interacting atoms coupled dispersively wit... more Abstract We study the entanglement dynamics of two not interacting atoms coupled dispersively with the same single mode. In the high energy limit there is no entanglement, the initial entanglement is as suddenly recovered as removed.
Physical Review A, 2007
... Luis Roa,1 R. Pozo-González,2,1 Marius Schaefer,1,3 and P. Utreras-SM1 1Center for Quantum Op... more ... Luis Roa,1 R. Pozo-González,2,1 Marius Schaefer,1,3 and P. Utreras-SM1 1Center for Quantum Optics and Quantum Information, Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile 2Departamento de Física, Tecnológico de Monterrey ...
Physical Review A, 2007
... Please use this identifier to cite or link to this item: http://hdl.handle.net/10533/29098\. T... more ... Please use this identifier to cite or link to this item: http://hdl.handle.net/10533/29098. Title: DRIVING A KNOWN STATE BY A DISCRETE SEQUENCE OF DIRECT MEASUREMENTS. Authors: LUIS ALBERTO ROA OPPLIGER. Keywords: AI-1030671. Issue Date: 2007. Publisher: ...
ChemInform, 2011
ABSTRACT Mixture of oxiranes (I), which are difficult to separate (no details given), allow a reg... more ABSTRACT Mixture of oxiranes (I), which are difficult to separate (no details given), allow a regiospecific synthesis of oxazepanones and morpholinones.
International Conference on Quantum Information, 2008
... 2 Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 B... more ... 2 Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte MG, Brazil. † carlos.saavedra@udec.cl Abstract: A probabilistic method for the unambiguous preparation of non-orthogonal polarization states is proposed. ...
Revista de biología marina y oceanografía, 2013
Physical Review A, 2006
We study the problem of driving an unknown initial mixed quantum state onto a known pure state wi... more We study the problem of driving an unknown initial mixed quantum state onto a known pure state without using unitary transformations. This can be achieved, in an efficient manner, with the help of sequential measurements on at least two unbiased bases. However here we found that, when the system is affected by a decoherence mechanism, only one observable is required in order to achieve the same goal. In this way the decoherence can assist the process. We show that, depending on the sort of decoherence, the process can converge faster or slower than the method implemented by means of two complementary observables. PACS numbers: 03.67.-a, 03.65.-w
Research in Optical Sciences, 2014
Arxiv preprint arXiv:0908.1686, 2009
Abstract: The task of changing the overlap between two quantum states can not be performed by mak... more Abstract: The task of changing the overlap between two quantum states can not be performed by making use of a unitary evolution only. However, by means of a unitary-reduction process it can be probabilistically modified. Here we study in detail the problem ...
Arxiv preprint quant-ph/ …, 2006
Abstract: We study the problem of driving a known initial quantum state onto a known pure state w... more Abstract: We study the problem of driving a known initial quantum state onto a known pure state without using a unitary evolution. This task can be achieved by means of von Neumann measurement processes, introducing N observables which are consecutively measured in ...
Tetrahedron: Asymmetry, 2004
A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-h... more A controlled reduction of (+)-(3R,5S)-5-methyl- and (+)-(3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium iodide 1 and 2 to generate (3R,5S)-5-methyl- and (3R,5S)-5-n-propyl-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridine 3 and 4, respectively, is reported. In addition, an enantioselective synthesis of (−)-(2R,6S)-dihydropinidine and (+)-(2S,6S)-indolizidine 167B starting from 3 and 4, respectively, was achieved.