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Colonia Cuauhtemoc, Mexico

Dominguez-Serna F.A.,Research Center Cientifica Educacion Superior Of Ensenada | Mendieta-Jimenez F.J.,Mexicana University | Rojas F.,National Autonomous University of Mexico
Quantum Information Processing | Year: 2016

We study the degree of entanglement of arbitrary superpositions of m, n photon-added coherent states (PACS) (Formula presented.) using the concurrence and obtain the general conditions for maximal entanglement. We show that photon addition process can be identified as an entanglement enhancer operation for superpositions of coherent states (SCS). Specifically for the known bipartite positive SCS: (Formula presented.) whose entanglement tends to zero for (Formula presented.), can be maximal if al least one photon is added in a subsystem. A full family of maximally entangled PACS is also presented. We also analyzed the decoherence effects in the entangled PACS induced by a simple depolarizing channel . We find that robustness against depolarization is increased by adding photons to the coherent states of the superposition. We obtain the dependence of the critical depolarization (Formula presented.) for null entanglement as a function of (Formula presented.) and (Formula presented.). © 2016 Springer Science+Business Media New York Source

Leyva J.A.L.,Research Center Cientifica Educacion | Mondragon A.A.,Research Center Cientifica Educacion | Garcia E.,Autonomous University of Baja California | Mendieta F.J.,Mexicana University | And 2 more authors.
Optical Engineering | Year: 2012

We describe a homodyne optical Costas loop receiver intended to detect weak coherent states with diffused phase and suppressed carrier phase modulation. In order to get the information contained in the quadrature components of the optical field, we implement an 8-port receiver operating at 1550 nm, based on the manipulation of the state of polarization of both the local oscillator and the data signal. Employing binary phase-shift keying, we make measurements in the time and frequency domain of the quantum noise and bit error rate using an optimum loop filter, and compare the performance of our receiver against the standard quantum limit for the simultaneous quadrature detection, considering both ideal conditions and the overall efficiency of our set up. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Source

Garcia E.,Autonomous University of Baja California | Lopez J.A.,CICESE | Alvarez E.,Autonomous University of Baja California | Mendieta F.J.,Mexicana University | Arvizu A.,CICESE
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

In order to asses free space optical links, using a Cassegrain telescope, for both classical (i.e. coherent and direct detection) and quantum (coherent, Dolinar-Kennedy system) several scenarios were analyzed. This analysis was conducted through a software tool that uses some specific parameters imposed by the environmental condition and hardware used, such as: pointing and tracking errors, turbulence, modulations schemes, and visibility, among others; in order to obtain the general performance parameters of the simulated link, such as: bit error rate and the photons number. The software developed allows the user to produce useful way to assess the possible success of the implementation of the free space optical link, or a way to identify phenomena that might suggest hardware adjustments to improve the overall performance of the system. Results allow the revision of the expected link performance for a quantum key distribution system; although it is possible to use it for general optical quantum communications systems. © 2013 SPIE. Source

Garcia E.,Autonomous University of Baja California | Mendieta F.J.,Mexicana University | Lopez J.A.,CICESE | Alvarez E.,Autonomous University of Baja California | And 2 more authors.
Microwave and Optical Technology Letters | Year: 2013

We present an eight-port homodyne receiver implemented in free space technology for detection of weak coherent states that carry binary information. For transmitted power economy, we use suppressed-carrier modulation, therefore, we have implemented an optical Costas-loop-type carrier synchronizer. We obtain the quasiprobability Q function from the in-phase and quadrature observables that are simultaneously measured. Statistical results for the quadrature components are presented. We perform measurements for the bit error rate and the mutual information between transmitter-receiver. The results show that the proposed setup is suitable in quantum communications and continuous variable quantum key distribution systems. Copyright © 2013 Wiley Periodicals, Inc. Source

Lopez J.A.,CICESE | Garcia E.,UABC | Arvizu A.,CICESE | Mendieta F.J.,Mexicana University | And 2 more authors.
Microwave and Optical Technology Letters | Year: 2013

A free-space experimental set-up for measuring the quadrature components of weak-coherent-state laser signals, based on a homodyne Costas loop configuration is presented. Loop parameters are optimized as a trade-off between quantum and phase noises. Using binary phase-shift-keying modulation, measurements on the mutual information are presented for different photon numbers and phase errors. © 2012 Wiley Periodicals, Inc. Source

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