Characterization and optimization of entangled states produced by
Characterization and optimization of entangled states produced by a selfphase-locked OPO J. Laurat, G. Keller, J. A. O. Huguenin T. Coudreau, N. Treps, C. Fabre Laboratoire Kastler Brossel, ENS, CNRS, UPMC
Quantum information with intense beams Quantum Information Measuring Entanglement OPOs “Non-separables” states Intense beams : quadratures of the electromagnetic field Optimizing entanglement Principes Conclusions Perspectives Frisno 8, february 2005 2
Qualifying inseparability Quantum Information Inseparability L. M. Duan et al. , C. Simon (PRL 2000) Measuring Entanglement OPOs Measuring entanglement Optimizing entanglement Entanglement $ Squeezing Conclusions Perspectives Frequency-degenerate operation required Frisno 8, february 2005 3
Covariance matrix formalism Quantum Information Single-mode covariance matrix Measuring Entanglement characterizes completely the state OPOs Covariance matrix and squeezing Optimizing entanglement Conclusions Perspectives Frisno 8, february 2005 4
Two-mode covariance matrix Quantum Information Two-mode covariance matrix Measuring Entanglement OPOs Measuring entanglement Optimizing entanglement Conclusions Perspectives Frisno 8, february 2005 5
Principle of OPOs Quantum Information Parametric down-conversion OPO Measuring Entanglement OPOs Principles Triply resonant optical cavity Optimizing entanglement Conclusions Perspectives Frisno 8, february 2005 6
Specificities of OPOs Quantum Information Oscillation threshold Measuring Entanglement OPOs Principles Emission of intense, coherent beams Orthogonally-polarized beams Optimizing entanglement (“type II” phase matching) Conclusions Perspectives Frisno 8, february 2005 7
Ensuring frequency-degenerate operation Quantum Information Measuring Entanglement Signal and idler frequency difference “arbitrary” Synchronizing/phase-locking two oscillators Add a linear coupling OPOs SPL OPO Optimizing entanglement Conclusions Perspectives Mason & Wong, Opt. Lett. (1998) Frequency & phase - locking of signal and idler Frisno 8, february 2005 8
Above threshold Quantum Information Simultaneous measurement of amplitude correlations and phase anti-correlations Measuring Entanglement OPOs Above threshold Optimizing entanglement Conclusions Perspectives Excess phase noise Frisno 8, february 2005 9
Below threshold – “Aligned” waveplate Quantum Information Measurement apparatus Measuring Entanglement OPOs Below threshold Optimizing entanglement Measurement results Conclusions Perspectives Frisno 8, february 2005 10
Below threshold – “aligned” waveplate Quantum Information Covariance matrix Measuring Entanglement OPOs Below threshold Optimizing entanglement Inseparability Conclusions Perspectives Frisno 8, february 2005 11
Below threshold – rotated waveplate Quantum Information Noise variances Measuring Entanglement OPOs Covariance matrix Below threshold Optimizing entanglement Conclusions Perspectives Inseparability Frisno 8, february 2005 12
Below threshold – maximizing entanglement Quantum Information Performing a non-local operation Measuring Entanglement OPOs Optimizing entanglement Covariance matrix local oscillator Inseparability Conclusions Perspectives Frisno 8, february 2005 13
Conclusions Quantum Information Measuring Entanglement OPOs Self-Phase Locked OPO a good tool to produce entangled states Self-Phase Locked OPO a good tool to show the general properties of entangled states Optimizing entanglement Polarization elements a good tool to manipulate Conclusions Perspectives entanglement Frisno 8, february 2005 14
Perspectives Quantum Information Working above threshold Measuring Entanglement OPOs Optimizing entanglement Full measurement of the covariance matrix Higher dimensions Conclusions Perspectives Frisno 8, february 2005 15
Frisno 8, february 2005 16
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