Shaping the spectrum of entangled photons M Hendrych

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Shaping the spectrum of entangled photons M. Hendrych, A. Valencia, M. Mičuda, Xiaojuan Shi,

Shaping the spectrum of entangled photons M. Hendrych, A. Valencia, M. Mičuda, Xiaojuan Shi, Payam Abolghasem, Amr Helmy, and J. P. Torres ICFO – Institute of Photonic Sciences Barcelona

Quantum Optical Applications • Quantum computing – Quantum computer (calculations, database lookup, etc. )

Quantum Optical Applications • Quantum computing – Quantum computer (calculations, database lookup, etc. ) – Material design, simulations • Quantum cryptography • Quantum random-number generation • Quantum metrology – Clock synchronization – Quantum optical coherence tomography – Squeezed states (grav. waves, magnetometers) • Quantum lithography (NOON states) • Quantum lawn-mowers

Outline • What we do – Frequency correlations of entangled photon pairs – Bandwidth

Outline • What we do – Frequency correlations of entangled photon pairs – Bandwidth control – Waveform shaping • How we do it – Tailoring group velocities by pulse-front tilt (angular dispersion) – Tailoring momentum-frequency entanglement using noncollinear geometries (spatial-to-spectral mapping) • Uof. T/ICFO collaboration – Design waveguides with suitable dispersive properties

 • Anticorrelated • Correlated Types of correlations • Uncorrelated

• Anticorrelated • Correlated Types of correlations • Uncorrelated

Applications • Anticorrelated – Clock synchronization (A. Valencia et al. , Appl. Phys. Lett

Applications • Anticorrelated – Clock synchronization (A. Valencia et al. , Appl. Phys. Lett 85 , 2655 (2004)) – Dispersion compensation (even orders) (J. D. Franson, Phys. Rev. A 45, 3126 (1992)) • Correlated – Clock synchronization and position measurement (V. Giovannetti et al. , Nature 412, 417 (2001)) – Dispersion compensation (all orders) • Uncorrelated – Heralded single photons (pure state)

Bandwidth control

Bandwidth control

Bandwidth control • Generation of ultrashort biphotons M. Hendrych et al. , ar. Xive

Bandwidth control • Generation of ultrashort biphotons M. Hendrych et al. , ar. Xive quant-ph/0807. 4063 • Broad bandwidth in OCT S. Carrasco et al. , Opt. Lett. 29, 2429 (2004) – increases axial resolution of imaging • Quantum illumination S. Lloyd, Science 321, 1463 (2008) – Increases efficiency of detecting an object by 2 m, m is Nasr number bits. Rev. of Lett. entanglement et al. , of Phys. 100, 183601 (2008)

Waveform shaping

Waveform shaping

Spontaneous parametric downconversion State of SPDC photons Nonlinear crystal Joint spectrum Phase mismatch

Spontaneous parametric downconversion State of SPDC photons Nonlinear crystal Joint spectrum Phase mismatch

How to tailor the biphoton’s spectrum? By controlling – group velocities – group velocity

How to tailor the biphoton’s spectrum? By controlling – group velocities – group velocity dispersion – spatial shape of the pump beam • Search for material and wavelengths with suitable properties (Oxford, MIT) ? ? ? MIT desing, ne search. * • Design materials using quasi phase-matching and chirped * (Boston, Stanford, Barcelona) • Phase matching using Bragg-reflection waveguides (Toronto) • Pulse-front tilt (Barcelona) • Noncollinear geometries (Barcelona)

Pulse-front tilt y Effective group velocity dispersion

Pulse-front tilt y Effective group velocity dispersion

Experimental setup SHG - second harmonic generation, M - mirrors, G - gratings, PBS

Experimental setup SHG - second harmonic generation, M - mirrors, G - gratings, PBS - polarizing beamsplitter, Mono - monochromators, D - detectors, & - counter and coincidence electronics.

Joint spectrum BBO: type II, 2 mm Theory Experiment

Joint spectrum BBO: type II, 2 mm Theory Experiment

Joint spectrum – anticorrelated Theory Experiment

Joint spectrum – anticorrelated Theory Experiment

Joint spectrum – uncorrelated Theory Experiment

Joint spectrum – uncorrelated Theory Experiment

Joint spectrum – correlated Theory Experiment

Joint spectrum – correlated Theory Experiment

Frequency correlations in HOM M. Hendrych et al. , Opt. Lett. 32, 2339 (2007)

Frequency correlations in HOM M. Hendrych et al. , Opt. Lett. 32, 2339 (2007)

Bandwidth control Singles Coincidences M. Hendrych et al. , ar. Xive quant-ph/0807. 4063 PRA

Bandwidth control Singles Coincidences M. Hendrych et al. , ar. Xive quant-ph/0807. 4063 PRA *

Bandwidth Control with Chirped Quasi-Phase Matching Collaboration with Boston & Stanford Univs. NORMALIZED INTENSITY

Bandwidth Control with Chirped Quasi-Phase Matching Collaboration with Boston & Stanford Univs. NORMALIZED INTENSITY S. Carrasco et al. , Opt. Lett. 29, 2429 (2004) M. Nasr et al. , Phys. Rev. Lett. 100, 183601 (2008)

Spatial-to-spectral mapping S. Carrasco et al. , PRA 70, 043817 (2004)

Spatial-to-spectral mapping S. Carrasco et al. , PRA 70, 043817 (2004)

Spatial-to-spectral mapping Space Joint spectrum Citace teorie Silvia? *

Spatial-to-spectral mapping Space Joint spectrum Citace teorie Silvia? *

Spatial-to-spectral mapping Joint spectrum along the antidiagonal Idler wavelength Image of spatial mode of

Spatial-to-spectral mapping Joint spectrum along the antidiagonal Idler wavelength Image of spatial mode of the pump A. Valencia et al. , Phys. Rev. Lett. 99, 243601 (2007) Signal wavelength

Modifying the frequency correlations via spatial-to-spectral mapping

Modifying the frequency correlations via spatial-to-spectral mapping

Combining pulse-front tilt and spatial-to-spectral mapping X. Shi et al. , Opt. Lett. 33,

Combining pulse-front tilt and spatial-to-spectral mapping X. Shi et al. , Opt. Lett. 33, 875 (2008)

Collaboration with Uof. T Amr Helmy Payam Abolghasem Goal: Design Bragg-reflection waveguides to produce

Collaboration with Uof. T Amr Helmy Payam Abolghasem Goal: Design Bragg-reflection waveguides to produce 1) entangled photons with desired bandwidth 2) frequency-uncorrelated biphotons

Bragg-reflection waveguides (BRW) - Al. Ga. As structure - Design of the structure allows

Bragg-reflection waveguides (BRW) - Al. Ga. As structure - Design of the structure allows controlling dispersive properties

Compound semiconductors Alx. Ga 1 -x. As – mature fabrication technology – large transparency

Compound semiconductors Alx. Ga 1 -x. As – mature fabrication technology – large transparency window – large nonlinear coefficient – large damage threshold – monolithic integration • cost effectiveness • small device size • portable devices • low power consumption • reliable performance

Phase-matching and GVD control with BR waveguides

Phase-matching and GVD control with BR waveguides

Joint spectrum w/ BR waveguides Type I for different ridge widths W

Joint spectrum w/ BR waveguides Type I for different ridge widths W

Joint spectrum w/ BR waveguides Type II Dl = 670 nm Dl = 20

Joint spectrum w/ BR waveguides Type II Dl = 670 nm Dl = 20 nm Dl = 134 nm W = 725 nm lp = 752 nm L = 1 mm W = 2500 nm lp = 775 nm L = 1 mm

Summary • Frequency correlations: Thank you!!! • Bandwidth: • Waveform: • Fabricate waveguides and

Summary • Frequency correlations: Thank you!!! • Bandwidth: • Waveform: • Fabricate waveguides and measure their properties