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Demonstration ofTwo-Plasmon

Quantum Interference

Hyunseok Lee

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■ Overview

• Background Recap• Surface Plasmon • Two Photon Quantum Interference

• Experiment Procedure• Schematic• Theoretical analysis• Waveguide Design

• Result & Conclusion• Measurement• Conclusion• Future research

Plasmonic TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

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■ Surface Plasmon

• Electronic-optical excitations

• Strongly interact with environment• Decoherence question unsettled

• Test of indistinguishability!

Plasmonic TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

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Plasmonic TPQI

■ Two Photon Quantum Interference

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

Represent the electric fields of the modes by annihilation operators:

Represent the action of the beam splitter by an operator with two assumptions:

Then the final state of the system given one photon in each input follows:

Detectors placed at the outputs will never click simultaneously!

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■ Schematic (1)

• Laser -> SPDC -> single photon pairs• Waveguide -> converted to plasmon -> TPQI • Back to photon -> detectors

Plasmonic TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

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■ Schematic (2) Plasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

* C. Hong, Z. Ou, L. Mandel, Phys. Rev. Lett. 59, 2044-2046 (1987).

• Dielectric case

• Challenge: Plasmonic waveguide• Theory• Simulation• Fabrication

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■ TPQI in a Lossy Coupler (1)Plasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Supermodes

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■ TPQI in a Lossy Coupler (2)Plasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

𝑃 (1a ,1b )=|𝑡|4+|𝑟|4+ [𝑡 2𝑟 ∗2+𝑟 2𝑡∗ 2 ¿ 𝐼 ,

𝐻𝑂𝑀𝑣𝑖𝑠𝑖𝑏𝑖𝑙𝑖𝑡𝑦=1−𝑃 (1a ,1b ; 𝐼=1 )𝑃 (1a ,1b ; 𝐼=0 )

=1−2cos2∆𝜃 .

*S. Barnett, J. Jeffers, A. Gatti, R. Loudon,Phys. Rev. A. 57, 2134(1998)

Coin

cide

nce

Rate

Delay

Ideal TPQI with loss

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■ SimulationPlasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

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■ Waveguide Design (1)Plasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• DLSPPW design• Optimized dimension & material

* R. Briggs, J. Grandidier, S. Burgos, E. Feigenbaum, H. A. Atwa-ter, Nano Lett. 2010, 10(12)

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■ Waveguide Design (2)Plasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Dielectric waveguide for comparison• S-bends prevent stray light background

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94.4+/-0.3%

0.12+/-0.01 ps

■ MeasurementPlasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Plasmonic TPQI is clearly shown

93.2+/-1.0%

0.11+/-0.01 ps

Plasmonic TPQIPhotonic TPQI

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■ ConclusionPlasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Successfully demonstrated unam-biguous quantum interference in plasmonic waveguides• Close correspondence between di-

electric and plasmonic• Identical photons remain indistinguish-

able

• High degree of coherence• Application in quantum computing if

loss can be mitigated.

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■ Future ResearchPlasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Further study of plasmon• Dispersive regime

• Extending the technology• Integrated quantum photonics

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■ AcknowledgementsPlasmonic

TPQI

Recap

Surface Plasmon

TPQI

Procedure

Schematic

Theory

WaveguideDesign

Result

Conclusion

Future re-search

• Air Force Office of Scientific Research• Kavli Nanoscience Institute

• Further reading:J. S. Fakonas, H. Lee, Y. A. Kelaita, H. A. Atwater, Nat. Photonics 8, 317–320 (2014).

Thank you for listening!