Quantum Photonics & AI Group

Prof. Dirk Englund • Dr. Ryan Hamerly • Dr. Matthew Trusheim • Dr Avinash Kumar • Dr Charles Hsu • Dr Franco Wong


Silicon photonics for optical quantum technologies

Our goal is to generate complex quantum communication and computation (QCC) systems using silicon photonic integrated circuits; we are specifically interested in creating demo high-bit-rate quantum key distribution and scalable quantum information processing systems.

Waveguide-integrated SNSPD [1]

Waveguide-integrated SNSPD [1]

Advanced silicon photonic devices have been developed for classical information processing systems including optical interconnects in supercomputers [3]. Therefore, not only plain waveguides but optical modulators [4], buffers [5], and wavelength multiplexers [6] have been developed with low loss and processing rates exceeding 10 Gb/s [4]. 

Multiplexing circuit [2]

Multiplexing circuit [2]

Recently, researchers have begun to repurpose and omtimize these structures for QCC, including single photon sources [7], unitary gates [8] and single photon detectors. We motivated the development of PICs for QCC by designing quantum key distribution (QKD) protocols suitable for implementation not only in PICs but standard telecommunications networks. To that end, we proposed a protocol for QKD using dispersive optics [9] that can use standard telecommunication equipment aside from single photon detectors. The dispersive optical elements and the single-photon detectors can be realized on-chip using coupled ring waveguide resonators and superconducting nanowire single-photon detectors (SNSPD), respectively. We have developed waveguide-integrated SNSPDs together with the group of Professor Karl Berggren. These have been fabricated and shown to have very low jitter and small reset times [1].

Dispersive-optics QKD [9]

Dispersive-optics QKD [9]

Quantum photonic sources can be integrated on-chip as well. Four-wave mixing can be used to generate frequency-correlated photon pairs, and we proposed an integrated multiplexing circuit to increase the quality of photons emitted from spontaneous nonlinear optical sources [2].

Related Papers:

  1. F. Najafi*, J. Mower*, N.C. Harris, F. Bellei, A. Dane, C. Lee, P. Kharel, F. Marsili, S. Assefa, D. Englund, Karl K Berggren,  arXiv:1405.4244 (2014).
  2. J. Mower and D. Englund, Phys. Rev. A 84, 052326 (2011).

  3. W. Green, S. Assefa, A. Rylyakov, C. Schow, F. Horst, and Y. Vlasov (SEMICON, Chiba, Japan, 2010).

  4. W. M. Green, M. J. Rooks, L. Sekaric, and Y. A. Vlasov, Opt. Express 15, 17106 (2007).

  5. F. Xia, M. Rooks, L. Sekaric, and Y. Vlasov, Opt. Express 15, 11934 (2007).

  6. F. Horst, W. M. Green, S. Assefa, S. M. Shank, Y. A. Vlasov, and B. J. Offrein, Opt. Express 21, 11652 (2013)

  7. M. Davanco, J. R. Ong, A. B. Shehata, A. Tosi, I. Agha, S. Assefa, F. Xia, W. M. J. Green, S. Mookherjea, and K. Srinivasan, Applied Physics Letters 100, 261104 (2012).

  8. A. Crespi, R. Osellame, R. Ramponi, D. J. Brod, E. F. Galvao, N. Spagnolo, C. Vitelli, E. Maiorino, P. Mataloni, and F. Sciarrino, Nat Photon 7, 545 (2013).

  9. J. Mower, Z. Zhang, P. Desjardins, C. Lee, J. H. Shapiro, and D. Englund, Phys. Rev. A 87, 062322 (2013).