Here are my reading notes on the quantum optics and photonics preprints in July 2018. This has been a good month for sources of nonclassical light: three groups implemented a source of polarisation-entangled photon pairs using Sagnac interferometer; Vernon et al proposed a CV-squeezed light source based on a χ^{(3)} microresonator; and three standards institutes INRIM (Italy), NPL (UK) and PTB (Germany) reported a concerted effort to standardise g^{(2)} measurements. On the detection side, Goswami, Heshami and Simon proposed a scheme for the non-destructive detection of single-photon time-bin qubits.
Vernon, Z., Quesada, N., Liscidini, M., Morrison, B., Menotti, M., Tan, K., & Sipe, J. E. arXiv:1807.00044. Scalable squeezed light source for continuous variable quantum sampling.
Squeezed light via effective χ^{(2)} interaction of χ^{(3)} microring resonator. This work proposes a squeezed light sources based on effective χ^{(2)} interaction of an integrated nanophotonic resonator with χ^{(3)} nonlinearity when it is driven by a strong continuous wave (CW) pump field. Realistic device parameters suggest a possibility of up to 10 dB squeezing for a 100pJ energy pulse. Nearby resonances can cause unwanted spontaneous four-wave mixing and Bragg-scattering four-wave mixing, so this work provides methods to detune these resonances to remove their effect.
Meyer-Scott, E., Prasannan, N., Eigner, C., Quiring, V., Donohue, J. M., Barkhofen, S., & Silberhorn, C. arXiv:1807.10092. High-performance source of indistinguishable entangled photon pairs based on hybrid integrated-bulk optics.
Polarisation-entangled photon pair generation using PDC in Sagnac loop. A PDC nonlinearity that is embedded in a Sagnac interferometer generates pairs of photons in the clockwise and in the anti-clockwise paths of the interferometer. Other than cycling direction, these pairs are mutually indistinguishable. While exiting the interferometer, the pairs interfere at a PBS and give an entangled singlet state with near-optimal performance in the relevant metrics of brightness, heralding efficiency and spectral purity. While the first two of these works use bulk PPKTP nonlinearity, the nonlinearity in the third work is a waveguide-based PPKTP.
Moreva, E., Traina, P., Kirkwood, R. A., López, M., Brida, G., Gramegna, M., Ruo-Berchera, I., Forneris, J., Tchernij, S. D., Olivero, P., Chunnilall, C. J., Kück, S., Genovese, M., & Degiovanni, I. P. arXiv:1807.04502. Feasibility study towards comparison of the g^(2)(0) measurement in the visible range.
Standardised procedure to estimate g^{(2)} and its uncertainty via Hanbury-Brown-Twiss (HBT) interference. This work is a joint effort from three measures and standards institutes, INRIM (Italy), NPL (UK) and PTB (Germany). g^{(2)} measurements are finicky as they are performing using HBT interference, which is susceptible to imperfections from background counts. The effect of these counts can be ameliorated by subtracting long-time-delay coincidences from both the true and the accidental coincidences (Fig. 1). The article also presents a thorough analysis of uncertainties including those from cross-correlations in coincidence counts.
Schneeloch, J., Knarr, S. H., Bogorin, D. F., Levangie, M. L., Tison, C. C., Frank, R., Howland, G. A., Fanto, M. L., & Alsing, P. M. arXiv:1807.10885. Introduction to the Absolute Brightness and Number Statistics in Spontaneous Parametric Down-Conversion.
Clear and simple tutorial on SPDC, introducing the basics of usual SPDC starting from Maxwell’s equations but going substantially beyond. Section V is a much-needed modern introduction to SPDC in waveguides and resonators. Section VI provides a quantum treatment of the situation in which the nonlinear process substantially depletes the pump.
Tang, H., Di Franco, C., Shi, Z., He, T., Feng, Z., Gao, J., Sun, K., Li, Z., Jiao, Z., Wang, T., Kim, M. S., & Jin, X. arXiv:1807.06625. Experimental Quantum Fast Hitting on Hexagonal Graphs.
Static waveguides for fun and profit. Glueing together the leaves of two tree graphs leads to graphs in which quantum walks traverse from one tree head to another faster than classical random walks. Hexagonal lattice the target to be hit quadratically faster via quantum walks as compared to classical random walks. Beautiful experimental setup with femtosecond-written waveguides.
Tschernig, K., Leon-Montiel, R. de J., Magana-Loaiza, O. S., Szameit, A., Busch, K., & Perez-Leija, A. arXiv:1807.07463. Multiphoton Discrete Fractional Fourier Dynamics in Waveguide Beam Splitters
Static waveguides for fun and profit (part-II). Theoretical proposal. Main message is that cleverly choosing the interaction between (e.g., femtosecond-written) waveguides can leads to interferometers that perform Fourier-like transformation.
Goswami, S., Heshami, K., & Simon, C. arXiv:1807.04732. Theory of cavity-enhanced non-destructive detection of photonic qubits in a solid-state atomic ensemble.
Non-destructive detection (NDD) of single-photon time-bin qubits via cavity enhancement. This work improves an earlier proposal and proof-of-principle demonstration of time-bin NDD to sensitivity levels that allow for single-photon detection. The sensitivity is improved by introducing a cavity and correcting for undesired probe-dependent phase shifts arising from the cavity.
Earlier reading lists: