Measurement of the joint spectrum of entangled photons using rotary dispersion

Muhsin Hayat, Muhammad Yousaf

Abstract Subluminal and superluminal propagation of light, and normal and anomalous rotary photon drag are reported in this manuscript using control fields of the Milnor polynomial. A crater-type absorption spectrum is reported, having a central peak at the origin with a variation of positions. The normal and anomalous dispersion are associated with the low and high absorption regions. The group index varies in the range of − 1 × 10 7 ⩽ n g ⩽ 1 × 10 7 . This corresponds to a group velocity of v g = c / n g varying in the range of − 30 m s − 1 ⩽ v g ⩽ 30 m s − 1 . The maximum positive and negative delay times are measured to ± 0.002 s . It is reported that slow light propagation generates normal photon drag and fast light propagation generates anomalous rotary photon drag in a spinning medium. The rotary photon drag varies in the range of − 0.005 rad ⩽ θ d ⩽ 0.005 rad , where both normal and anomalous drag is also observed. The modified results will be useful in optical and biomedical sensors, and imaging and telecommunication technologies.

Amin Babazadeh, Rahman Nouroozi

Ryo Okamato, Shigeki Takeuchi

E. Y. Zhu, Costantino Corbari, Peter G. Kazansky +1 more

We experimentally demonstrate a simple method to measure the biphoton joint spectrum by mapping the spectral information onto the temporal domain using a dispersive medium. Various top-hat spectral filters are used to limit the spectral (and hence, temporal) extent of the broadband downconversion photons measured. The sharp edges of the spectral filters are utilized as spectral markers for dispersion characterization of the dispersive medium. This method allows dispersion characterization and joint spectral measurement to be completed simultaneously. The joint spectrum (which extends beyond 100 nm, centered about 1.5 micron) of the type-II downconverted photon pairs generated from a poled optical fiber is obtained with this method.

Adam Fallon, Daniel Hart, Evan J. Katz +3 more

NASA is developing quantum metrology capabilities for potential space-based quantum components in future navigation and communications systems. Innate knowledge of component operation is key for the space qualification of these components. This paper focuses on the measurement and analysis of an important characteristic of an entanglement source, the joint spectrum. We describe a spectrometer based on dispersive optical fibers and present experimental measurements of the joint spectrum of a highly non-degenerate SPDC-based entanglement source that emits entangled photons in the near-infrared and telecommunications bands. How the analysis of such a joint spectrum could be applied to the modeling and simulation of entanglement swapping operations as possible extensions of quantum networks is examined. Lastly, we discuss how the separability of the two-photon state is quantified via Schmidt decomposition and how the degree of separability impacts the spectral purity of heralded single-photon emissions.

Zeenat Baig, Zoya Shafique, Sean J. Bentley