title: Noncollinear parametric fluorescence by chirped quasi-phase matching for monocycle temporal entanglement.
abstract: Quantum entanglement of two photons created by spontaneous parametric downconversion (SPDC) can be used to probe quantum optical phenomena during a single cycle of light. Harris [Opt. Express 98, 063602 (2007)] suggested using ultrabroad parametric fluorescenc generated from a quasi-phase-matched (QPM) device whose poling period is chirped. In the Harris's original proposal, it is assumed that the photons are collinearly generated and then spatially separated by frequency filtering Here, we alternatively propose using noncollinearly generated SPDC. In our numerical calculation, to achieve 1.2 cycle temporal correlation for a 532 nm pump laser, only 10% -chirped device is sufficien when noncollinear condition is applied, while a largely chirped (50%) device is required in collinear condition. We also experimentally demonstrate an octave-spanning (790-1610 nm) noncollinear parametric fluorescenc from a 10% chirped MgSLT crystal using both a superconducting nanowire single-photon detector and photomultiplier tube as photon detectors. The observed SPDC bandwidth is 194 THz, which is the largest width achieved to date for a chirped QPM device. From this experimental result, our numerical analysis predicts that the bi-photon can be compressed to 1.2 cycles with appropriate phase compensation.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.forename: Ryo
authors.initials: R
authors.lastname: Okamoto
authors.forename: Hwan Hong
authors.initials: HH
authors.lastname: Lim
authors.forename: Shanthi
authors.initials: S
authors.lastname: Subashchandran
authors.forename: Masayuki
authors.initials: M
authors.lastname: Okano
authors.forename: Labao
authors.initials: L
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Kang
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Peiheng
authors.initials: P
authors.lastname: Wu
authors.forename: Toru
authors.initials: T
authors.lastname: Hirohata
authors.forename: Sunao
authors.initials: S
authors.lastname: Kurimura
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeuchi