Research ArticleQUANTUM OPTICS

Deterministic reshaping of single-photon spectra using cross-phase modulation

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Science Advances  25 Mar 2016:
Vol. 2, no. 3, e1501223
DOI: 10.1126/sciadv.1501223
  • Fig. 1 Spectral reshaping of a single-photon wave packet using XPM.

    (A) Conceptual illustration of the scheme. The control pulse (displayed as an envelope) induces a dynamic nonlinear phase shift, that is, an instantaneous frequency modulation of the single-photon wave packet via XPM in the Kerr medium. (B) Measured group-delay spectrum of the photonic crystal fiber (PCF) used. The solid curve represents a sixth-order polynomial fitting. (C) Schematic of the experimental setup. The control pulse for XPM and the excitation pulse for photon pair generation are obtained from a pulsed laser source. PBS, polarizing beam splitter; DM, dichroic mirror; LPF, long-pass filter; (T)BPF, (wavelength-tunable) band-pass filter; PL, polarizer; PC, fiber polarization controller; NPBS, nonpolarizing 50/50 fiber beam splitter; SPCM, single-photon counting module; TDC, time-to-digital converter. H and V represent horizontal and vertical polarizations, respectively. The paths of signal and idler photons are swapped by the half-wave plate (HWP) in the experiment for entanglement detection (Fig. 4, D to F).

  • Fig. 2 Reshaping biphoton frequency correlations.

    (A to C) The time delay between the signal photons and the control pulses, ΔT, was set so that the signal photon spectrum was (A) unchanged (original JSA), (B) blue-shifted, and (C) broadened. The zero-detuning lines ωs = ωi are represented by the dot-dashed lines as a reference.

  • Fig. 3 Delay dependence of the marginal spectrum of heralded signal photons.

    (A) Experimental result. Coincidence counts were recorded as a function of the center wavelength of TBPF1, whereas that of TBPF2 was fixed at 1512 nm. (B) Sum of the coincidence counts for each time delay. The total coincidence count is unchanged regardless of the XPM interaction. (C) Numerical simulation result based on nonlinear-coupled Schrödinger equations (see section SI for details).

  • Fig. 4 Control over nonclassical interference between photons.

    (A to C) Engineering biphoton distinguishability in frequency. (A) Single count spectra of signal photons without (blue solid curve) and with (red solid curve) XPM and idler photons (blue dashed curve). (B) Two-photon interference fringes without (blue) and with (red) XPM reshaping. (C) Two-photon JSI without (left) and with (right) XPM. (D to F) Detection of two-photon frequency entanglement after the application of XPM. (D) Single count spectra of signal photons (blue dashed curve) and idler photons without (blue solid curve) and with (red solid curve) XPM. (E) Two-photon interference fringes without (blue) and with (red) XPM, each with different axes for comparison. The bump with XPM reshaping indicates that the entangled component in JSA acquired an antisymmetric wave function. (F) JSI without (left) and with (right) XPM. In (C) and (F), the zero-detuning lines are provided by the dot-dashed lines as a reference.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/3/e1501223/DC1

    I. Numerical simulation of XPM interaction between control and signal fields

    II. Estimating the upper bound of HOM interference visibility from experimental JSI

    III. Nonlinear polarization rotation

    IV. Two-photon interference fringes without XPM

    V. Prospects for larger frequency shifts

    Fig. S1. Numerically calculated JSA and JSI of the photon pairs.

    Fig. S2. Singular values and intensity spectra.

    Fig. S3. Testing nonlinear polarization rotation of the signal photon wave packets induced by the control pulses.

    Fig. S4. Two photon interference fringes without XPM.

    Fig. S5. Numerically simulated evolutions of the signal field in the PCF.

    References (5159)

  • Supplementary Materials

    This PDF file includes:

    • I. Numerical simulation of XPM interaction between control and signal fields
    • II. Estimating the upper bound of HOM interference visibility from experimental JSI
    • III. Nonlinear polarization rotation
    • IV. Two-photon interference fringes without XPM
    • V. Prospects for larger frequency shifts
    • Fig. S1. Numerically calculated JSA and JSI of the photon pairs.
    • Fig. S2. Singular values and intensity spectra.
    • Fig. S3. Testing nonlinear polarization rotation of the signal photon wave packets induced by the control pulses.
    • Fig. S4. Two photon interference fringes without XPM.
    • Fig. S5. Numerically simulated evolutions of the signal field in the PCF.
    • References (51–59)

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