We present time-resolved emission experiments of semiconductor quantum dots in silicon 3D inverse-woodpile photonic band gap crystals. A systematic study is made of crystals with a range of pore radii to tune the band gap relative to the emission frequency. The decay rates averaged over all dipole orientations are inhibited by a factor of 10 in the photonic band gap and enhanced up to 2× outside the gap, in agreement with theory. We discuss the effects of spatial inhomogeneity, nonradiative decay, and transition dipole orientations on the observed inhibition in the band gap.

We have studied the reflectivity of CMOS-compatible three-dimensional silicon inverse woodpile photonic crystals at near-infrared frequencies. Polarization-resolved reflectivity spectra were obtained from two orthogonal crystal surfaces using an objective with a high numerical aperture. The spectra reveal broad peaks with maximum reflectivity of 67% that are independent of the spatial position on the crystals. The spectrally overlapping reflectivity peaks for all directions and polarizations form the signature of a broad photonic band gap with a relative bandwidth up to 16%. This signature is supported with stopgaps in plane wave bandstructure calculations and with the frequency region of the expected band gap. arXiv:1012.5263v2 [physics.optics]

Heralded single photons are prepared at a rate of ∼ 100 kHz via conditional measurements on polarizationnondegenerate biphotons produced in a periodically poled KTP crystal. The single-photon Fock state is characterized using high frequency pulsed optical homodyne tomography with a fidelity of (57.6 ± 0.1)%. The state preparation and detection rates allowed us to perform on-the-fly alignment of the apparatus based on real-time analysis of the quadrature measurement statistics. c 2009 Optical Society of America OCIS codes: 270.5585, 270.5570, 270.5290 The ability to produce single-photon states is of importance for optical quantum computation [1], quantum cryptography [2], and quantum state engineering [3]. Many of these applications require the photons to be generated with a high fidelity in a pure, well-defined spatiotemporal mode. This requirement can be approached by heralded single photons prepared via conditional measurements on biphotons produced due to spontaneous parametric down-conversion (SPDC) [4,5]. In this method, photon pairs produced in a nondegenerate optical parametric amplifier are split into two channels: trigger and signal. A single spatiotemporal mode is selected in the trigger channel and subjected to measurement with a single-photon counting module (SPCM). A detection event heralds preparation of the single photon in the conjugate spatiotemporal mode of the signal channel [6,7].A significant disadvantage of heralded photons is that they are not prepared on demand. The bimodal state of light produced due to each pump pulse (we specialize to the pulsed case) obeys thermal statistics:where the numbers refer to Fock states in the signal and trigger channels and γ is proportional to the pump field amplitude as well as the nonlinear susceptibility of the down-conversion medium. In the weak pump regime (γ ≪ 1), a trigger photon detection event indicates that the pulse in the signal channel contains a single photon. The probability of this event scales as ∝ γ 2 . If multiple photons need to be generated from n heralded sources simultaneously, the probability scales as ∝ γ 2n , which results in unpractically long data acquisition times. A higher pump intensity increases the biphoton production rate, but leads, with non-ideal photon detectors, to a spurious multiphoton component in the signal, and thus to reduced fidelities. A compromise between these two regimes is facilitated by higher pump pulse repetition frequencies. In this way, a reasonably high photon creation rate can be reached while maintaining a sufficiently low ratio between (n + 1)-and n-photon events. More frequent pump pulses however imply a reduced optical energy per pulse, which can be compensated by using novel materials with high nonlinear susceptibilities. Additionally, the quantum state measurement optoelectronics must be sufficiently fast to distinguish between neighboring laser pulses.In this Letter, we report homodyne tomography [8] of the single-photon Fock state |1 generated under such intermediate conditions. The prep...

The control of light scattering is essential in many quantum optical experiments. Wavefront shaping is a technique used for ultimate control over wave propagation through multiple-scattering media by adaptive manipulation of incident waves. We control the propagation of single-photon Fock states through opaque scattering media by spatial phase modulation of the incident wavefront. We enhance the probability that a single photon arrives in a target output mode with a factor 30. Our proof-of-principle experiment shows that the propagation of quantum light through multiple-scattering media can be controlled, with prospective applications in quantum communication and quantum cryptography.

We propose and experimentally verify a method to program the effective transmission matrix of general multiport linear optical circuits in random multiple-scattering materials by phase modulation of incident wavefronts. We demonstrate the power of our method by programming linear optical circuits in white paint layers with 2 inputs and 2 outputs, and 2 inputs and 3 outputs. Using interferometric techniques we verify our ability to program any desired phase relation between the outputs. The method works in a deterministic manner and can be directly applied to existing wavefront-shaping setups without the need of measuring a transmission matrix or to rely on sensitive interference measurements. electronic Kerr and free-carrier effects in an ultimate-fast optically switched semiconductor microcavity," J. Opt.