This PDF file contains the front matter associated with SPIE Proceedings Volume 8272, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Fluorescent nanodiamonds (FNDs) have recently developed into an exciting new tool for bioimaging applications. The material possesses several unique features including high biocompatibility, easy bioconjugation, and perfect photostability, making it a promising optical nanoprobe in vitro as well as in vivo. This work explores the potential application of this novel nanomaterial as a photostable, nontoxic tracer in vivo using zebrafish as a model organism. We introduced FNDs into the yolk of a zebrafish embryo by microinjection at the 1-cell stage. Movements of the injected particles were investigated by using single particle tracking techniques. We observed unidirectional and stop-and-go traffic as part of the intricate cytoplasmic movements in the yolk cell. We determined a velocity in the range of 0.19 - 0.40 μm/s for 40 particles moving along with the axial streaming in the early developmental stage (1 to 2 hours post fertilization) of the zebrafish embryos.

Lanthanide doped nanocrystals with upconversion fluorescence emission have been synthesized. The surface of these nanocrystals are modified to render them water dispersible and biocompatible. Use of these nanocrystals for bioimaging introduces many advantages, for example, minimum photo-damage to biological samples, weak auto-fluorescence, high detection sensitivity, high light penetration depth, etc. Here, we use upconversion nanocrystals to label cancer cells and demonstrate confocal imaging of the labeled cells implanted in mouse muscle.

Further miniaturization of funcionalized quantum optical systems down to nm-dimensions and their integration into fibre optical networks is a major challange for future implementations of quantum information, quantum communication and quantum processing applications. Furthermore, scalability, long-term stability and room- as well as liquid helium temperature operation are benchmarking properties of such systems. In this paper, we present the realizations of fiber-coupled diamond-based single photon systems. First, an alignment free, μm-scale single photon source consisting of a single nitrogen vacancy center facet coupled to an optical fiber operating at room temperature is presented. Near-field coupling of the single nitrogen vacancy center is realized by placing a pre-selected nanodiamond directly on the fiber facet in a bottom-up approach. Its photon collection efficiency is comparable to a far-field collection via an air objective with a numerical aperture of 0.82. As the system can be simultaneously excited and its photons be recollected through the fiber, it can be used as a fiber-connected single quantum sensor that allows optical near-field probing on the quantum level. Secondly single nanodiamonds that contain nitrogen vacancy defect centers, are near-field coupled to a tapered fiber of 300 nanometer in diameter. This system provides a record-high number of 97 kcps single photons from a single defect center into a single mode optical fiber. The entire system can be cooled to liquid Helium temperatures and reheated without breaking. Furthermore, the system can be evanescently coupled to various nanophotonic structures, e.g. microresonators. The system can also be applied for integrated quantum transmission experiments and the realization of two-photon interference. It can be used as a quantum-randomnumber generator as well as a probe for nano-magnetometry.

Unique spectroscopic properties of isolated rare earth ions in solids offer optical linewidths rivaling those of trapped single atoms and enable a variety of recent applications. We design rare-earth-doped crystals, ceramics, and fibers with persistent or transient "spectral hole" recording properties for applications including high-bandwidth optical signal processing where light and our solids replace the high-bandwidth portion of the electronics; quantum cryptography and information science including the goal of storage and recall of single photons; and medical imaging technology for the 700-900 nm therapeutic window. Ease of optically manipulating rare-earth ions in solids enables capturing complex spectral information in 10⁵ to 10⁸ frequency bins. Combining spatial holography and spectral hole burning provides a capability for processing high-bandwidth RF and optical signals with sub-MHz spectral resolution and bandwidths of tens to hundreds of GHz for applications including range-Doppler radar and high bandwidth RF spectral analysis. Simply stated, one can think of these crystals as holographic recording media capable of distinguishing up to 10⁸ different colors. Ultra-narrow spectral holes also serve as a vibration-insensitive sub-kHz frequency reference for laser frequency stabilization to a part in 10¹³ over tens of milliseconds. The unusual properties and applications of spectral hole burning of rare earth ions in optical materials are reviewed. Experimental results on the promising Tm³⁺:LiNbO₃ material system are presented and discussed for medical imaging applications. Finally, a new application of these materials as dynamic optical filters for laser noise suppression is discussed along with experimental demonstrations and theoretical modeling of the process.

A brief overview of spectral properties and applications of organic materials for narrowband persistent spectral hole burning (SHB) and non-hole burning optical spectral filters is presented. The main focus is on the properties important for the filter applications in ultrasound-modulated optical tomography (UOT). Due to the large inhomogeneous broadening, the organic SHB filters may be used after the more narrowband primary SHB filters made of RE ion doped inorganic crystals to reduce red-shifted fluorescence from RE ions and improve the image quality. In addition non-hole burning organic materials, as secondary absorption optical filters to reduce phonon-mediated fluorescence from inorganic SHB crystals in UOT applications, are considered.

The partial transpose by which a subsystem's quantum state is solely transposed is of unique importance in quantum information processing from both fundamental and practical point of view. In this work, we present a practical scheme to realize a physical approximation to the partial transpose using local measurements on individual quantum systems and classical communication. We then report its linear optical realization and show that the scheme works with no dependence on local basis of given quantum states. A proof-of-principle demonstration of entanglement detection using the physical approximation of the partial transpose is also reported.

We explore basic necessary protocols to achieve fault tolerance for quantum computation in the cluster state and circuit models. For the cluster state model we simulate the implementation of an arbitrary rotation via only measurement on a decohered cluster state. Fidelity is used to quantify the accuracy of the initial cluster state and a gate fidelity for the arbitrary rotation is determined. In the circuit model we compare the accuracy of two methods that can be used to construct a logical zero state appropriate for the [7, 1, 3] Steane quantum error correction code in a non-equiprobable Pauli operator error environment: a fault tolerant method done by applying error correction on seven qubits all in the state zero, and a non-fault tolerant method done by implementing the encoding gate sequence. We find that the latter construction method, in spite of its lack of "fault tolerance," outputs a seven qubit state with a higher fidelity than the first (fault tolerant) method. However, the fidelity of the single qubit of stored information exhibits almost equivalent values between the two construction methods.

Mach-Zehnder interferometry based on mixing the coherent and the squeezed vacuum states of light has Heisenberg limited capabilities for phase estimation. This is also, because the quantum Cramer-Rao bound on sensitivity of phase estimation with the above interferometric scheme reaches the Heisenberg limit when the inputs are mixed in hear equal proportions. We show that a detection strategy based on the measurement of parity of photon number in one of the output modes of the interferometer saturates the quantum Cramer-Rao bound of the interferometric scheme, and therefore- as a consequence- hits the Heisenberg limit when the inputs are mixed in equal intensities.

We show that electromagnetically induced transparency can be used to store coherently and to retrieve light pulses propagating in a one-dimensional waveguide through a line of atoms, thereby realizing light-controlled on-demand quantum memory. Storage can be highly efficient even with just a few atoms despite inter-atomic scattering interference due to the one-dimensional constraint.

We report the substrate effects on the zero-phonon transitions and suppression of phonon side bands in the NV center spectrum. Fluorescence spectra of NV centers in cryogenic temperatures were measured by depositing diamond nanocrystals on different substrates including glass slides, undoped Si, and silica (1~2μm) on undoped Si (SiO₂/Si). We found that SiO₂/Si substrate was an effective substrate to suppress the phonon side band from spectra of NV^- centers. Temperature dependence of NV^- zero-phonon line Debye-Waller factor on Si and SiO₂/Si were measured, from 2.5K to 230K, Debye-Waller factor decreased linearly on both of the two substrates.

We demonstrate coupling between the zero phonon line (ZPL) of nitrogen-vacancy centers in diamond and the modes of optical micro-resonators fabricated in single crystal diamond membranes sitting on a silicon dioxide substrate. A more than ten-fold enhancement of the ZPL is estimated by measuring the modification of the spontaneous emission lifetime. The cavity-coupled ZPL emission was further coupled into on-chip waveguides thus demonstrating the potential to build optical quantum networks in this diamond on insulator platform.

We demonstrate optical single electron spin-initialization, -storage and -readout in a single self-assembled InGaAs quantum dot using a spin memory device. Single electron spin relaxation is monitored over timescales exceeding ≥30μs, defined only by extrinsic experimental parameters such as the optical detection efficiency. The selective generation of a single electron in the dot is performed by resonant optical excitation and subsequent partial exciton ionization; the hole is removed from the dot whilst the electron remains stored. When subject to a magnetic field applied in Faraday geometry, we show how the spin of the electron can be prepared with a well defined spin projection relative to the light propagation direction simply by controlling the voltage applied to the gate electrode. The spin is stored then in the dot before being read out using an optical implementation of spin to charge conversion, whereby the spin projection of the electron is mapped onto a more robust variable, the charge state of the dot. After spin to charge conversion, we show how the charge occupancy can be repeatedly and non-perturbatively measured by pumping a luminescence recycling transition. The approach is shown to provide a readout signal 10⁴ times stronger per spin when compared to previous methods. In combination with spin manipulation using the optical Stark effect or microwaves, our approach provides an ideal basis for probing spin coherence in single self-assembled quantum dots over long timescales and the development of methods for coherent spin control.

We describe quantum information schemes involving photon polarization and the spin of a single electron trapped in a self-assembled quantum dot. Such schemes are based on spin-selective reflection in the weak-coupling regime of cavity quantum electrodynamics. We discuss their practical implementation in oxide-apertured micropillar cavities. We introduce a technique, based on the creation of small surface defects by means of a focused intense laser beam, to permanently tune the optical properties of the microcavity without damaging the cavity quality. This technique allows low-temperature polarization-selective tuning of the frequencies of the cavity modes and the quantum dot optical transitions.

Here we demonstrate the ion-implantation of fluorine as an alternative doping method for ZnMgSe/ZnSe QWs. The photoluminescence measurements of F-implanted ZnSe QWs show the correlation between the number of sharp recombination peaks of F-donor bound-excitons and the implantation dose as well as the saturation of the luminescence intensity related to a donor. When special techniques such as selective implantation through a mask and registration of single ion impacts are applied on micro-, nano-cavities, the ion implantation can be an attractive alternative fluorine doping method for quantum information technology based on fluorine impurities in ZnSe.

Absorption of light is a fundamental process in imaging. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the quantum limits of absorption imaging. Here we report the first absorption imaging of a single isolated atom, the smallest and simplest system reported to date. Contrasts of up to 3.1(3)% were observed in images of a laser cooled ¹⁷⁴Yb⁺ ion confined in vacuum by a radio-frequency Paul trap. This work establishes a new sensitivity bound for absorption imaging with a 7800x improvement over the contrast previously observed in imaging a single molecule.

Quantum memory is considered to be one of the key elements in the fields of quantum computing and quantum communication. Warm atomic vapor cells for quantum memory in DLCZ (for Duan, Lukin, Cirac, and Zoller) protocol are appealing due to the perceived reduction in experimental complexity and commercial availability. However, reported results on quantum memory using warm vapor cells were done under widely different experimental conditions and produced ambiguous results. In order for the memory to exhibit non-classical behavior, to a high degree of certainty, the cross-correlation value between the Stokes and anti-Stokes photons needs to be greater than two. In this work we demonstrate quantum memory with cross-correlation value between the Stokes and anti-Stokes photons greater than two lasting for 4 μs using warm Rb vapor with buffer gas for nearly co-propagating write and read beams.

Qubits based on trapped ions are being investigated as a promising platform for scalable quantum information processing. One challenge associated with the scalability of such a multi-qubit trapped ion system is the need for an ultraviolet (UV) laser beam switching and control system to independently modulate and address large qubit arrays. In this work, we propose and experimentally demonstrate a novel architecture for a laser beam control system for trapped ion quantum computing based on fast electro-optic amplitude switching and high-fidelity electromechanical beam shuttering using a microelectromechanical systems (MEMS) deflector coupled into a single-mode optical fiber. We achieve a rise/fall time of 5 ns, power extinction of -31 dB, and pulse width repeatability of > 99.95% using an electrooptic switch based on a β-BaB₂O₄ (BBO) Pockels cell. A tilting MEMS mirror fabricated using a commercial foundry was used to steer UV light into a single-mode optical fiber, resulting in an electromechanical beam shutter that demonstrated a power extinction of -52 dB and a switching time of 2 μs. The combination of these two technologies allows for high-fidelity power extinction using a platform that does not suffer from temperature-induced beam steering due to changes in modulation duty cycle. The overall system is capable of UV laser beam switching to create the resolved sideband Raman cooling pulses, algorithm pulses, and read-out pulses required for quantum computing applications.