Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session J7: Single Photons |
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Chair: Elizabeth Goldschmidt, Joint Quantum Institute Room: Delaware CD |
Wednesday, June 10, 2015 2:00PM - 2:12PM |
J7.00001: Studying the lower limit of human vision with a single-photon source Rebecca Holmes, Bradley Christensen, Whitney Street, Ranxiao Wang, Paul Kwiat Humans can detect a visual stimulus of just a few photons. Exactly how few is not known---psychological and physiological research have suggested that the detection threshold may be as low as one photon, but the question has never been directly tested. Using a source of heralded single photons based on spontaneous parametric downconversion, we can directly characterize the lower limit of vision. This system can also be used to study temporal and spatial integration in the visual system, and to study visual attention with EEG. We may eventually even be able to investigate how human observers perceive quantum effects such as superposition and entanglement. Our progress and some preliminary results will be discussed. [Preview Abstract] |
Wednesday, June 10, 2015 2:12PM - 2:24PM |
J7.00002: How a Single Photon Can Act as Many Photons Josiah Sinclair, Greg Dmochowski, Matin Hallaji, Amir Feizpour, Aephraim Steinberg We experimentally show how a single, post-selected photon may induce a non-linear cross-phase shift that is five times larger than the nominal single photon effect. Using a weak cross-Kerr interaction, we deterministically couple two coherent state optical fields and exploit weak-value amplification (WVA) to increase the effect that one field (the ``signal'') has on the other (the ``probe''). Due to the (weak) entangling interaction, appropriate preparation and post-selection of the signal field leads to interference of different possible probe states and an anomalously large cross-phase shift. This amplification only occurs for particular pre- and post-selections of the signal field; larger amplification arises when the final state is nearly orthogonal to the initially prepared state and, therefore, occurs less frequently. A laser-cooled cloud of $^{85}$Rb atoms is used to mediate the cross-Kerr interaction; the signal field imprints a phase shift on the probe laser, which grows linearly with the photon number in the signal pulse. That is, the probe effectively measures the photon number in the signal beam. The signal field is prepared in a given superposition of two polarizations, one of which interacts with the probe field more strongly than the other. After the interaction, detection of an individual signal photon (using a single photon detector) which is nearly orthogonally polarized causes the probe to acquire an additional single-photon phase shift that is amplified by the degree of orthogonality. We demonstrate an amplification factor of five. [Preview Abstract] |
Wednesday, June 10, 2015 2:24PM - 2:36PM |
J7.00003: Continuous Nondestructive Detection of Individual Photons Kristin Beck, Mahdi Hosseini, Yiheng Duan, Wenlan Chen, Vladan Vuleti\'{c} The nondestructive detection of optical photons is an enabling technology with applications in quantum information, simulation and communication. We present a detection scheme that continuously detects photons without destroying them. Photons to be measured (signal photons) are sent through an ensemble of $^{133}$Cs atoms, where they travel as slow-light polaritons that are, in turn, coupled to a high finesse optical cavity. The atomic component of the polariton rotates the polarization of light that is transmitted through the cavity, which we detect. We show that the system is capable of non-destructively detecting individual signal photons by measuring a second-order correlation function between the signal and detection paths of $g_2(0) > 5$. [Preview Abstract] |
Wednesday, June 10, 2015 2:36PM - 2:48PM |
J7.00004: Towards a deterministic single-photon source by Rydberg FWM effect in a thermal microcell Yi-Hsin Chen, Fabian Ripka, Robert L\"ow, Tilman Pfau The generation and manipulation of single photons are the key ingredients for the photonic-based quantum security communication and information processing. One promising candidate to realize the on-demand single-photon source is based on the combination of four-wave-mixing (FWM) and Rydberg blockade effects in a micrometer scale thermal microcell [1]. Similar to our past studies of coherent Rydberg dynamics [2] and van-der Waals interaction [3] in a three-level system, we implement a pulsed FWM scheme to observe both coherent dynamics and effects of dephasing due to Rydberg-Rydberg interaction [4]. Furthermore, we investigate the effects of the excitation volume by use of low- and high- NA optics and spatial confinement. We discuss prospects for the generation of non-classical~light. \\[4pt] [1] M. M. M\"{u}ller et al., PRA 87, 053412 (2013)\\[0pt] [2] Huber et al., PRL 107, 243001 (2011)\\[0pt] [3] Baluktsian et al., PRL 110, 123001 (2013)\\[0pt] [4] Huber et al., PRA 90, 053806 (2014) [Preview Abstract] |
Wednesday, June 10, 2015 2:48PM - 3:00PM |
J7.00005: Hong-Ou-Mandel Interference Between Triggered And Heralded Single Photons From Separate Atomic Systems Alessandro Cere, Victor Leong, Gurpreet Kaur Gulati, Bharath Srivathsan, Sandoko Kosen, Christian Kurtsiefer The realization of quantum networks and long distance quantum communication rely on the capability of generating entanglement between separated nodes. We demonstrate the compatibility of two different sources of single photons: a single atom and four-wave mixing in a cold cloud of atoms. The four-wave mixing process in a cloud of cold $^{87}$Rb generates photon pairs. The cascade level scheme used ensures the generation of heralded single photons with exponentially decaying temporal envelope. The temporal shape of the heralding photons matches the shape of photons emitted by spontaneous decay but for the shorter coherence time A single $^{87}$Rb atom is trapped in an far-off-resonance optical dipole trap and can be excited with high probability using a short ($\approx$3\,ns) intense pulse of resonant light, emitting a single photon by spontaneous decay. A large numerical aperture lens collects $\approx$4\% of the total fluorescence. The heralded and the triggered photons are launched into a Houng-Ou-Mandel interferometer: a symmetrical beam-splitter with outputs connected to single photon detectors. Scanning the relative delay between the two sources we observe the HOM dip with a maximum visibility of 70$\pm$4\%. [Preview Abstract] |
Wednesday, June 10, 2015 3:00PM - 3:12PM |
J7.00006: Loading a single photon into an optical cavity Shengwang Du, Chang Liu, Yuan Sun, Luwei Zhao, Shanchao Zhang, M.M.T. Loy Confining and manipulating single photons inside a reflective optical cavity is an essential task of cavity quantum electrodynamics (CQED) for probing the quantum nature of light quanta. Such systems are also elementary building blocks for many protocols of quantum network, where remote cavity quantum nodes are coupled through flying photons. The connectivity and scalability of such a quantum network strongly depends on the efficiency of loading a single photon into cavity. In this work we demonstrate that a single photon with an optimal temporal waveform can be efficiently loaded into a cavity. Using heralded narrow-band single photons with exponential growth wave packet whose time constant matches the photon lifetime in the cavity, we demonstrate a loading efficiency of more than 87 percent from free space to a single-sided Fabry-Perot cavity. Our result and approach may enable promising applications in realizing large-scale CQED-based quantum networks. [Preview Abstract] |
Wednesday, June 10, 2015 3:12PM - 3:24PM |
J7.00007: Two-photon interference with atom-resonanant photon pairs Federica A. Beduini, Joanna A. Zielinska, Vito Giovanni Lucivero, Morgan W. Mitchell We demonstrate atomic filtering of frequency-degenerate photon pairs from a sub-threshold optical parametric oscillator (OPO). The filter, a modified Faraday anomalous dispersion optical filter (FADOF), achieves 70\% peak transmission simultaneous with 57 dB out-of-band rejection and a 445 MHz transmission bandwidth. When applied to the OPO output, only the degenerate mode, containing one-mode squeezed vacuum, falls in the filter pass-band; all other modes are strongly suppressed. The high transmission preserves non-classical continuous-variable features, e.g. squeezing or non-gaussianity, while the high spectral purity allows reliable discrete-variable detection and heralding. Correlation and atomic absorption measurements indicate a spectral purity of 96\% for the individual photons, and 98\% for the photon pairs. Interference between an unknown two-photon state (a ``biphoton'') and the two-photon component of a reference state gives a phase-sensitive arrival-time distribution containing full information about the biphoton temporal wave function. Using a coherent state as a reference, we observe this interference and reconstruct the wave function of single-mode biphotons from a low-intensity narrow band squeezed vacuum state. \\[4pt] Reference: Phys. Rev. Lett. 113, 183602 (2014) [Preview Abstract] |
Wednesday, June 10, 2015 3:24PM - 3:36PM |
J7.00008: Development and Characterization of a Periodically Poled Lithium Niobate Photon Pair Source Sean Krupa, Eric Stinaff, Lee Oesterling, David Nippa A photon pair source made of Periodically Poled Lithium Niobate (PPLN) was developed for degenerate and non-degenerate type-0 Spontaneous Parametric Downconversion (SPDC) of 775-780nm light to telecom wavelengths. Research consisting of characterization and an iterative design/development process resulted in a PPLN photon pair source suitable for commercial application. Focusing on losses and heralding efficiency, different waveguide geometries and manufacturing techniques were tested, characterized, and optimized. The best PPLN devices created feature insertion losses of 3dB and heralding efficiencies of 70{\%} making them exceptional for use in emerging quantum applications. Further integration of fiber optic components will be done to expand the capabilities of the devices. Other current research is focused on further characterization of the devices, specifically the SPDC spectra and a direct measurement of the effective nonlinear coefficient in the PPLN waveguides. These measurements will be discussed in detail as well an overview of the project. This work seeks to improve the performance of PPLN waveguides for use in quantum technologies. [Preview Abstract] |
Wednesday, June 10, 2015 3:36PM - 3:48PM |
J7.00009: Temporal Multiplexing toward Deterministic Single Photon Generation Fumihiro Kaneda, Bradley Christensen, Jia Jun Wong, Hee-Su Park, Kevin McCusker, Paul Kwiat Heralded single photon sources via spontaneous parametric down-conversion have been a key technology for demonstrating small-scale quantum information processing, yet their low generation efficiency is also a key limitation for further scaling up quantum optical information technology. Multiplexed heralded single-photon sources [1-3] have been proposed for pseudo-deterministic generation of single photons without enhancing unwanted multi-photon generation. We report on our recent efforts toward a periodic and deterministic single-photon source by the use of an adjustable optical delay line and a high-efficiency heralded single-photon source. Multiplexing for up to 30 cycles of the periodically pumped heralded single-photon source, we observed a single-photon probability of 39 $\pm$ 1\% in periodic output time windows, corresponding to more than six times enhancement over a non-multiplexed case, while the ratio of single- and multi-photon probabilities is as low as the non-multiplexed case. We anticipate that the time-multiplexing technique will enable larger scale quantum information processing system than ever realized. [1] A. L. Migdall, et al., PRA 66, 053805 (2002). [2] T. Pittman, et al., PRA 66, 042303 (2002). [3] K. McCusker and P. G. Kwiat, PRL 103, 163602 (2009). [Preview Abstract] |
Wednesday, June 10, 2015 3:48PM - 4:00PM |
J7.00010: Optimizing Photon Collection from Point Sources with Adaptive Optics Alexander Hill, David Hervas, Joseph Nash, Martin Graham, Alexander Burgers, Uttam Paudel, Duncan Steel, Paul Kwiat Collection of light from point-like sources is typically poor due to the optical aberrations present with very high numerical-aperture optics. In the case of quantum dots, the emitted mode is nonisotropic and may be quite difficult to couple into single- or even few-mode fiber. Wavefront aberrations can be corrected using adaptive optics at the classical level by analyzing the wavefront directly (e.g., with a Shack-Hartmann sensor); however, these techniques are not feasible at the single-photon level. We present a new technique for adaptive optics with single photons using a genetic algorithm to optimize collection from point emitters with a deformable mirror. We first demonstrate our technique for improving coupling from a subwavelength pinhole, which simulates isotropic emission from a point source. We then apply our technique \textit{in situ }to InAs/GaAs quantum dots, obtaining coupling increases of up to 50{\%} even in the presence of an artificial source of drift. [Preview Abstract] |
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