We demonstrate a compressed sensing, photon counting lidar system based on the single-pixel camera. Our technique recovers both depth and intensity maps from a single under-sampled set of incoherent, linear projections of a scene of interest at ultra-low light levels around 0.5 picowatts. Only two-dimensional reconstructions are required to image a three-dimensional scene. We demonstrate intensity imaging and depth mapping at 256 × 256 pixel transverse resolution with acquisition times as short as 3 seconds. We also show novelty filtering, reconstructing only the difference between two instances of a scene. Finally, we acquire 32 × 32 pixel real-time video for three-dimensional object tracking at 14 frames-per-second.

In a recent Letter, Brunner and Simon proposed an interferometric scheme using imaginary weak values with a frequency-domain analysis to outperform standard interferometry in longitudinal phase shifts [Phys. Rev. Lett105, 010405 (2010)]. Here we demonstrate an interferometric scheme combined with a time-domain analysis to measure longitudinal velocities. The technique employs the near-destructive interference of non-Fourier limited pulses, one Doppler shifted due to a moving mirror in a Michelson interferometer. We achieve a velocity measurement of 400 fm/s and show our estimator to be efficient by reaching its Cramér-Rao bound.

High-dimensional Hilbert spaces used for quantum communication channels offer the possibility of large data transmission capabilities. We propose a method of characterizing the channel capacity of an entangled photonic state in high-dimensional position and momentum bases. We use this method to measure the channel capacity of a parametric down-conversion state by measuring in up to 576 dimensions per detector. We achieve a channel capacity over 7 bits/photon in either the position or momentum basis. Furthermore, we provide a correspondingly high-dimensional separability bound that suggests that the channel performance cannot be replicated classically.

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We implement a double-pixel compressive-sensing camera to efficiently characterize, at high resolution, the spatially entangled fields that are produced by spontaneous parametric down-conversion. This technique leverages sparsity in spatial correlations between entangled photons to improve acquisition times over raster scanning by a scaling factor up to n 2 = logðnÞ for n-dimensional images. We image at resolutions up to 1024 dimensions per detector and demonstrate a channel capacity of 8.4 bits per photon. By comparing the entangled photons' classical mutual information in conjugate bases, we violate an entropic Einstein-Podolsky-Rosen separability criterion for all measured resolutions. More broadly, our result indicates that compressive sensing can be especially effective for higher-order measurements on correlated systems.

We experimentally demonstrate a photon-counting, single-pixel, laser radar camera for 3D imaging where transverse spatial resolution is obtained through compressive sensing without scanning. We use this technique to image through partially obscuring objects, such as camouflage netting. Our implementation improves upon pixel-array based designs with a compact, resource-efficient design and highly scalable resolution. © 2011 Optical Society of America OCIS codes: 280.3640, 100.6890, 110.3010, 110.3080. The use of lasers for ranging (lidar) has greatly improved spatial and longitudinal resolution in ranged detectors [1]. Traditional lidar systems are singlepixel devices that obtain transverse resolution via scanning. In the past decade, there has been much interest in replacing scanning with spatially resolving detectors to produce ranged cameras [2-4]. These devices rapidly acquire three-dimensional images and utilize range gating to reveal objects obscured behind foliage or other camouflaging materials. The primary challenge is developing detectors with useful spatial resolution, high sensitivity, and fast timing. The most successful approach to date is the use of arrays of avalanche photo-diodes operating in the spirit of a CCD camera. A variety of high resolution systems have been brought to market with linear mode avalanche photodiode (APD) arrays [5]. For best performance, however, it is desirable to instead operate the APDs in geiger-mode to count discrete, single-photon arrivals. These photon-counting detectors have single-photon precision and sensitivity that approaches the shot noise limit with subnano-second timing. Such an array was developed for the state-of-the-art Jigsaw system created at MIT Lincoln Labs [6], which has been field tested with impressive results. The Jigsaw sensor consists of a 32 × 32 array of APDs detecting single-photon arrivals in a time-of-flight (TOF) lidar configuration.While single geiger-mode APDs are well developed, high resolution arrays are difficult to fabricate and remain primarily a research subject. As such, they present pragmatic difficulties. The highest resolution commercially available sensor is only 32 × 32 pixels, with 32 × 128 in development [7,8]. Lincoln Labs has reported up to 64 × 256 pixels [9,10]. Jigsaw must incorporate prism-based scanning to improve its resolution and field-of-view. Current arrays also have limited spectral range with peak quantum efficiency in the midvisible spectrum. For ranging, significant supporting equipment is required to correlate each pixel with illuminating pulses. Because individual pixels are small and optical flux must be distributed across the entire array, shot noise is significant. At present, such arrays are generally resource heavy in development and implementation.We show that these difficulties can be resolved by applying single-pixel camera technology [11] to generate transverse spatial resolution. This technique, pioneered by Baraniuk, uses compressive sensing to detect images with a single detector [12]. Appro...

Here we demonstrate quantum interference of photons on a Silicon chip produced from a single ring resonator photon source. The source is seamlessly integrated with a Mach-Zehnder interferometer, which path entangles degenerate bi-photons produced via spontaneous four wave mixing in the Silicon ring resonator. The resulting bi-photon N00N state is controlled by varying the relative phase of the integrated Mach-Zehnder interferometer, resulting in high two-photon interference visibilities of V~96%. Furthermore, we show that the interference can be produced using pump wavelengths tuned to all of the ring resonances accessible with our tunable lasers (C+L band). This work is a key demonstration towards the simplified integration of multiple photon sources and quantum circuits together on a monolithic chip, in turn, enabling quantum information chips with much greater complexity and functionality.

We present a compressive sensing protocol that tracks a moving object by removing static components from a scene. The implementation is carried out on a ghost imaging scheme to minimize both the number of photons and the number of measurements required to form a quantum image of the tracked object. This procedure tracks an object at low light levels with fewer than 3% of the measurements required for a raster scan, permitting us to more effectively use the information content in each photon.a)