Remotely projecting states of photonic temporal modes.

Two-photon time-frequency entanglement is a valuable resource in quantum information. Resolving the wavepacket of ultrashort pulsed single-photons, however, is a challenge. Here, we demonstrate remote spectral shaping of single photon states and probe the coherence properties of two-photon quantum correlations in the time-frequency domain, using engineered parametric down-conversion (PDC) and a quantum pulse gate (QPG) in nonlinear waveguides. Through tailoring the joint spectral amplitude function of our PDC source we control the temporal mode structure between the generated photon pairs and show remote state-projections over a range of time-frequency mode superpositions.

Tomography and Purification of the Temporal-Mode Structure of Quantum Light.

High-dimensional quantum information processing promises capabilities beyond the current state of the art, but addressing individual information-carrying modes presents a significant experimental challenge. Here we demonstrate effective high-dimensional operations in the time-frequency domain of nonclassical light. We generate heralded photons with tailored temporal-mode structures through the pulse shaping of a broadband parametric down-conversion pump. We then implement a quantum pulse gate, enabled by dispersion-engineered sum-frequency generation, to project onto programmable temporal modes, reconstructing the quantum state in seven dimensions. We also manipulate the time-frequency structure by selectively removing temporal modes, explicitly demonstrating the effectiveness of engineered nonlinear processes for the mode-selective manipulation of quantum states.

Direct Characterization of Ultrafast Energy-Time Entangled Photon Pairs.

Energy-time entangled photons are critical in many quantum optical phenomena and have emerged as important elements in quantum information protocols. Entanglement in this degree of freedom often manifests itself on ultrafast time scales, making it very difficult to detect, whether one employs direct or interferometric techniques, as photon-counting detectors have insufficient time resolution. Here, we implement ultrafast photon counters based on nonlinear interactions and strong femtosecond laser pulses to probe energy-time entanglement in this important regime. Using this technique and single-photon spectrometers, we characterize all the spectral and temporal correlations of two entangled photons with femtosecond resolution. This enables the witnessing of energy-time entanglement using uncertainty relations and the direct observation of nonlocal dispersion cancellation on ultrafast time scales. These techniques are essential to understand and control the energy-time degree of freedom of light for ultrafast quantum optics.

High-performance source of spectrally pure, polarization entangled photon pairs based on hybrid integrated-bulk optics.

Entangled photon pair sources based on bulk optics are approaching optimal design and implementation, with high state fidelities, spectral purities and heralding efficiencies, but generally low brightness. Integrated entanglement sources, while providing higher brightness and low-power operation, often sacrifice performance in output state quality and coupling efficiency. Here we present a polarization-entangled pair source based on a hybrid approach of waveguiding and bulk optics, addressing every metric simultaneously. We show 96 % fidelity to the singlet state, 82 % Hong-Ou-Mandel interference visibility, 43 % average Klyshko efficiency, and a high brightness of 2.9 × 106 pairs/(mode·s·mW), while requiring only microwatts of pump power.

Ultrafast time-division demultiplexing of polarization-entangled photons.

Maximizing the information transmission rate through quantum channels is essential for practical implementation of quantum communication. Time-division multiplexing is an approach for which the ultimate rate requires the ability to manipulate and detect single photons on ultrafast time scales while preserving their quantum correlations. Here we demonstrate the demultiplexing of a train of pulsed single photons using time-to-frequency conversion while preserving their polarization entanglement with a partner photon. Our technique converts a pulse train with 2.69 ps spacing to a frequency comb with 307 GHz spacing which may be resolved using diffraction techniques. Our work enables ultrafast multiplexing of quantum information with commercially available single-photon detectors.

Coherent ultrafast measurement of time-bin encoded photons.

Time-bin encoding is a robust form of optical quantum information, especially for transmission in optical fibers. To readout the information, the separation of the time bins must be larger than the detector time resolution, typically on the order of nanoseconds for photon counters. In the present work, we demonstrate a technique using a nonlinear interaction between chirped entangled time-bin photons and shaped laser pulses to perform projective measurements on arbitrary time-bin states with picosecond-scale separations. We demonstrate a tomographically complete set of time-bin qubit projective measurements and show the fidelity of operations is sufficiently high to violate the Clauser-Horne-Shimony-Holt-Bell inequality by more than 6 standard deviations.

Diagnosis and treatment of Mirizzi syndrome: 23-year Mayo Clinic experience.

BACKGROUND: Mirizzi syndrome (MS) is characterized by extrinsic compression of the common hepatic duct by stones impacted in the cystic duct or gallbladder neck. Open cholecystectomy (OC) has been the standard treatment; however, laparoscopy has challenged this approach. STUDY DESIGN: The objective of this study was to review our clinical experience with MS since the introduction of laparoscopic cholecystectomy (LC) and determine the impact of alternative approaches. We conducted a retrospective review of patients with MS from January 1987 to December 2009. RESULTS: There were 36 patients with MS among 21,450 cholecystectomies (frequency 0.18%). Seventeen were women. The most common presenting symptoms were abdominal pain (n = 23) and jaundice (n = 19). Preoperative diagnostic studies included ultrasonography (n = 27), CT (n = 24), and endoscopic retrograde cholangiopancreatography (n = 32). Cholecystectomy was performed in 35 patients; LC was initiated in 15 and OC in 21. Conversion rate from LC to OC was 67%. Five patients who had successful LC had type I MS. Of the patients who underwent LC with conversion or OC, 14 had type I and 16 had type II MS. The cystic duct for type I and the bile duct for type II MS were managed diversely according to surgeon's preference. There was no operative mortality. Morbidity was 31% with Clavien class I in 2, IIIa in 4, IIIb in 1, and IV in 3 patients. Mean hospitalization was 9 days (range 2 to 40 days). Mean follow-up was 37 months (range 1 to 187 months). CONCLUSIONS: Low incidence and nonspecific presentation of MS precludes referral and substantive individual experience. Although LC may be applicable in selected patients with type I MS, OC remains the standard of care.