SESSION 4: Quantum optics

Chair: (Alberto Marino)
3:15pm - 3:45pmMichael G. Raymer , University of Oregon
High-efficiency demultiplexing of quantum information in temporal modes
Abstract. Information can be encoded in single photons using temporal modes (sets of field-orthogonal wave-packet shapes). Temporal modes span a high-dimensional quantum state space and integrate into existing single-mode fiber communication networks, thus creating a new framework for quantum information science. A major challenge to achieving full control of temporal-mode states is their multiplexing and demultiplexing with zero crosstalk. Such add/drop functionality can be achieved by frequency conversion (FC) via nonlinear wave mixing, which can exchange the quantum states between two narrow spectral bands in a temporal-mode-selective manner. By tailoring the shape of the pump laser pulse and the phase-matching conditions of a second-order nonlinear optical medium, one can achieve moderate selectivity for different temporally orthogonal wave packets. To exceed this limit, we demonstrate a two-stage “Ramsey” interferometric FC scheme [1], predicted by theory to reach near-perfect (100%) selectivity. Using the two-stage scheme, we demonstrate a large increase over the single-stage selectivity limit, for the first three natural (“Schmidt”) modes of the FC process. This result paves the way for implementing arbitrary single-photon unitary operations, and thus various protocols such as QKD, in the temporal-mode basis. 1. “High-selectivity quantum pulse gating of photonic temporal modes using all-optical Ramsey interferometry,” D. V. Reddy and M. G. Raymer, Optica, 5, 423 (2018)
3:45pm - 4:15pmSteve Young, Sandia National Laboratories
General modeling framework for quantum photodetectors
Abstract. Photodetection plays a key role in basic science and technology, with exquisite performance having been achieved down to the single photon level. Further improvements in photodetectors would open new possibilities across a broad range of scientific disciplines, and enable new types of applications. However, it is still unclear what is possible in terms of ultimate performance, and what properties are needed for a photodetector to achieve such performance. Here we present a general modeling framework for single- and few- photon detectors wherein the entire detection process - including the photon field, environmental coupling, and measurement output - is treated holistically and quantum mechanically. The formalism naturally handles field states with single or multiple photons as well as arbitrary detector configurations. It is explicitly constructed to provide performance characteristics and naturally furnishes a mathematical definition of ideal photodetector performance. The framework reveals how specific photodetector architectures and physical realizations introduce limitations and tradeoffs for various performance metrics, providing guidance for optimization and design.
4:15pm - 4:45pmSofiane Merkouche, University of Oregon
Entangled-state measurements based on mode-resolved two-photon sum-frequency generation
Abstract. Projective measurements onto entangled quantum states (commonly referred to as "entangled measurements") are an essential tool for many quantum information processing applications, for example quantum repeaters and quantum-state teleportation. The most well-studied such measurement is the Bell-state measurement for two qubits. Here, we introduce a two-photon multi-mode entangled-state measurement scheme based upon sum-frequency generation (SFG) followed by mode-resolved single-photon detection. We show that the mode-resolved detection of the output of a two-photon SFG process acts as a projective measurement onto the two-photon entangled state produced by the time-reversed parametric downconversion process in the perturbative limit. We analyze the applicability of such a measurement both for temporal- and spatial-mode entanglement, and show how this can be exploited for high-dimensional quantum teleportation, entanglement swapping, and quantum illumination.

SQuInT Chief Organizer
Akimasa Miyake, Associate Professor

SQuInT Local Organizers
Rafael Alexander, Postdoctoral Fellow
Chris Jackson, Postdoctoral Fellow

SQuInT Administrator
Gloria Cordova
505 277-1850

SQuInT Assistant
Wendy Jay

SQuInT Founder
Ivan Deutsch, Regents' Professor, CQuIC Director

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