167 research outputs found
Spectral Hong-Ou-Mandel Effect between a Heralded Single-Photon State and a Thermal Field: Multiphoton Contamination and the Nonclassicality Threshold
No full textThe Hong-Ou-Mandel (HOM) effect is crucial for quantum information processing, and its visibility determines the system's quantum-classical characteristics. In an experimental and theoretical study of the spectral HOM effect between a thermal field and a heralded single-photon state, we demonstrate that the HOM visibility varies dependent on the relative photon statistics of the interacting fields. Our findings reveal that multiphoton components in a heralded state get engaged in quantum interference with a thermal field, resulting in improved visibilities at certain mean photon numbers. We derive a theoretical relationship for the HOM visibility as a function of the mean photon number of the thermal field and the thermal part of the heralded state. We show that the nonclassicality degree of a heralded state is reflected in its HOM visibility with a thermal field; our results establish a lower bound of 41.42% for the peak visibility, indicating the minimum assignable degree of nonclassicality to the heralded state. This research enhances our understanding of the HOM effect and its application to high-speed remote secret key sharing, addressing security concerns due to multiphoton contamination in heralded states
Hong-Ou-Mandel Effect Between a Thermal Field and a Heralded Single-Photon State: Improved Visibility by Multiphoton Components
No full textEnhancing upconversion with space–time entanglement: from twin photons to twin-beams
No full textWe investigate the use of entangled photons generated by parametric downconversion to improve the efficiency of second harmonic generation (SHG). Using a fully three-dimensional model for the nonlinear interactions, we obtain quantitative predictions of the efficiency of quantum-enhanced SHG and identify the critical parameters to optimize the process. By a careful control of the spatial and temporal degrees of freedom, we demonstrate a robust quantum advantage, extending to illumination fluxes well above the limits traditionally considered in the literature. Our analysis offers valuable insights into the ongoing debate on quantum-enhanced two-photon processes and helps establish their usefulness in applications
Single-frequency optical parametric oscillator intracavity-pumped by a visible VECSEL for low-noise down-conversion to 1.55 μm
No full textWe report, to the best of our knowledge, the first optical parametric oscillator (OPO) pumped by a visible AlGaInP-based vertical-external-cavity surface-emitting laser (VECSEL). Tunable emission over 1155-1300 nm in the signal and 1474-1718 nm in the idler are observed by temperature adjustment of a 40 mm-long 5%-MgO:PPLN crystal intracavity-pumped at 690 nm. When optimized for low oscillation threshold, and by implementing resonant idler output-coupling (TOC = 1.7%), extracted output powers of 26.2 mW (signal) and 5.6 mW (idler; one-way) are measured, corresponding to a total down-conversion efficiency and extraction efficiency of 70.2% and 43%, respectively. Further, a total down-conversion efficiency of 72.1% is achieved in the absence of idler output-coupling. Of particular interest for high-precision applications, including quantum optics experiments and squeezed light generation, high stability and single-frequency operation are also demonstrated. We measure RMS stabilities of 0.4%, 1.8% and 2.3% for the VECSEL fundamental, signal and idler, with (resolution-limited) frequency linewidths of 2.5 MHz (VECSEL) and 7.5 MHz (signal and idler)
Counterpropagating frequency mixing with terahertz waves in diamond
Get PDFFrequency conversion by means of Kerr nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR, and mid-IR spectral regions. Here we show that wave mixing of an optical field and a terahertz wave can be achieved in diamond, resulting in the frequency conversion of the terahertz radiation either by sum-or difference-frequency generation. In the latter case, we show that this process is phase matched and most efficient in a counterpropagating geometry. (C) 2013 Optical Society of America</p
Multipartite d-level photon cluster states and practical entanglement detection through witness operators
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Integrated sources of photon quantum states based on nonlinear optics
Get PDFThe ability to generate complex optical photon states involving entanglement between multiple optical modes is not only critical to advancing our understanding of quantum mechanics but will play a key role in generating many applications in quantum technologies. These include quantum communications, computation, imaging, microscopy and many other novel technologies that are constantly being proposed. However, approaches to generating parallel multiple, customisable bi- and multi-entangled quantum bits (qubits) on a chip are still in the early stages of development. Here, we review recent developments in the realisation of integrated sources of photonic quantum states, focusing on approaches based on nonlinear optics that are compatible with contemporary optical fibre telecommunications and quantum memory infrastructures as well as with chip-scale semiconductor technology. These new and exciting platforms hold the promise of compact, low-cost, scalable and practical implementations of source s for the generation and manipulation of complex quantum optical states on a chip, which will play a major role in bringing quantum technologies out of the laboratory and into the real world
Quantum states of light for quantum metrology, computing and communication (Conference Presentation)
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