A5019874230- Quantum Information and Cryptography
- Quantum Mechanics and Applications
- Quantum optics and atomic interactions
- Laser-Matter Interactions and Applications
- Quantum Computing Algorithms and Architecture
- Photonic and Optical Devices
- Advanced Fiber Laser Technologies
- Mechanical and Optical Resonators
- Neural Networks and Reservoir Computing
- Solid State Laser Technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Orbital Angular Momentum in Optics
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Photorefractive and Nonlinear Optics
- Particle Accelerators and Free-Electron Lasers
- Advanced Fluorescence Microscopy Techniques
- Molecular Communication and Nanonetworks
- Advanced Optical Sensing Technologies
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Laser-Plasma Interactions and Diagnostics
- Earthquake Detection and Analysis
- Random lasers and scattering media
- Photonic Crystals and Applications
Oak Ridge National Laboratory
2011-2025
Quantum Science Center
2009-2023
Qubitekk (United States)
2019
University of Tennessee at Knoxville
2011-2012
Southern Illinois University Edwardsville
1998-2000
University of Rochester
1995-1999
A model is presented to describe spontaneous type-II parametric down-conversion pumped by a broadband source. This process differs from the familiar cw-pumped in that broader range of pump energies available for down-conversion. The properties nonlinear crystal determine how these are distributed into down-converted photons. Because two photons polarized along different axes, they have spectral characteristics and no longer exactly anticorrelated. As bandwidth increased, this effect becomes...
Multiphoton states constructed from photon pairs generated in the process of spontaneous parametric down-conversion possess frequency and space-time correlations that may carry undesired distinguishing information. It is shown these be eliminated if certain conditions source configuration are satisfied. For cases which cannot satisfied because experimental constraints, it reduced through proper choices crystal length pump bandwidth. The advantage such engineering yields much higher count...
Continuous-variable quantum key distribution (CV-QKD) protocols based on coherent detection have been studied extensively in both theory and experiment. In all the existing implementations of CV-QKD, signal local oscillator (LO) are generated from same laser propagate through insecure channel. This arrangement may open security loopholes also limit potential applications CV-QKD. this paper, we propose demonstrate a pilot-aided feedforward data recovery scheme which enables reliable using...
A complete Bell-state measurement is not possible using only linear-optic elements, and most schemes achieve a success rate of no more than 50%, distinguishing, for example, two the four Bell states but returning degenerate results other two. It shown here that introduction pair ancillary entangled photons improves to 75%. More generally, addition ${2}^{N}\ensuremath{-}2$ yields with $1\ensuremath{-}1/{2}^{N}$.
We present results of a bright polarization-entangled photon source operating at 1552 nm via type-II collinear degenerate spontaneous parametric down-conversion in periodically poled potassium titanyl phosphate crystal. report conservative inferred pair generation rate $123\text{ }000\text{ }\text{ }\mathrm{pairs}/\mathrm{s}/\mathrm{mW}$ into collection modes. Minimization spectral and spatial entanglement was achieved by group velocity matching the pump, signal, idler modes through properly...
We characterize a periodically poled KTP crystal that produces an entangled, two-mode, squeezed state with orthogonal polarizations, nearly identical, factorizable frequency modes, and few photons in unwanted modes. focus the pump beam to create circular joint spectral probability distribution between two After disentangling we observe Hong-Ou-Mandel interference raw (background corrected) visibility of 86 % (95 %) when 8.6 nm bandwidth filter is applied. measure second order photon...
We describe and experimentally demonstrate a more practical three-party quantum secret sharing (QSS) protocol using polarization-entangled photon pairs. The source itself serves as an active participant can switch between the required states by modulating pump beam only, thereby making less susceptible to loss amenable fast switching. derive security proof based on key distribution, demonstrating our QSS be secure against both eavesdropping dishonest participants. Compared three-photon...
Secret sharing allows a trusted party (the dealer) to distribute secret group of players, who can only access the cooperatively. Quantum (QSS) protocols could provide unconditional security based on fundamental laws in physics. While general proof has been established recently an entanglement-based QSS protocol, tolerable channel loss is unfortunately rather small. Here we propose continuous variable protocol using conventional laser sources and homodyne detectors. In this Gaussian-modulated...
We report complete measurement of the spectral properties photon pairs generated via spontaneous parametric downconversion. The measurements, which include not only single-photon spectra but also two-photon joint spectra, were performed for both cw and ultrafast-pumping configurations. In agreement with theoretical predictions, ultrafast-pumped case reveal asymmetries that are present pumping.
In the Gaussian-modulated coherent-states (GMCS) quantum key distribution (QKD) protocol, Alice prepares states actively: For each transmission, generates a pair of Gaussian-distributed random numbers, encodes them on weak coherent pulse using optical amplitude and phase modulators, then transmits to Bob. Here we propose passive state preparation scheme thermal source. our scheme, splits output source into two spatial modes beam splitter. She measures one mode locally conjugate homodyne...
We report a novel Bell-state synthesizer in which an interferometric entanglement concentration scheme is used. An initially mixed polarization state from type-II spontaneous parametric down-conversion becomes entangled after the concentrator. This universal sense that output not affected by spectral filtering, crystal thickness, and, most importantly, choice of pump source. It also robust against environmental disturbance and more general state, partially mixed$-$partially can be readily...
We present a novel interferometric technique for suppressing distinguishing information in the space-time component of state vector an entangled pair photons by providing two indistinguishable ways each photon to occupy any given mode. demonstrate this method using spontaneous parametric down-conversion generate with least consistent set modes available. The also allows preparation highly provided certain criteria are met.
We report a fourth-order interference experiment in which pairs of photons produced parametric down-conversion pumped by short optical pulses interfere Hong-Ou-Mandel interferometer. The visibility the pattern is reduced for larger pump bandwidths. This effect can be understood terms spectral distinguishability photon pairs. restored blocking distinguishing information with filter.
The challenge of optimizing the emission into single spatial modes photons from spontaneous parametric down-conversion is addressed perspective entanglement. It shown that single-mode coupling most efficient in absence Evidence relationship between entanglement and pump focusing revealed through experimental results, numerical simulations show are optimized under nearly identical parameters.
The rising demand for transmission capacity in optical networks has motivated steady interest expansion beyond the standard C-band (1530-1565 nm) into adjacent L-band (1565-1625 an approximate doubling of a single stroke. However, context quantum networking, yet to be fully leveraged with suite advanced tools characterization and management available from classical lightwave communications. In this work, we demonstrate ultrabroadband two-photon source integrating both C- wavelength-selective...
It is a well-known and remarkable fact that in certain coincidence photon-counting experiments with cw-pumped parametric down-converters, the effects of group-velocity dispersion arising from media interposed between source detectors are completely canceled, even if physically affect only one photons pair. Recently Perina et al. [Phys. Rev. A 59, 2359 (1999)] showed this phenomenon does not occur when classical timing information available about arrival individual at detectors, as case...
We study the conditional preparation of single photons based on parametric downconversion, where detection one photon from a given pair heralds existence in conjugate mode. derive conditions modal characteristics pairs, which ensure that conditionally prepared are quantum-mechanically pure. propose specific experimental techniques yield pairs ideally suited for single-photon preparation.
It is known that photons produced by spontaneous parametric down-conversion can be coupled into optical fibers more efficiently focusing the pump field. We find in type-II causes of ordinary and extraordinary polarization to acquire very different angular spreads, which amounts spatial information distinguishes between states. Numerical studies predict collected a detector or quantum channel will predominantly one degree entanglement lessened some cases.
We report a two-photon quantum interference experiment in which the detected individual photons have quite different properties. The is observed even when no effort made to mask distinguishing features before are detected. results can be explained only terms of indistinguishable amplitudes.
We use a multimode description of polarization-encoded qubits to analyze the quantum teleportation protocol. Specifically, we investigate how fidelity depends on spectral correlations inherent polarization-entangled photons generated by type-II spontaneous parametric down conversion. find that maximal obtainable entanglement carried joint probability amplitude, result which quantify for case spectrum approximated correlated Gaussian function. contrast these results with similar analysis...
Thin carbon foils are used as strippers for charge exchange injection into high intensity proton rings. However, the stripping become radioactive and produce uncontrolled beam loss, which is one of main factors limiting power in Recently, we presented a scheme laser an ${\mathrm{H}}^{\ensuremath{-}}$ Spallation Neutron Source (SNS) ring. First, atoms converted to ${\mathrm{H}}^{0}$ by magnetic field, then excited from ground state upper levels laser, states protons field. In this paper...
We examine how spectral entanglement in polarization-entangled photon states generated from bulk-crystal, spontaneous parametric down-conversion affects the success of swapping and type-I fusion gates. quantify gates by calculating bipartite concurrence residual tangle, respectively, terms joint probability amplitudes initial broad-bandwidth states. find that both polarization-entanglement measures depend strongly on entanglement, as well configuration independent sources. Specifically, when...