49 research outputs found

    Programmable multiport optical circuits in opaque scattering materials

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    We propose and experimentally verify a method to program the effective transmission matrix of general multiport linear optical circuits in random multiple-scattering materials by phase modulation of incident wavefronts. We demonstrate the power of our method by programming linear optical circuits in white paint layers with 2 inputs and 2 outputs, and 2 inputs and 3 outputs. Using interferometric techniques we verify our ability to program any desired phase relation between the outputs. The method works in a deterministic manner and can be directly applied to existing wavefront-shaping setups without the need of measuring a transmission matrix or to rely on sensitive interference measurements.Comment: 14 pages, 7 figure

    Programmable two-photon quantum interference in 10310^3 channels in opaque scattering media

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    We investigate two-photon quantum interference in an opaque scattering medium that intrinsically supports 10610^6 transmission channels. By adaptive spatial phase-modulation of the incident wavefronts, the photons are directed at targeted speckle spots or output channels. From 10310^3 experimentally available coupled channels, we select two channels and enhance their transmission, to realize the equivalent of a fully programmable 2×22\times2 beam splitter. By sending pairs of single photons from a parametric down-conversion source through the opaque scattering medium, we observe two-photon quantum interference. The programmed beam splitter need not fulfill energy conservation over the two selected output channels and hence could be non-unitary. Consequently, we have the freedom to tune the quantum interference from bunching (Hong-Ou-Mandel-like) to antibunching. Our results establish opaque scattering media as a platform for high-dimensional quantum interference that is notably relevant for boson sampling and physical-key-based authentication

    Large-scale purification of factor VIII by affinity chromatography: optimization of process parameters

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    The optimization of a new process for the extraction of human coagulation factor VIII (FVIII) from plasma with the tailor-made affinity matrix dimethylaminopropylcarbamylpentyl-Sepharose CL-4B (C3---C5 matrix) is described. First, plasma is applied to DEAE-Sephadex A-50 anion exchanger in order to separate a number of proteins, including coagulation factors II, IX and X (prothrombin complex), from FVIII. Subsequently, the unbound fraction of the ion exchanger, containing FVIII, is contacted with the C3---C5 affinity matrix. Optimization of the FVIII affinity chromatographic procedure is accomplished in terms of the ligand density of the matrix, adsorption mode (batch-wise versus column-wise adsorption and matrix to plasma ratio), and conditions of pH and conductivity to be applied on washing and desorption. In scale-up experiments, by processing 20 1 of plasma, the recovery (340 U VIII:C/kg plasma) and the specific activity (s.a.) (1.2 U VIII:C/mg protein) are better than those obtained by cryoprecipitation (recovery 300 U VIII:C/kg plasma, s.a. O.3 U VIII:C/mg protein). The newly developed process using the specially designed C3---C5 affinity matrix has potential application in the process-scale purification of FVIII

    8x8 Reconfigurable quantum photonic processor based on silicon nitride waveguides

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    The development of large-scale optical quantum information processing circuits ground on the stability and reconfigurability enabled by integrated photonics. We demonstrate a reconfigurable 8x8 integrated linear optical network based on silicon nitride waveguides for quantum information processing. Our processor implements a novel optical architecture enabling any arbitrary linear transformation and constitutes the largest programmable circuit reported so far on this platform. We validate a variety of photonic quantum information processing primitives, in the form of Hong-Ou-Mandel interference, bosonic coalescence/anticoalescence and high-dimensional single-photon quantum gates. We achieve fidelities that clearly demonstrate the promising future for large-scale photonic quantum information processing using low-loss silicon nitride.Comment: Added supplementary materials, extended introduction, new figures, results unchange

    Transient and sustained incentive effects on electrophysiological indices of cognitive control in younger and older adults

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    Preparing for upcoming events, separating task-relevant from task-irrelevant information and efficiently responding to stimuli all require cognitive control. The adaptive recruitment of cognitive control depends on activity in the dopaminergic reward system as well as the frontoparietal control network. In healthy aging, dopaminergic neuromodulation is reduced, resulting in altered incentive-based recruitment of control mechanisms. In the present study, younger adults (18–28 years) and healthy older adults (66–89 years) completed an incentivized flanker task that included gain, loss, and neutral trials. Event-related potentials (ERPs) were recorded at the time of incentive cue and target presentation. We examined the contingent negative variation (CNV), implicated in stimulus anticipation and response preparation, as well as the P3, which is involved in the evaluation of visual stimuli. Both younger and older adults showed transient incentive-based modulation of CNV. Critically, cue-locked and target-locked P3s were influenced by transient and sustained effects of incentives in younger adults, while such modulation was limited to a sustained effect of gain incentives on cue-P3 in older adults. Overall, these findings are in line with an age-related reduction in the flexible recruitment of preparatory and target-related cognitive control processes in the presence of motivational incentives

    Programmable quantum interference in massively multichannel networks

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    Multiphoton quantum correlations are crucial for quantum information processing and quantum communication protocols in linear optical networks. For large-scale implementation of quantum information processing, such as quantum simulators, boson sampling or programmable quantum logic gates, a programmable functionality of a large multichannel network is required. In this thesis, we describe and demonstrate programmable quantum interference between multiple single-photon states in massively multichannel networks. Using a theoretical analysis we first show that losses in optical networks, which are unavoidable in experiments, introduce new freedom, in that the functionality of the network, and thus also quantum interference in there, is programmable to an extent not possible with lossless networks. We introduce a method to program the functionality of general multichannel linear optical networks by phase modulation of incident wavefronts, which we apply to opaque scattering media as well as integrated optics. To demonstrate quantum interference in massively multichannel networks we require a source of multiple indistinguishable single-photon states. Therefore, we have constructed and characterized a versatile quantum light source based on spontaneous parametric down-conversion. For the first time, we demonstrate two-photon quantum interference in a massively multichannel linear optical network realized in an opaque scattering medium. Using adaptive phase-modulation of the incident photons, the scattering medium is transformed to behave as a fully programmable beam splitter that is freely tunable in functionality. Exploiting this freedom, we not only show the well-known Hong-Ou-Mandel bunching of photons, but also demonstrate that this bunching can be made to vanish, or be transformed into antibunching. Our results establish opaque scattering media as a platform for massively multichannel linear optical networks with programmable quantum correlations. Finally, the high number of available channels offered by opaque scattering media can directly be employed for authentication of secure communication. We present an authenticated protocol for quantum key distribution that removes the need of an initial shared secret for authentication. Moreover, we introduce and demonstrate the first protocol for authenticated and asymmetric quantum communication, based on the quantum-secure readout of a physical unclonable function