538 research outputs found
Enhancing entanglement detection of quantum optical frequency combs via stimulated emission
We investigate the performance of a certain nonclassicality identifier,
expressed via integrated second-order intensity moments of optical fields, in
revealing bipartite entanglement of quantum-optical frequency combs (QOFCs),
which are generated in both spontaneous and stimulated parametric
down-conversion processes. We show that, by utilizing that nonclassicality
identifier, one can well identify the entanglement of the QOFC directly from
the experimentally measured intensity moments without invoking any state
reconstruction techniques or homodyne detection. Moreover, we demonstrate that
the stimulated generation of the QOFC improves the entanglement detection of
these fields with the nonclassicality identifier. Additionally, we show that
the nonclassicality identifier can be expressed in a factorized form of
detectors quantum efficiencies and the number of modes, if the QOFC consists of
many copies of the same two-mode twin beam. As an example, we apply the
nonclassicality identifier to two specific types of QOFC, where: (i) the QOFC
consists of many independent two-mode twin beams with non-overlapped spatial
frequency modes, and (ii) the QOFC contains entangled spatial frequency modes
which are completely overlapped, i.e., each mode is entangled with all the
remaining modes in the system. We show that, in both cases, the nonclassicality
identifier can reveal bipartite entanglement of the QOFC including noise, and
that it becomes even more sensitive for the stimulated processes.Comment: 11 p., 8 fig
Theory of three-pulse photon echo spectroscopy with dual frequency combs
A theoretical analysis is carried out for the recently developed three-pulse
photon echo spectroscopy employing dual frequency combs (DFC) as the light
sources. In this method, the molecular sample interacts with three pulse trains
derived from the DFC and the generated third-order signal is displayed as a
two-dimensional (2D) spectrum that depends on the waiting time introduced by
employing asynchronous optical sampling method. Through the analysis of the
heterodyne-detected signal interferogram using a local oscillator derived from
one of the optical frequency combs, we show that the 2D spectrum closely
matches the spectrum expected from a conventional approach with four pulses
derived from a single femtosecond laser pulse and the waiting time between the
second and third field-matter interactions is given by the down-converted
detection time of the interferogram. The theoretical result is applied to a
two-level model system with solvation effect described by solvatochromic
spectral density. The model 2D spectrum reproduces spectral features such as
the loss of frequency correlation, dephasing, and spectral shift as a function
of the population time. We anticipate that the present theory will be the
general framework for quantitative descriptions of DFC-based nonlinear optical
spectroscopy.Comment: 20 pages, 2 figures are included in the PDF fil
Quantitative Complementarity of Wave-Particle Duality
To test the principle of complementarity and wave-particle duality
quantitatively, we need a quantum composite system that can be controlled by
experimental parameters. Here, we demonstrate that a double-path interferometer
consisting of two parametric downconversion crystals seeded by coherent idler
fields, where the generated coherent signal photons are used for quantum
interference and the conjugate idler fields are used for which-path detectors
with controllable fidelity, is useful for elucidating the quantitative
complementarity. We show that the source purity is tightly bounded by
the entanglement measure by the relation and the
visibility and detector fidelity determine the coherence of the
quantons, i.e., . The quantitative complementarity of the double-path
interferometer we developed recently is explained in terms of the
quanton-detector entanglement or quanton source purity that are expressed as
functions of injected seed photon numbers. We further suggest that the
experimental scheme utilizing two stimulated parametric downconversion
processes is an ideal tool for investigating and understanding wave-particle
duality and complementarity quantitatively.Comment: 14 pages, 5 figure
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Phase-Coherent Multilevel Two-Photon Transitions in Cold Rb Atoms: Ultrahigh-Resolution Spectroscopy via Frequency-Stabilized Femtosecond Laser
A two-photon transition in cold Rb atoms will be probed with a phase-coherent wide bandwidth femtosecond laser comb. Frequency domain analysis yields a high-resolution picture where phase coherence among various transition pathways through different intermediate states produces interference effects on the resonantly enhanced transition probability. This result is supported by the time domain Ramsey interference effect. The two-photon transition spectrum is analyzed in terms of the pulse repetition rate and carrier frequency offset, leading to a cold-atom-based frequency stabilization scheme for both degrees of freedom of the femtosecond laser
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Sub-Doppler Molecular-Iodine Transitions near the Dissociation Limit (523β498 nm)
A widely tunable and high-resolution spectrometer based on a frequency-doubled Ti:sapphire laser was used to explore sub-Doppler transitions of iodine molecules in the wavelength range 523β498 nm. The wavelength dependence of the hyperfine transition linewidth of iodine was mapped out in this region, and the narrowest linewidth was βΌ4 kHz near 508 nm. The hyperfine-resolved patterns were found to be largely modified toward the dissociation limit. The observed excellent signal-to-noise ratio should lead to high-quality optical frequency standards that are better than those of the popular 532-nm system
Selective uptake of epidermal growth factor-conjugated gold nanoparticle (EGF-GNP) facilitates non-thermal plasma (NTP)-mediated cell death
Non-thermal atmospheric pressure plasma (NTP) has been shown to induce cell death in various mammalian cancer cells. Accumulated evidence also shows that NTP could be clinically used in cancer therapy. However, the current NTP-based applications lack target specificity. Here, a novel method in NTP-mediated cancer therapeutics was described with enhanced target specificity by treating EGF (epidermal growth factor)-conjugated GNP (gold nanoparticle). The treatment with EGF-conjugated GNP complex, followed by NTP irradiation showed selective apoptosis of cells having receptor-mediated endocytosis. NTP triggered gamma-H2AX elevation which is a typical response elicited by DNA damage. These results suggest that EGF-conjugated GNP functions as an important adjuvant which gives target specificity in applications of conventional plasma therapy.111Ysciescopu
Human dopamine receptor nanovesicles for gate-potential modulators in high-performance field-effect transistor biosensors
The development of molecular detection that allows rapid responses with high sensitivity and selectivity remains challenging. Herein, we demonstrate the strategy of novel bio-nanotechnology to successfully fabricate high-performance dopamine (DA) biosensor using DA Receptor-containing uniform-particle-shaped Nanovesicles-immobilized Carboxylated poly(3,4-ethylenedioxythiophene) (CPEDOT) NTs (DRNCNs). DA molecules are commonly associated with serious diseases, such as Parkinson's and Alzheimer's diseases. For the first time, nanovesicles containing a human DA receptor D1 (hDRD1) were successfully constructed from HEK-293 cells, stably expressing hDRD1. The nanovesicles containing hDRD1 as gate-potential modulator on the conducting polymer (CP) nanomaterial transistors provided high-performance responses to DA molecule owing to their uniform, monodispersive morphologies and outstanding discrimination ability. Specifically, the DRNCNs were integrated into a liquid-ion gated field-effect transistor (FET) system via immobilization and attachment processes, leading to high sensitivity and excellent selectivity toward DA in liquid state. Unprecedentedly, the minimum detectable level (MDL) from the field-induced DA responses was as low as 10β
pM in real- time, which is 10 times more sensitive than that of previously reported CP based-DA biosensors. Moreover, the FET-type DRNCN biosensor had a rapid response time (<1β
s) and showed excellent selectivity in human serum
Multi-ensemble metrology by programming local rotations with atom movements
Current optical atomic clocks do not utilize their resources optimally. In
particular, an exponential gain could be achieved if multiple atomic ensembles
were to be controlled or read-out individually, even without entanglement.
However, controlling optical transitions locally remains an outstanding
challenge for neutral atom based clocks and quantum computing platforms. Here
we show arbitrary, single-site addressing for an optical transition via
sub-wavelength controlled moves of tweezer-trapped atoms, which we perform with
fidelity and with crosstalk to non-addressed atoms. The
scheme is highly robust as it relies only on relative position changes of
tweezers and requires no additional addressing beams. Using this technique, we
implement single-shot, dual-quadrature readout of Ramsey interferometry using
two atomic ensembles simultaneously, and show an enhancement of the usable
interrogation time at a given phase-slip error probability, yielding a 2.55(9)
dB gain over standard, single-ensemble methods. Finally, we program a sequence
which performs local dynamical decoupling during Ramsey evolution to evolve
three ensembles with variable phase sensitivities, a key ingredient of optimal
clock interrogation. Our results demonstrate the potential of fully
programmable quantum optical clocks even without entanglement and could be
combined with metrologically useful entangled states in the future
Changes of empathy in medical college and medical school students: 1-year follow up study
BACKGROUND: This study aims to determine the correlation between medical education systems, medical college (MC) and medical school (MS), and empathy by investigating the changes in empathy among students with each additional year of medical education. METHODS: The subjects were MC and MS students who had participated in the same study the previous year. All participants completed the same self-report instruments: a questionnaire on sociodemographic characteristics, and the Korean edition of the Student Version of the Jefferson Scale of Empathy (JSE-S-K), Among 334 students, the final analysis was conducted on the data provided by 113 MC and 120 MS students, excluding 101 with incomplete data. RESULTS: The age and sex did not affect the changes in empathy. Though the JSE-S-K score of MS was significantly higher than that of MC in initial investigation, this study found no difference of empathy between MC and MS. CONCLUSION: Empathy increased significantly after one year of medical education. The difference between two education systems, MC and MS, did not affect the changes in empathy
Mind bomb 1 in the lymphopoietic niches is essential for T and marginal zone B cell development
Notch signaling regulates lineage decisions at multiple stages of lymphocyte development, and Notch activation requires the endocytosis of Notch ligands in the signal-sending cells. Four E3 ubiquitin ligases, Mind bomb (Mib) 1, Mib2, Neuralized (Neur) 1, and Neur2, regulate the Notch ligands to activate Notch signaling, but their roles in lymphocyte development have not been defined. We show that Mib1 regulates T and marginal zone B (MZB) cell development in the lymphopoietic niches. Inactivation of the Mib1 gene, but not the other E3 ligases, Mib2, Neur1, and Neur2, abrogated T and MZB cell development. Reciprocal bone marrow (BM) transplantation experiments revealed that Mib1 in the thymic and splenic niches is essential for T and MZB cell development. Interestingly, when BM cells from transgenic Notch reporter mice were transplanted into Mib1-null mice, the Notch signaling was abolished in the double-negative thymocytes. In addition, the endocytosis of Dll1 was impaired in the Mib1-null microenvironment. Moreover, the block in T cell development and the failure of Dll1 endocytosis were also observed in coculture system by Mib1 knockdown. Our study reveals that Mib1 is the essential E3 ligase in T and MZB cell development, through the regulation of Notch ligands in the thymic and splenic microenvironments
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