416 research outputs found

    On Integrable Backgrounds Self-dual under Fermionic T-duality

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    We study the fermionic T-duality symmetry of integrable Green-Schwarz sigma-models on AdS backgrounds with Ramond-Ramond fluxes in various dimensions. We show that sigma-models based on supercosets of PSU supergroups, such as AdS_2 \times S^2 and AdS_3 \times S^3 are self-dual under fermionic T-duality, while supercosets of OSp supergroups such as non-critical AdS_2 and AdS_4 models, and the critical AdS_4 \times CP^3 background are not. We present a general algebraic argument to when a supercoset is expected to have a fermionic T-duality symmetry, and when it will fail to have one.Comment: LaTeX, 27 pages, no figures, JHEP3 style; v2: references added; v3: a comment in subsection 3.3 and a reference added; v4: fixed typos, published versio

    On the fermionic T-duality of the AdS_4 \times CP^3 sigma-model

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    In this note we consider a fermionic T-duality of the coset realization of the type IIA sigma-model on AdS_4 \times CP^3 with respect to the three flat directions in AdS_4, six of the fermionic coordinates and three of the CP^3 directions. We show that the Buscher procedure fails as it leads to a singular transformation and discuss the result and its implications.Comment: LaTeX2e, 9 pages, no figures, JHEP style; v2: minor clarifications; v3: typos fixed, matches the published versio

    Successful pregnancy following transfer of frozen-thawed embryos in a patient with pseudomyxoma peritonei who underwent peritonectomy and bilateral oophorectomy

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    Pseudomyxoma peritonei is a rare, chronic relapsing disease in which tumor cells in the abdomen produce excessive mucin with a significant mortality rate. We describe a young unmarried nulligrava who underwent fertility preservation by in vitro fertilisation and embryo cryopreservation prior to radical surgery and adjuvant chemotherapy. Pregnancy was achieved, although complicated by obstructive uropathy. She delivered a healthy infant at 32 weeks' gestation. The few descriptions of fertility and pregnancy outcome in pseudomyxoma peritonei that appear in the literature are reviewed

    Integrability of Type II Superstrings on Ramond-Ramond Backgrounds in Various Dimensions

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    We consider type II superstrings on AdS backgrounds with Ramond-Ramond flux in various dimensions. We realize the backgrounds as supercosets and analyze explicitly two classes of models: non-critical superstrings on AdS_{2d} and critical superstrings on AdS_p\times S^p\times CY. We work both in the Green--Schwarz and in the pure spinor formalisms. We construct a one-parameter family of flat currents (a Lax connection) leading to an infinite number of conserved non-local charges, which imply the classical integrability of both sigma-models. In the pure spinor formulation, we use the BRST symmetry to prove the quantum integrability of the sigma-model. We discuss how classical \kappa-symmetry implies one-loop conformal invariance. We consider the addition of space-filling D-branes to the pure spinor formalism.Comment: LaTeX2e, 56 pages, 1 figure, JHEP style; v2: references added, typos fixed in some equations; v3: typos fixed to match the published versio

    Semiconductor-based DNA sequencing of histone modification states

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    The recent development of a semiconductor-based, non-optical DNA sequencing technology promises scalable, low-cost and rapid sequence data production. The technology has previously been applied mainly to genomic sequencing and targeted re-sequencing. Here we demonstrate the utility of Ion Torrent semiconductor-based sequencing for sensitive, efficient and rapid chromatin immunoprecipitation followed by sequencing (ChIP-seq) through the application of sample preparation methods that are optimized for ChIP-seq on the Ion Torrent platform. We leverage this method for epigenetic profiling of tumour tissues

    Coherent manipulation of nuclear spins in the strong driving regime

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    Spin-based quantum information processing makes extensive use of spin-state manipulation. This ranges from dynamical decoupling of nuclear spins in quantum sensing experiments to applying logical gates on qubits in a quantum processor. Fast manipulation of spin states is highly desirable for accelerating experiments, enhancing sensitivity, and applying elaborate pulse sequences. Strong driving using intense radio-frequency (RF) fields can, therefore, facilitate fast manipulation and enable broadband excitation of spin species. In this work, we present an antenna for strong driving in quantum sensing experiments and theoretically address challenges of the strong driving regime. First, we designed and implemented a micron-scale planar spiral RF antenna capable of delivering intense fields to a sample. The planar antenna is tailored for quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center and should be applicable to other solid-state defects. The antenna has a broad bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for cryogenic and ultrahigh vacuum conditions. We measure the magnetic field induced by the antenna and estimate a field-to-current ratio of 113 +/- 16 G/A, representing a six-fold increase in efficiency compared to the state-of-the-art, crucial for cryogenic experiments. We demonstrate the antenna by driving Rabi oscillations in 1H spins of an organic sample on the diamond surface and measure 1H Rabi frequencies of over 500 kHz, i.e. pi -pulses shorter than 1 mu s -an order of magnitude faster than previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we discuss the implications of driving spins with a field tilted from the transverse plane in a regime where the driving amplitude is comparable to the spin-state splitting, such that the rotating wave approximation does not describe the dynamics well. We present a simple recipe to optimize pulse fidelity in this regime based on a phase and offset-shifted sine drive, which may be optimized in situ without numerical optimization procedures or precise modeling of the experiment. We consider this approach in a range of driving amplitudes and show that it is particularly efficient in the case of a tilted driving field. The results presented here constitute a foundation for implementing fast nuclear spin control in various systems

    Coherent manipulation of nuclear spins in the strong driving regime

    Full text link
    Spin-based quantum information processing makes extensive use of spin-state manipulation. This ranges from dynamical decoupling of nuclear spins in quantum sensing experiments to applying logical gates on qubits in a quantum processor. Here we present an antenna for strong driving in quantum sensing experiments and theoretically address challenges of the strong driving regime. First, we designed and implemented a micron-scale planar spiral RF antenna capable of delivering intense fields to a sample. The planar antenna is tailored for quantum sensing experiments using the diamond's nitrogen-vacancy (NV) center and should be applicable to other solid-state defects. The antenna has a broad bandwidth of 22 MHz, is compatible with scanning probes, and is suitable for cryogenic and ultrahigh vacuum conditions. We measure the magnetic field induced by the antenna and estimate a field-to-current ratio of 113±16113\pm 16 G/A, representing a x6 increase in efficiency compared to the state-of-the-art. We demonstrate the antenna by driving Rabi oscillations in 1^1H spins of an organic sample on the diamond surface and measure 1^1H Rabi frequencies of over 500 kHz, i.e., π\mathrm{\pi}-pulses shorter than 1 μs\mu s - faster than previously reported in NV-based nuclear magnetic resonance (NMR). Finally, we discuss the implications of driving spins with a field tilted from the transverse plane in a regime where the driving amplitude is comparable to the spin-state splitting, such that the rotating wave approximation does not describe the dynamics well. We present a recipe to optimize pulse fidelity in this regime based on a phase and offset-shifted sine drive, that may be optimized without numerical optimization procedures or precise modeling of the experiment. We consider this approach in a range of driving amplitudes and show that it is particularly efficient in the case of a tilted driving field
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