Multipartite Entanglement Generation and Contextuality Tests Using Nondestructive Three-Qubit Parity Measurements

We report on the realization and application of nondestructive three-qubit parity measurements on nuclear spin qubits in diamond. We use high-fidelity quantum logic to map the parity of the joint state of three nuclear spin qubits onto an electronic spin qubit that acts as an ancilla, followed by a single-shot nondestructive readout of the ancilla combined with an electron spin echo to ensure outcome-independent evolution of the nuclear spins. Through the sequential application of three such parity measurements, we demonstrate the generation of genuine multipartite entangled states out of the maximally mixed state. Furthermore, we implement a single-shot version of the Greenberger-Horne-Zeilinger experiment that can generate a quantum versus classical contradiction in each run. Finally, we test a state-independent noncontextuality inequality in eight dimensions. The techniques and insights developed are relevant for fundamental tests as well as for quantum information protocols such as quantum error correction.

Entanglement distillation between solid-state quantum network nodes

The impact of future quantum networks hinges on high-quality quantum entanglement shared between network nodes. Unavoidable imperfections necessitate a means to improve remote entanglement by local quantum operations. We realize entanglement distillation on a quantum network primitive of distant electron-nuclear two-qubit nodes. The heralded generation of two copies of a remote entangled state is demonstrated through single-photon-mediated entangling of the electrons and robust storage in the nuclear spins. After applying local two-qubit gates, single-shot measurements herald the distillation of an entangled state with increased fidelity that is available for further use. The key combination of generating, storing, and processing entangled states should enable the exploration of multiparticle entanglement on an extended quantum network.

Experimental creation of quantum Zeno subspaces by repeated multi-spin projections in diamond

Repeated observations inhibit the coherent evolution of quantum states through the quantum Zeno effect. In multi-qubit systems this effect provides opportunities to control complex quantum states. Here, we experimentally demonstrate that repeatedly projecting joint observables of multiple spins creates quantum Zeno subspaces and simultaneously suppresses the dephasing caused by a quasi-static environment. We encode up to two logical qubits in these subspaces and show that the enhancement of the dephasing time with increasing number of projections follows a scaling law that is independent of the number of spins involved. These results provide experimental insight into the interplay between frequent multi-spin measurements and slowly varying noise and pave the way for tailoring the dynamics of multi-qubit systems through repeated projections.

Repeated observations of quantum states inhibit coherent evolution through the Zeno effect, providing opportunities for controlling multi-qubit systems. Here the authors demonstrate that projecting joint observables of three spins in diamond creates quantum Zeno subspaces that suppress dephasing.

Optimized quantum sensing with a single electron spin using real-time adaptive measurements

Quantum sensors based on single solid-state spins promise a unique combination of sensitivity and spatial resolution. The key challenge in sensing is to achieve minimum estimation uncertainty within a given time and with high dynamic range. Adaptive strategies have been proposed to achieve optimal performance, but their implementation in solid-state systems has been hindered by the demanding experimental requirements. Here, we realize adaptive d.c. sensing by combining single-shot readout of an electron spin in diamond with fast feedback. By adapting the spin readout basis in real time based on previous outcomes, we demonstrate a sensitivity in Ramsey interferometry surpassing the standard measurement limit. Furthermore, we find by simulations and experiments that adaptive protocols offer a distinctive advantage over the best known non-adaptive protocols when overhead and limited estimation time are taken into account. Using an optimized adaptive protocol we achieve a magnetic field sensitivity of 6.1 ± 1.7 nT Hz(-1/2) over a wide range of 1.78 mT. These results open up a new class of experiments for solid-state sensors in which real-time knowledge of the measurement history is exploited to obtain optimal performance.

An assessment of the ship drag penalty arising from light calcareous tubeworm fouling

A test coupon coated with light calcareous tubeworm fouling was scanned, scaled and reproduced for wind-tunnel testing to determine the equivalent sand grain roughness ks. It was found that this surface had a ks = 0.325 mm, substantially less than the previously reported values for light calcareous fouling. This result was used to predict the drag on a fouled full scale ship. To achieve this, a modified method for predicting the total drag of a spatially developing turbulent boundary layer (TBL), such as that on the hull of a ship, is presented. The method numerically integrates the skin friction over the length of the boundary layer, assuming an analytical form for the mean velocity profile of the TBL. The velocity profile contains the roughness (fouling) information, such that the prediction requires only an input of ks, the free-stream velocity (ship speed), the kinematic viscosity and the length of the boundary layer (the hull length). Using the equivalent sandgrain roughness height determined from experiments, a FFG-7 Oliver Perry class frigate is predicted to experience a 23% increase in total resistance at cruise, if its hull is coated in light calcareous tubeworm fouling. A similarly fouled very large crude carrier would experience a 34% increase in total resistance at cruise.

Word structures of Granada Spanish-speaking preschoolers with typical versus protracted phonological development

BACKGROUND

Research on children's word structure development is limited. Yet, phonological intervention aims to accelerate the acquisition of both speech-sounds and word structure, such as word length, stress or shapes in CV sequences. Until normative studies and meta-analyses provide in-depth information on this topic, smaller investigations can provide initial benchmarks for clinical purposes.

AIMS

To provide preliminary reference data for word structure development in a variety of Spanish with highly restricted coda use: Granada Spanish (similar to many Hispano-American varieties). To be clinically applicable, such data would need to show differences by age, developmental typicality and word structure complexity. Thus, older typically developing (TD) children were expected to show higher accuracy than younger children and those with protracted phonological development (PPD). Complex or phonologically marked forms (e.g. multisyllabic words, clusters) were expected to be late developing.

METHODS & PROCEDURES

Participants were 59 children aged 3-5 years in Granada, Spain: 30 TD children, and 29 with PPD and no additional language impairments. Single words were digitally recorded by a native Spanish speaker using a 103-word list and transcribed by native Spanish speakers, with confirmation by a second transcriber team and acoustic analysis. The program Phon 1.5 provided quantitative data.

OUTCOMES & RESULTS

In accordance with expectations, the TD and older age groups had better-established word structures than the younger children and those with PPD. Complexity was also relevant: more structural mismatches occurred in multisyllabic words, initial unstressed syllables and clusters. Heterosyllabic consonant sequences were more accurate than syllable-initial sequences. The most common structural mismatch pattern overall was consonant deletion, with syllable deletion most common in 3-year-olds and children with PPD.

CONCLUSIONS & IMPLICATIONS

The current study provides preliminary reference data for word structure development in a Spanish variety with restricted coda use, both by age and types of word structures. Between ages 3 and 5 years, global measures (whole word match, word shape match) distinguished children with typical versus protracted phonological development. By age 4, children with typical development showed near-mastery of word structures, whereas 4- and 5-year-olds with PPD continued to show syllable deletion and cluster reduction, especially in multisyllabic words. The results underline the relevance of multisyllabic words and words with clusters in Spanish phonological assessment and the utility of word structure data for identification of protracted phonological development.

Targeting MPS1 Enhances Radiosensitization of Human Glioblastoma by Modulating DNA Repair Proteins

To ensure faithful chromosome segregation, cells use the spindle assembly checkpoint (SAC), which can be activated in aneuploid cancer cells. Targeting the components of SAC machinery required for the growth of aneuploid cells may offer a cancer cell-specific therapeutic approach. In this study, the effects of inhibiting Monopolar spindle 1, MPS1 (TTK), an essential SAC kinase, on the radiosensitization of glioblastoma (GBM) cells were analyzed. Clonogenic survival was used to determine the effects of the MPS1 inhibitor NMS-P715 on radiosensitivity in multiple model systems, including GBM cell lines, a normal astrocyte, and a normal fibroblast cell line. DNA double-strand breaks (DSB) were evaluated using γH2AX foci, and cell death was measured by mitotic catastrophe evaluation. Transcriptome analysis was performed via unbiased microarray expression profiling. Tumor xenografts grown from GBM cells were used in tumor growth delay studies. Inhibition of MPS1 activity resulted in reduced GBM cell proliferation. Furthermore, NMS-P715 enhanced the radiosensitivity of GBM cells by decreased repair of DSBs and induction of postradiation mitotic catastrophe. NMS-P715 in combination with fractionated doses of radiation significantly enhanced the tumor growth delay. Molecular profiling of MPS1-silenced GBM cells showed an altered expression of transcripts associated with DNA damage, repair, and replication, including the DNA-dependent protein kinase (PRKDC/DNAPK). Next, inhibition of MPS1 blocked two important DNA repair pathways. In conclusion, these results not only highlight a role for MPS1 kinase in DNA repair and as prognostic marker but also indicate it as a viable option in glioblastoma therapy.

IMPLICATIONS

Inhibition of MPS1 kinase in combination with radiation represents a promising new approach for glioblastoma and for other cancer therapies.

Towards quantum networks of single spins: analysis of a quantum memory with an optical interface in diamond

Single defect centers in diamond have emerged as a powerful platform for quantum optics experiments and quantum information processing tasks. Connecting spatially separated nodes via optical photons into a quantum network will enable distributed quantum computing and long-range quantum communication. Initial experiments on trapped atoms and ions as well as defects in diamond have demonstrated entanglement between two nodes over several meters. To realize multi-node networks, additional quantum bit systems that store quantum states while new entanglement links are established are highly desirable. Such memories allow for entanglement distillation, purification and quantum repeater protocols that extend the size, speed and distance of the network. However, to be effective, the memory must be robust against the entanglement generation protocol, which typically must be repeated many times. Here we evaluate the prospects of using carbon nuclear spins in diamond as quantum memories that are compatible with quantum networks based on single nitrogen vacancy (NV) defects in diamond. We present a theoretical framework to describe the dephasing of the nuclear spins under repeated generation of NV spin-photon entanglement and show that quantum states can be stored during hundreds of repetitions using typical experimental coupling parameters. This result demonstrates that nuclear spins with weak hyperfine couplings are promising quantum memories for quantum networks.

A Growing Opportunity: Community Gardens Affiliated with US Hospitals and Academic Health Centers

Background

Community gardens can reduce public health disparities through promoting physical activity and healthy eating, growing food for underserved populations, and accelerating healing from injury or disease. Despite their potential to contribute to comprehensive patient care, no prior studies have investigated the prevalence of community gardens affiliated with US healthcare institutions, and the demographic characteristics of communities served by these gardens.

Methods

In 2013, national community garden databases, scientific abstracts, and public search engines (e.g., Google Scholar) were used to identify gardens. Outcomes included the prevalence of hospital-based community gardens by US regions, and demographic characteristics (age, race/ethnicity, education, household income, and obesity rates) of communities served by gardens.

Results

There were 110 healthcare-based gardens, with 39 in the Midwest, 25 in the South, 24 in the Northeast, and 22 in the West. Compared to US population averages, communities served by healthcare-based gardens had similar demographic characteristics, but significantly lower rates of obesity (27% versus 34%, P < .001).

Conclusions

Healthcare-based gardens are located in regions that are demographically representative of the US population, and are associated with lower rates of obesity in communities they serve.

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Community gardens may offer diverse public health benefits.

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We identified 110 gardens that are operating in partnership with hospitals.

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Communities served by hospital gardens may have lower obesity than US average.

Quantum information. Unconditional quantum teleportation between distant solid-state quantum bits

Realizing robust quantum information transfer between long-lived qubit registers is a key challenge for quantum information science and technology. Here we demonstrate unconditional teleportation of arbitrary quantum states between diamond spin qubits separated by 3 meters. We prepare the teleporter through photon-mediated heralded entanglement between two distant electron spins and subsequently encode the source qubit in a single nuclear spin. By realizing a fully deterministic Bell-state measurement combined with real-time feed-forward, quantum teleportation is achieved upon each attempt with an average state fidelity exceeding the classical limit. These results establish diamond spin qubits as a prime candidate for the realization of quantum networks for quantum communication and network-based quantum computing.

Universal control and error correction in multi-qubit spin registers in diamond

Quantum registers of nuclear spins coupled to electron spins of individual solid-state defects are a promising platform for quantum information processing. Pioneering experiments selected defects with favourably located nuclear spins with particularly strong hyperfine couplings. To progress towards large-scale applications, larger and deterministically available nuclear registers are highly desirable. Here, we realize universal control over multi-qubit spin registers by harnessing abundant weakly coupled nuclear spins. We use the electron spin of a nitrogen-vacancy centre in diamond to selectively initialize, control and read out carbon-13 spins in the surrounding spin bath and construct high-fidelity single- and two-qubit gates. We exploit these new capabilities to implement a three-qubit quantum-error-correction protocol and demonstrate the robustness of the encoded state against applied errors. These results transform weakly coupled nuclear spins from a source of decoherence into a reliable resource, paving the way towards extended quantum networks and surface-code quantum computing based on multi-qubit nodes.

Abstract 1584: Targeting the mitotic checkpoint with inhibition of MPS1 kinase enhances radiosensitivity of glioblastoma cancer cells

During the cell cycle, genomic stability requires accurate chromosome segregation. Errors in this process can cause aneuploidy and lead to tumorigenesis. To ensure faithful chromosome segregation, cells develop a mechanism called the spindle assembly checkpoint (SAC). Cancer cells are addicted to the components of SAC machinery for a faithful entry of the cell into anaphase. Thus, targeting the molecular mechanisms required for the growth of aneuploid cells may be a more cancer cell specific therapeutic approach applicable to broader tumor histologies. Previously, using a siRNA based RNAi screen we identified MPS1 kinase, (also known as TTK) as an important kinase for GBM cell survival. MPS1 is an essential SAC enzyme aberrantly overexpressed in a wide range of tumors and necessary for tumor cell proliferation.

We observed inhibition of GBM cell growth when MPS1 was downregulated by number of MPS1 specific siRNAs. This was further validated using a selective and orally bioavailable MPS1 inhibitor NMS-P715 in various in-vitro cell assays. The inhibition of cell death was induced partly by apoptosis; however, the major mechanism was mitotic catastrophe. Cells treated with NMS-P715 showed an increase in cells in G2-M phase of cell cycle compared to control cells followed by mitotic catastrophe. Moreover, inhibition of MPS1 resulted in radiosensitization of GBM cells. We observed decrease in DNA damage repair and significant retention of γH2AX foci after combination of radiation (RT) with NMS-P715 compared to individual treatments. Next, radiation in combination with NMS-P715 inhibited cell survival ability of GBM cells in a colony formation assay. Further, NMS-P715 could inhibit GBM tumor growth in an orthotopic brain tumor model. Finally, in order to determine MPS1 associated molecular pathways, we compared gene expression profile in MPS1 knockdown cells compared to the control by microarray analysis. Ingenuity pathway and Gene Set Enrichment Analysis were used to investigate the biological relevance of the MPS1 modulated genes. We identified genes important in cell assembly, cell organization, DNA repair and cell death pathways. Thus, inhibiting MPS1 kinase in combination with radiation could represent a promising new approach to GBM therapy.

Citation Format: Anita T. Tandle, Ryan Hanson, Uday B. Maachani, Tamalee Meushaw, Shuping Zhao, Uma Shankavaram, Philip Tofilon, Natasha J. Caplen, Kevin Camphausen. Targeting the mitotic checkpoint with inhibition of MPS1 kinase enhances radiosensitivity of glioblastoma cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1584. doi:10.1158/1538-7445.AM2013-1584

Probing dynamics of an electron-spin ensemble via a superconducting resonator

We study spin relaxation and diffusion in an electron-spin ensemble of nitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing magnetic field (80-300 mT). Measurements exploit field-controlled coupling of the ensemble to two modes of a transmission-line resonator. The observed temperature-independent spin relaxation time indicates that spin outdiffusion across the mode volume dominates over spin-lattice relaxation. Depolarization of one hyperfine-split subensemble by pumping of another indicates fast cross relaxation, with implications for the use of subensembles as independent quantum memories.

Detection and control of individual nuclear spins using a weakly coupled electron spin

We experimentally isolate, characterize, and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multipulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond.

A phase 2 study of pegylated interferon α-2b (PEG-Intron(®)) in children with diffuse intrinsic pontine glioma

BACKGROUND

Interferon-α is a cytokine that has demonstrated activity in patients with supratentorial gliomas, but its ideal dose and schedule of administration is unknown. Studies suggest that low-dose, continuous exposure is more efficacious than intermittent, high doses. The authors performed a phase 2 study of recombinant interferon α-2b with monomethoxy polyethylene glycol (PEG-Intron(®)) in children with diffuse intrinsic pontine glioma (DIPG), a population with dismal survival despite decades of clinical investigation. The primary objective was to compare 2-year survival with a historic cohort that received radiation therapy alone.

METHODS

Patients received weekly subcutaneous PEG-Intron(®) at a dose of 0.3 μg/kg beginning 2 to 10 weeks after the completion of radiation therapy until they developed disease progression. Patients were evaluated clinically and radiographically at regular intervals. Serum and urine were assayed for biomarkers before each cycle. Quality-of-life (QOL) evaluations were administered at baseline and before every other cycle of therapy to the parents of patients ages 6 to 18 years.

RESULTS

Thirty-two patients (median age, 5.3 years; range, 1.8-14.8 years) were enrolled and received a median of 7 cycles of therapy (range, from 1 cycle to ≥70 cycles). PEG-Intron(®) was well tolerated, and no decrease in QOL scores was noted in the subset of patients tested. The 2-year survival rate was 14%, which was not significantly improved compared with the historic cohort. However, the median time to progression was 7.8 months, which compared favorably with recent trials reporting a time to progression of 5 months in a similar population.

CONCLUSIONS

Although low-dose PEG-Intron(®) therapy did not significantly improve 2-year survival in children with DIPG compared with an historic control population, it did delay the time to progression.