138 research outputs found
Experimental investigation of pulsed entangled photons and photonic quantum channels
The development of key devices and systems in quantum information technology,
such as entangled particle sources, quantum gates and quantum cryptographic
systems, requires a reliable and well-established method for characterizing how
well the devices or systems work. We report our recent work on experimental
characterization of pulsed entangled photonic states and photonic quantum
channels, using the methods of state and process tomography. By using state
tomography, we could reliably evaluate the states generated from a two-photon
source under development and develop a highly entangled pulsed photon source.
We are also devoted to characterization of single-qubit and two-qubit photonic
quantum channels. Characterization of typical single-qubit decoherence channels
has been demonstrated using process tomography. Characterization of two-qubit
channels, such as classically correlated channels and quantum mechanically
correlated channels is under investigation. These characterization techniques
for quantum states and quantum processes will be useful for developing photonic
quantum devices and for improving their performances.Comment: 12 pages, 8 figures, in Quantum Optics in Computing and
Communications, Songhao Liu, Guangcan Guo, Hoi-Kwong Lo, Nobuyuki Imoto,
Eds., Proceedings of SPIE Vol. 4917, pp.13-24 (2002
Hypothesis testing for an entangled state produced by spontaneous parametric down conversion
Generation and characterization of entanglement are crucial tasks in quantum
information processing. A hypothesis testing scheme for entanglement has been
formulated. Three designs were proposed to test the entangled photon states
created by the spontaneous parametric down conversion. The time allocations
between the measurement vectors were designed to consider the anisotropic
deviation of the generated photon states from the maximally entangled states.
The designs were evaluated in terms of the p-value based on the observed data.
It has been experimentally demonstrated that the optimal time allocation
between the coincidence and anti-coincidence measurement vectors improves the
entanglement test. A further improvement is also experimentally demonstrated by
optimizing the time allocation between the anti-coincidence vectors. Analysis
on the data obtained in the experiment verified the advantage of the
entanglement test designed by the optimal time allocation.Comment: 7 figures, 9 pages. This paper is revised for increasing the
readership for experimentalists. Hence, the mathematical part is moved to a
new manuscript quant-ph/060802
Statistical analysis on testing of an entangled state based on Poisson distribution framework
A hypothesis testing scheme for entanglement has been formulated based on the
Poisson distribution framework instead of the POVM framework. Three designs
were proposed to test the entangled states in this framework. The designs were
evaluated in terms of the asymptotic variance. It has been shown that the
optimal time allocation between the coincidence and anti-coincidence
measurement bases improves the conventional testing method. The test can be
further improved by optimizing the time allocation between the anti-coincidence
bases.Comment: This paper is an extended version of the theoretical part of v1 of
quant-ph/0603254.quant-ph/0603254 is revised so that it is more familiar to
experimentalist
Detecting the inseparability and distillability of continuous variable states in Fock space
The partial transposition(PT) operation is an effecient tool in detecting the
inseparability of a mixed state. We give an explicit formula for the PT
operation for the continuous variable states in Fock space. We then give the
necessary and sufficient condition for the positivity of Gaussian operators.
Based on this, a number of creterions on the inseparability and distillability
for the multimode Gaussian states are naturally drawn. We finally give an
explicit formula for the state in a subspace of a global Gaussian state. This
formula, together with the known results for Gaussian states, gives the
criterions for the inseparability and distillability in a subspace of the
global Gaussian state.Comment: 8 pages, no figure, some typing errors correcte
Epithelial EP4 plays an essential role in maintaining homeostasis in colon
Colonic epithelial cells comprise the mucosal barrier, and their dysfunction promotes microbial invasion from the gut lumen and induces the development of intestinal inflammation. The EP4 receptor is known to mediate the protective effect of prostaglandin (PG) E2 in the gastrointestinal tract; however, the exact role of epithelial EP4 in intestinal pathophysiology remains unknown. In the present study, we aimed to investigate the role of epithelial EP4 in maintaining colonic homeostasis by characterizing the intestinal epithelial cell-specific EP4 knockout (EP4 cKO) mice. Mice harboring the epithelial EP4 deletion showed significantly lower colonic crypt depth and lower numbers of secretory cell lineages, as well as impaired epithelial cells in the colon. Interestingly, EP4-deficient colon epithelia showed a higher number of apoptotic cells. Consistent with the defect in mucosal barrier function of colonic epithelia and secretory cell lineages, EP4 cKO colon stroma showed enhanced immune cell infiltration, which was accompanied by increased production of inflammatory cytokines. Furthermore, EP4-deficient colons were susceptible to dextran sulfate sodium (DSS)-induced colitis. Our study is the first to demonstrate that epithelial EP4 loss resulted in potential "inflammatory" status under physiological conditions. These findings provided insights into the crucial role of epithelial PGE2/EP4 axis in maintaining intestinal homeostasis
Magnetization process for a quasi-one-dimensional S=1 antiferromagnet
We investigate the magnetization process for a quasi-one-dimensional S=1
antiferromagnet with bond alternation. By combining the density matrix
renormalization group method with the interchain mean-field theory, we discuss
how the interchain coupling affects the magnetization curve. It is found that
the width of the magnetization plateau is considerably reduced upon introducing
the interchain coupling. We obtain the phase diagram in a magnetic field. The
effect of single-ion anisotropy is also addressed.Comment: 6 pages, 7 eps figure
Context-Dependent Roles of Hes1 in the Adult Pancreas and Pancreatic Tumor Formation
[Background & Aims] The Notch signaling pathway is an important pathway in the adult pancreas and in pancreatic ductal adenocarcinoma (PDAC), with hairy and enhancer of split-1 (HES1) as the core molecule in this pathway. However, the roles of HES1 in the adult pancreas and PDAC formation remain controversial. [Methods] We used genetically engineered dual-recombinase mouse models for inducing Hes1 deletion under various conditions. [Results] The loss of Hes1 expression in the adult pancreas did not induce phenotypic alterations. However, regeneration was impaired after caerulein-induced acute pancreatitis. In a pancreatic intraepithelial neoplasia (PanIN) mouse model, PanINs rarely formed when Hes1 deletion preceded PanIN formation, whereas more PanINs were formed when Hes1 deletion succeeded PanIN formation. In a PDAC mouse model, PDAC formation was also enhanced by Hes1 deletion after PanIN/PDAC development; therefore, Hes1 promotes PanIN initiation but inhibits PanIN/PDAC progression. RNA sequencing and chromatin immunoprecipitation-quantitative polymerase chain reaction revealed that Hes1 deletion enhanced epithelial-to-mesenchymal transition via Muc5ac up-regulation in PDAC progression. The results indicated that HES1 is not required for maintaining the adult pancreas under normal conditions, but is important for regeneration during recovery from pancreatitis; moreover, Hes1 plays different roles, depending on the tumor condition. [Conclusions] Our findings highlight the context-dependent roles of HES1 in the adult pancreas and pancreatic cancer
Impact of neoadjuvant intensity-modulated radiation therapy on borderline resectable pancreatic cancer with arterial abutment; a prospective, open-label, phase II study in a single institution
BACKGROUND: Borderline resectable pancreatic cancer (BRPC) is a category of pancreatic cancer that is anatomically widely spread, and curative resection is uncommon with upfront surgery. Intensity-modulated radiation therapy (IMRT) is a form of radiation therapy that delivers precise radiation to a tumor while minimizing the dose to surrounding normal tissues. Here, we conducted a phase 2 study to estimate the curability and efficacy of neoadjuvant chemoradiotherapy using IMRT (NACIMRT) for patients with BRPC with arterial abutment (BRPC-A). METHODS: A total of 49 BRPC-A patients were enrolled in this study and were treated at our hospital according to the study protocol between June 2013 and March 2021. The primary endpoint was microscopically margin-negative resection (R0) rates and we subsequently analyzed safety, histological effect of the treatment as well as survivals among patients with NACIMRT. RESULTS: Twenty-nine patients (59.2%) received pancreatectomy after NACIMRT. The R0 rate in resection patients was 93.1% and that in the whole cohort was 55.1%. No mortality was encountered. Local therapeutic effects as assessed by Evans classification showed good therapeutic effect (Grade 1, 3.4%; Grade 2a, 31.0%; Grade 2b, 48.3%; Grade 3, 3.4%; Grade 4, 3.4%). Median disease-free survival was 15.5 months. Median overall survival in the whole cohort was 35.1 months. The only independent prognostic pre-NACIMRT factor identified was serum carbohydrate antigen 19-9 (CA19-9) > 400 U/ml before NACIMRT. CONCLUSIONS: NACIMRT showed preferable outcome without significant operative morbidity for BRPC-A patients. NACIMRT contributes to good local tumor control, but a high initial serum CA19-9 implies poor prognosis even after neoadjuvant treatment. TRIAL REGISTRATION: UMIN-CTR Clinical Trial: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000011776 Registration number: UMIN000010113. Date of first registration: 01/03/2013
- …