Dynamics of a qubit while simultaneously monitoring its relaxation and dephasing

Decoherence originates from the leakage of quantum information into external degrees of freedom. For a qubit the two main decoherence channels are relaxation and dephasing. Here, we report an experiment on a superconducting qubit where we retrieve part of the lost information in both of these channels. We demonstrate that raw averaging the corresponding measurement records provides a full quantum tomography of the qubit state where all three components of the effective spin-1/2 are simultaneously measured. From single realizations of the experiment, it is possible to infer the quantum trajectories followed by the qubit state conditioned on relaxation and/or dephasing channels. The incompatibility between these quantum measurements of the qubit leads to observable consequences in the statistics of quantum states. The high level of controllability of superconducting circuits enables us to explore many regimes from the Zeno effect to underdamped Rabi oscillations depending on the relative strengths of driving, dephasing and relaxation.Comment: Supplemental videos can be found at http://physinfo.fr/publications/Ficheux1710.html and supplemental information can be found as an ancillary file on arxi

Conditional symmetries and Riemann invariants for inhomogeneous hydrodynamic-type systems

A new approach to the solution of quasilinear nonelliptic first-order systems of inhomogeneous PDEs in many dimensions is presented. It is based on a version of the conditional symmetry and Riemann invariant methods. We discuss in detail the necessary and sufficient conditions for the existence of rank-2 and rank-3 solutions expressible in terms of Riemann invariants. We perform the analysis using the Cayley-Hamilton theorem for a certain algebraic system associated with the initial system. The problem of finding such solutions has been reduced to expanding a set of trace conditions on wave vectors and their profiles which are expressible in terms of Riemann invariants. A couple of theorems useful for the construction of such solutions are given. These theoretical considerations are illustrated by the example of inhomogeneous equations of fluid dynamics which describe motion of an ideal fluid subjected to gravitational and Coriolis forces. Several new rank-2 solutions are obtained. Some physical interpretation of these results is given.Comment: 19 page

Identification of Mycobacterium tuberculosis clinical isolates in Bangladesh by a species distinguishable multiplex PCR

<p>Abstract</p> <p>Background</p> <p>Species identification of isolates belonging to the <it>Mycobacterium tuberculosis </it>complex (MTC) seems to be important for the appropriate treatment of patients, since <it>M. bovis </it>is naturally resistant to a first line anti-tuberculosis (TB) drug, pyrazinamide, while most of the other MTC members are susceptible to this antimicrobial agent. A simple and low-cost differentiation method was needed in higher TB burden countries, such as Bangladesh, where the prevalence of <it>M. bovis </it>among people or cattle has not been investigated.</p> <p>Methods</p> <p>Genetic regions <it>cfp32</it>, RD9 and RD12 were chosen as targets for a species distinguishable multiplex PCR and the system was evaluated with twenty reference strains of mycobacterial species including non-tubercular mycobacteria (NTM). A total of 350 clinical MTC isolates obtained in Bangladesh were then analyzed with this multiplex PCR.</p> <p>Results</p> <p>All of the MTC reference strains gave expected banding patterns and no non-specific amplifications were observed in the NTM strains. Out of 350 clinical isolates examined by this method, 347 (99.1%) were positive for all of the <it>cfp32</it>, RD9 and RD12 and determined as <it>M. tuberculosis</it>. Two isolates lacked <it>cfp32 </it>PCR product and one lacked RD12, however, those three samples were further examined and identified as <it>M. tuberculosis </it>by the sequence analyses of <it>hsp65 </it>and <it>gyrB</it>.</p> <p>Conclusions</p> <p>The MTC-discrimination multiplex PCR (MTCD-MPCR) developed in this study showed high specificity and was thought to be very useful as a routine test because of its simplicity. In the current survey, all the 350 MTC isolates obtained from Bangladesh TB patients were determined as <it>M. tuberculosis </it>and no other MTC were detected. This result suggested the general TB treatment regimen including pyrazinamide to be the first choice in Bangladesh.</p

Goos-H\"{a}nchen-like shifts for Dirac fermions in monolayer graphene barrier

We investigate the Goos-H\"{a}nchen-like shifts for Dirac fermions in transmission through a monolayer graphene barrier. The lateral shifts, as the functions of the barrier's width and the incidence angle, can be negative and positive in Klein tunneling and classical motion, respectively. Due to their relations to the transmission gap, the lateral shifts can be enhanced by the transmission resonances when the incidence angle is less than the critical angle for total reflection, while their magnitudes become only the order of Fermi wavelength when the incidence angle is larger than the critical angle. These tunable beam shifts can also be modulated by the height of potential barrier and the induced gap, which gives rise to the applications in graphene-based devices.Comment: 5 pages, 5 figure

Two-stage therapeutic utility of ectopically formed bone tissue in skeletal muscle induced by adeno-associated virus containing bone morphogenetic protein-4 gene

Background: The major disadvantage of using a stem cell-based bone morphogenetic protein-4 (BMP4) gene therapy for skull defect is the overgrowth of generated bone tissue in situ. In the present study, to overcome bony overgrowth of stem cell based-gene therapy, a new strategy of two-stage bone tissue engineering by an adeno-associated virus containing BMP4 gene (AAV-BMP4) gene therapy was used. Methods: AAV-BMP4 was purposely implanted in the skeletal muscle of mice to generate ectopic bone tissues during the first stage. Next, the newly formed ectopic bone tissues were harvested and then transplanted to repair the mouse skull defect during the second stage. Results: The results showed that skeletal muscle implantation of AAV-BMP4 yielded a large amount of new bone tissues. The ectopic bone tissues can be harvested as a bone graft and can successfully repair the mouse skull defect without any bony overgrowth in situ. Conclusion: The results indicate that the bone tissues purposely generated by AAV-BMP4 in the skeletal muscle may be a new alternative of bone grafting for clinical purposes

G-quadruplex formation at the 3′ end of telomere DNA inhibits its extension by telomerase, polymerase and unwinding by helicase

Telomere G-quadruplex is emerging as a promising anti-cancer target due to its inhibition to telomerase, an enzyme expressed in more than 85% tumors. Telomerase-mediated telomere extension and some other reactions require a free 3′ telomere end in single-stranded form. G-quadruplex formation near the 3′ end of telomere DNA can leave a 3′ single-stranded tail of various sizes. How these terminal structures affect reactions at telomere end is not clear. In this work, we studied the 3′ tail size-dependence of telomere extension by either telomerase or the alternative lengthening of telomere (ALT) mechanism as well as telomere G-quadruplex unwinding. We show that these reactions require a minimal tail of 8, 12 and 6 nt, respectively. Since we have shown that G-quadruplex tends to form at the farthest 3′ distal end of telomere DNA leaving a tail of no more than 5 nt, these results imply that G-quadruplex formation may play a role in regulating reactions at the telomere ends and, as a result, serve as effective drug target for intervening telomere function

Lineage specific composition of cyclin D–CDK4/CDK6–p27 complexes reveals distinct functions of CDK4, CDK6 and individual D-type cyclins in differentiating cells of embryonic origin

Objectives: This article is to study the role of G1/S regulators in differentiation of pluripotent embryonic cells. Materials and methods: We established a P19 embryonal carcinoma cell-based experimental system, which profits from two similar differentiation protocols producing endodermal or neuroectodermal lineages. The levels, mutual interactions, activities, and localization of G1/S regulators were analysed with respect to growth and differentiation parameters of the cells. Results and Conclusions: We demonstrate that proliferation parameters of differentiating cells correlate with the activity and structure of cyclin A/E–CDK2 but not of cyclin D–CDK4/6–p27 complexes. In an exponentially growing P19 cell population, the cyclin D1–CDK4 complex is detected, which is replaced by cyclin D2/3–CDK4/6–p27 complex following density arrest. During endodermal differentiation kinase-inactive cyclin D2/D3–CDK4–p27 complexes are formed. Neural differentiation specifically induces cyclin D1 at the expense of cyclin D3 and results in predominant formation of cyclin D1/D2–CDK4–p27 complexes. Differentiation is accompanied by cytoplasmic accumulation of cyclin Ds and CDK4/6, which in neural cells are associated with neural outgrowths. Most phenomena found here can be reproduced in mouse embryonic stem cells. In summary, our data demonstrate (i) that individual cyclin D isoforms are utilized in cells lineage specifically, (ii) that fundamental difference in the function of CDK4 and CDK6 exists, and (iii) that cyclin D–CDK4/6 complexes function in the cytoplasm of differentiated cells. Our study unravels another level of complexity in G1/S transition-regulating machinery in early embryonic cells

Study of CP violation in Dalitz-plot analyses of B0 --> K+K-KS, B+ --> K+K-K+, and B+ --> KSKSK+

We perform amplitude analyses of the decays $B^0 \to K^+K^-K^0_S$, $B^+ \rightarrow K^+K^-K^+$, and $B^+ \to K^0_S K^0_S K^+$, and measure CP-violating parameters and partial branching fractions. The results are based on a data sample of approximately $470\times 10^6$ $B\bar{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory. For $B^+ \to K^+K^-K^+$, we find a direct CP asymmetry in $B^+ \to \phi(1020)K^+$ of $A_{CP}= (12.8\pm 4.4 \pm 1.3)$, which differs from zero by $2.8 \sigma$. For $B^0 \to K^+K^-K^0_S$, we measure the CP-violating phase $\beta_{\rm eff} (\phi(1020)K^0_S) = (21\pm 6 \pm 2)^\circ$. For $B^+ \to K^0_S K^0_S K^+$, we measure an overall direct CP asymmetry of $A_{CP} = (4 ^{+4}_{-5} \pm 2)$. We also perform an angular-moment analysis of the three channels, and determine that the $f_X(1500)$ state can be described well by the sum of the resonances $f_0(1500)$, $f_2^{\prime}(1525)$, and $f_0(1710)$.Comment: 35 pages, 68 postscript figures. v3 - minor modifications to agree with published versio