Parity detection and entanglement with a Mach-Zehnder interferometer

A parity meter projects the state of two qubits onto two subspaces with different parities, the states in each parity class being indistinguishable. It has application in quantum information for its entanglement properties. In our work we consider the electronic Mach-Zehnder interferometer (MZI) coupled capacitively to two double quantum dots (DQDs), one on each arm of the MZI. These charge qubits couple linearly to the charge in the arms of the MZI. A key advantage of an MZI is that the qubits are well separated in distance so that mutual interaction between them is avoided. Assuming equal coupling between both DQDs and the arms and the same bias for each DQD, this setup usually detects three different currents, one for the odd states and two for each even state. Controlling the magnetic flux of the MZI, we can operate the MZI as a parity meter: only two currents are measured at the output, one for each parity class. In this configuration, the MZI acts as an ideal detector, its Heisenberg efficiency being maximal. For a class of initial states, the initially unentangled DQDs become entangled through the parity measurement process with probability one.Comment: 9 pages, 2 figure

Quantum plasmonics: second-order coherence of surface plasmons launched by quantum emitters into a metallic film

We address the issue of the second-order coherence of single surface plasmons launched by a quantum source of light into extended gold films. The quantum source of light is made of a scanning fluorescent nanodiamond hosting five nitrogen-vacancy (NV) color centers. By using a specially designed microscopy that combines near-field optics with far-field leakage-radiation microscopy in the Fourier space and adapted spatial filtering, we find that the quantum statistics of the initial source of light is preserved after conversion to surface plasmons and propagation along the polycrystalline gold film.Comment: Second version with minor changes made to comply with Referees' comments. Editorially approved for publication in Phys. Rev. B on 22 June 201

Development of a novel polyamide-based agent to inhibit EVI1 function

The EVI1 gene at chromosome 3q26 is associated with acute myeloid leukemogenesis, due to both chromosomal rearrangement and to overexpression in the absence of rearrangement. Some rearrangements such as t(3;3) and inv(3) result in overexpression of EVI1 protein, while translocation t(3;21) yields an AML1-MDS1-EVI1 (AME) fusion protein. EVI1 possesses two zinc finger domains, an N-terminal domain with fingers 1–7, which binds to GACAAGATA, and a C-terminal domain (fingers 8–10) which binds GAAGATGAG. Inhibition of EVI1 function with a small molecule compound may provide a targeted therapy for EVI1-expressing leukemias. As a first step towards inhibiting the leukemogenic function of EVI1, we performed structure-function studies on both EVI1 and AME protein to determine what domains are critical for malignant transformation activity. Assays were Rat1 fibroblasts in a soft agar colony forming assay for EVI1; primary bone marrow cells in a serial replating assay for AME. Both assays revealed that mutation of arginine 205 in zinc finger 6 of EVI1, which completely abrogates sequencespecific DNA binding via the N-terminal zinc finger domain, resulted in complete loss of transforming activity; mutations in other domains, such as the C-terminal zinc finger domain, CtBP binding domain, and the domains of AML1 had less of an effect or no effect on transforming activity. In an effort to inhibit EVI1 leukemogenic function, we developed a polyamide, DH-IV-298, designed to block zinc fingers 1–7 binding to the GACAAGATA motif. DNAseI footprinting revealed a specific interaction between DH-IV-298 and the GACAAGATA motif; no significant interaction was observed elsewhere; a mismatch polyamide failed to footprint at equivalent concentrations; and DH-IV-298 failed to bind to a control DNA lacking the GACAAGATA motif. Electromobility shift assay showed that, at a 1:1 polyamide:DNA ratio, DH-IV-298 lowered EVI1:DNA affinity by over 98%, while mismatch was significantly less effective (74% reduction). To assess the effect of DH-IV-298 on EVI1 binding to DNA in vivo, we performed CAT reporter assays in a NIH-3T3-derived cell line with a chromosome-embedded tet-inducible EVI1-VP16 as well as a EVI1-responsive CAT reporter. Removal of tetracycline resulted in a four-fold increase in CAT activity that was completely blocked by DH-IV-298. The mismatch polyamide was significantly less effective than DH-IV-298. Further studies are being performed to assess the effect on endogenous gene expression, and on growth of leukemic cells that express EVI1. These studies provide evidence that a cell permeable small molecule compound may effectively block the activity of a leukemogenic transcription factor

General Properties of the Gravitational Wave Spectrum from Phase Transitions

In this paper we discuss some general aspects of the gravitational wave background arising from post-inflationary short-lasting cosmological events such as phase transitions. We concentrate on the physics which determines the shape and the peak frequency of the gravitational wave spectrum. We then apply our general findings to the case of bubble collisions during a first order phase transition and compare different results in the recent literature.Comment: 11 pages, 8 figures; v2: minor clarifications, published versio

Electron Waiting Times in Mesoscopic Conductors

Electron transport in mesoscopic conductors has traditionally involved investigations of the mean current and the fluctuations of the current. A complementary view on charge transport is provided by the distribution of waiting times between charge carriers, but a proper theoretical framework for coherent electronic systems has so far been lacking. Here we develop a quantum theory of electron waiting times in mesoscopic conductors expressed by a compact determinant formula. We illustrate our methodology by calculating the waiting time distribution for a quantum point contact and find a cross-over from Wigner-Dyson statistics at full transmission to Poisson statistics close to pinch-off. Even when the low-frequency transport is noiseless, the electrons are not equally spaced in time due to their inherent wave nature. We discuss the implications for renewal theory in mesoscopic systems and point out several analogies with energy level statistics and random matrix theory.Comment: 4+ pages, 3 figure

Two hundred years of land-use change in the South Swedish Uplands : comparison of historical map-based estimates with a pollen-based reconstruction using the landscape reconstruction algorithm

International audienceLong-term records of environmental history at decadal to millennial timescales enable an assessment of ecosystem variability and responses to past anthropogenic disturbances and are fundamental for the development of environmental management strategies. This study examines the local variability of land-use history in the South Swedish Uplands over the last 200 years based on pollen records from three lake-sediment successions. Temporal changes in the proportional cover of 14 plant taxa were quantified as percentages using the landscape reconstruction algorithm (LRA). The LRA-based estimates of the extent of four land-use categories (cropland, meadows/grassland, wetland, outland/woodland) were compared to corresponding estimates based on historical maps and aerial photographs from AD 1769–1823, 1837–1895, 1946 and 2005. Although the LRA approach tends to overestimate grassland cover by 10–30 % for the two earliest time periods, the reconstructed vegetation composition is generally in good agreement with estimates based on the historical records. Subsequently, the LRA approach was used to reconstruct the 200-year history of local land-use dynamics at 20-year intervals around two small lakes. The qualitative assessment of difference approach , which requires fewer assumptions and parameters than LRA for objective evaluation of between-site differences in plant abundances, provides consistent results in general. Significant differences exist in the land-use history between the sites. Local catchment characteristics, such as soil conditions and wetland cover, appear important for the development of human impact on the landscape. Quantifi-cations of past vegetation dynamics provide information on the amplitude, frequency and duration of the land-use changes and their effects on terrestrial and aquatic ecosystems , and should be taken into account when nature conservation strategies are developed

“Ordinary Artists?” An Interview with Howard S. Becker

M.P. & G.B.: Could you tell us about the origin of the expression “dance musicians” in Outsiders? What did it mean at the time? H.S.B.: The reason I added the adjective “dance” to the noun “musicians” was to distinguish the people I was talking about from other kinds of musicians playing in other organized settings at the same period. Who were these others? I think I was probably quite aware of at least the following specialized groups who were in the musicians’ union but were not “my kind of..

« Artistes ordinaires ? » Entretien avec Howard S. Becker

M.P. & G.B. : Pouvez-vous nous parler de l’origine de l’expression « musiciens de danse » dans Outsiders ? Qu’est-ce que cela signifiait à l’époque ? H.S.B. : J’ai ajouté le complément « de danse » au nom « musiciens » de manière à faire la différence entre les gens dont je parlais et les autres musiciens qui jouaient dans d’autres contextes organisés à la même époque. Qui étaient-ils ? J’en connaissais au moins quelques-uns. Par exemple, il y avait ceux qui adhéraient au syndicat des musicie..