The emergence of noncommutative target space in noncritical string theory

We show how a noncommutative phase space appears in a natural way in noncritical string theory, the noncommutative deformation parameter being the string coupling.Comment: 21 pages, 1 figure. By mistake a wrong figure was included in v

Quantum rolling tachyon

We consider the quantum treatment of the rolling tachyon background describing the decay of D-branes in the limit of weak string coupling. We focus on the propagation of an open string in the fluctuating background and show how the boundary string action is modified by quantum effects. A bilocal term in the boundary action is generated which, however, does not spoil the vanishing of the $\beta$ function at one loop. The propagation of an open string for large times is found to be very strongly suppressed.Comment: 13 page

Simple atomic quantum memory suitable for semiconductor quantum dot single photons

Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of $\delta f$ = 0.66~GHz the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For 50 ns storage time we measure $\eta_{\textrm{e2e}}^{\textrm{50ns}} = 3.4(3)\%$ \emph{end-to-end efficiency} of the fiber-coupled memory, with an \emph{total intrinsic efficiency} $\eta_{\textrm{int}} = 17(3)\%$. Straightforward technological improvements can boost the end-to-end-efficiency to $\eta_{\textrm{e2e}} \approx 35\%$; beyond that increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional readout noise level of $9\cdot 10^{-3}$ photons is dominated by atomic fluorescence, and for input pulses containing on average $\mu_{1}=0.27(4)$ photons the signal to noise level would be unity

How should novelty be valued in science?

<p>Box plot analysis of serum concentrations of sRAGE (A), esRAGE (B), S100A9 (C) and HMGB1 (D) in patients with CTEPH (n = 26) and controls (n = 33). Independent Student’s t-test was used to compare groups. <i>RAGE</i> receptor for advanced glycation endproducts, <i>sRAGE</i> soluble RAGE, <i>esRAGE</i> endogenous secretory RAGE, <i>S100A9</i> member of S100 family of Ca+ binding proteins, <i>HMGB1</i> high mobility group box1, <i>CTEPH</i> chronic thromboembolic pulmonary hypertension.</p

Decay widths of three-impurity states in the BMN correspondence

We extend the study of the quantum mechanics of BMN gauge theory to the sector of three scalar impurities at one loop and all genus. The relevant matrix elements of the non-planar one loop dilatation operator are computed in the gauge theory basis. After a similarity transform the BMN gauge theory prediction for the corresponding piece of the plane wave string Hamiltonian is derived and shown to agree with light-cone string field theory. In the three-impurity sector single string states are unstable for the decay into two-string states at leading order in g_2. The corresponding decay widths are computed.Comment: 30 pages, 3 figures. v2: references adde

Exploring de Sitter Space and Holography

We explore aspects of the physics of de Sitter (dS) space that are relevant to holography with a positive cosmological constant. First we display a nonlocal map that commutes with the de Sitter isometries, transforms the bulk-boundary propagator and solutions of free wave equations in de Sitter onto the same quantities in Euclidean anti-de Sitter (EAdS), and takes the two boundaries of dS to the single EAdS boundary via an antipodal identification. Second we compute the action of scalar fields on dS as a functional of boundary data. Third, we display a family of solutions to 3d gravity with a positive cosmological constant in which the equal time sections are arbitrary genus Riemann surfaces, and compute the action of these spaces as a functional of boundary data from the Einstein gravity and Chern-Simons gravity points of view. These studies suggest that if de Sitter space is dual to a Euclidean conformal field theory (CFT), this theory should involve two disjoint, but possibly entangled factors. We argue that these CFTs would be of a novel form, with unusual hermiticity conditions relating left movers and right movers. After exploring these conditions in a toy model, we combine our observations to propose that a holographic dual description of de Sitter space would involve a pure entangled state in a product of two of our unconventional CFTs associated with the de Sitter boundaries. This state can be constructed to preserve the de Sitter symmetries and and its decomposition in a basis appropriate to antipodal inertial observers would lead to the thermal properties of static patch.Comment: LaTeX, v2: references adde