Universal quantum computation with temporal-mode bilayer square lattices

We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state.Comment: (v2) 14 pages, 5 figures, consistent with published version; (v1) 13 pages, 5 figure

Resistive Heating Induced by Streaming Cosmic Rays Around a Galaxy in the Early Universe

It is expected that cosmic rays (CRs) escape from high-redshift galaxies at redshift $z\sim 10 \, - \, 20$ because CRs are accelerated by supernova remnants of the first stars. Although ultraviolet and X-ray photons are widely considered the main source of heating of the intergalactic medium, CRs can also contribute to it. When the CRs propagate in the intergalactic medium, in addition to the heating process due to CR ionization, resistive heating occurs due to the electron return current induced by the streaming CRs. We evaluate the heating rate around a galaxy as a function of the distance from the galaxy. We find that the resistive heating induced by CRs dominates over the other heating processes in the vicinity of the galaxy $r \lesssim 10^2 \, \mathrm{kpc}$ until the temperature reaches $T\sim 10^4 \, \mathrm{K}$. We also recalculate the strength of the magnetic field generated by streaming CRs under the presence of X-ray heating and show that achieved strength can be about $1$ order of magnitude smaller when the X-ray heating is included. The presence of the "first" CRs could be confirmed from the characteristic signature of CR heating imprinted on the $21$-$\mathrm{cm}$ line map in future radio observations.Comment: 7 pages, 3 figures, submitted to MNRA

Demonstration of a Controlled-Phase Gate for Continuous-Variable One-Way Quantum Computation

We experimentally demonstrate a controlled-phase gate for continuous variables in a fully measurement-based fashion. In our scheme, the two independent input states of the gate, encoded in two optical modes, are teleported into a four-mode Gaussian cluster state. As a result, one of the entanglement links present in the initial cluster state appears in the two unmeasured output modes as the corresponding entangling gate acting on the input states. The genuine quantum character of this gate becomes manifest and is verified through the presence of entanglement at the output for a product two-mode coherent input state. By combining our controlled-phase gate with the recently reported module for universal single-mode Gaussian operations [R. Ukai et al., Phys. Rev. Lett. 106, 240504 (2011)], it is possible to implement universal Gaussian operations on arbitrary multi-mode quantum optical states in form of a fully measurement-based one-way quantum computation.Comment: 4 pages, 3 figure

Generation of one-million-mode continuous-variable cluster state by unlimited time-domain multiplexing

In recent quantum optical continuous-variable experiments, the number of fully inseparable light modes has drastically increased by introducing a multiplexing scheme either in the time domain or in the frequency domain. Here, modifying the time-domain multiplexing experiment reported in Nature Photonics 7, 982 (2013), we demonstrate successive generation of fully inseparable light modes for more than one million modes. The resulting multi-mode state is useful as a dual-rail CV cluster state. We circumvent the previous problem of optical phase drifts, which has limited the number of fully inseparable light modes to around ten thousands, by continuous feedback control of the optical system.Comment: 12 pages, 8 figure

Fluvoxamine Attenuated Endoplasmic Reticulum Stress-Induced Leptin Resistance

Increasing evidence indicates that endoplasmic reticulum stress (ER stress) is involved in the development of metabolic syndrome. However, pharmacological treatments targeting ER stress are not well understood. In the present study, we found that fluvoxamine, a selective serotonin reuptake inhibitor used for depression, can attenuate ER stress-induced “leptin resistance,” i.e., insensitivity to the anti-obesity hormone leptin. Treatment with tunicamycin, an ER stress-inducing reagent, caused cell death which was significantly inhibited by fluvoxamine. Leptin activates JAK2–STAT3 signaling. ER stress caused an impairment of leptin-induced STAT3 phosphorylation which was reversed by fluvoxamine. Fluvoxamine would be a novel leptin-sensitizing drug, which targets ER stress