Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory

Photonics is a promising platform for quantum technologies. However, photon sources and two-photon gates currently only operate probabilistically. Large-scale photonic processing will therefore be impossible without a multiplexing strategy to actively select successful events. High time-bandwidth-product quantum memories - devices that store and retrieve single photons on-demand - provide an efficient remedy via active synchronisation. Here we interface a GHz-bandwidth heralded single-photon source and a room-temperature Raman memory with a time-bandwidth product exceeding 1000. We store heralded single photons and observe a clear influence of the input photon statistics on the retrieved light, which agrees with our theoretical model. The preservation of the stored field's statistics is limited by four-wave-mixing noise, which we identify as the key remaining challenge in the development of practical memories for scalable photonic information processing

Model of Inhomogeneous Impurity Distribution in Fermi Superfluids

The standard treatment of impurities in metals assumes a homogeneous distribution of impurities. In this paper we study distributions that are inhomogeneous. We discuss in detail the "isotropic inhomogeneous scattering model" which takes into account the spatially varying scattering on the scale of the superfluid coherence length. On a large scale the model reduces to a homogeneous medium with renormalized parameter values. We apply the model to superfluid 3He, where porous aerogel acts as the impurity. We calculate the transition temperature Tc, the order parameter, and the superfluid density. Both A- and B-like phases are considered. Two different types of behavior are identified for the temperature dependence of the order parameter. We compare the calculations with experiments on 3He in aerogel. We find that most of the differences between experiments and the homogeneous theory can be explained by the inhomogeneous model. All our calculations are based on the quasiclassical theory of Fermi liquids. The parameters of this theory for superfluid 3He in aerogel are discussed.Comment: 14 pages, 9 figures, minor change

Mercury: Mid-infrared (7.3 - 13.5 microns) spectroscopic observations showing features characteristic of plagioclase

Mid-infrared spectroscopic observations of the surface of Mercury are reported for the wavelength range 7.3 to 13.5 microns. The observed spectral radiance emanated from equatorial and low latitude regions between 110-130 deg Mercurian longitude. The area is primarily an intercrater plain. The spectra show distinct and recognizable features, the principal Christiansen emission peak being the most prominent. The Christiansen feature strongly suggests the presence of plagioclase (Ca,Na)(Al,Si)AlSi2O8, (in particular labradorite: Ab(50) - Ab(30)). In addition we have studied the effects of thermal gradients to gain insight into the effects of thermal conditions on the spectral radiance of rock samples. This simulates the thermophysical effects as the rotating surface of Mercury is alternately heated and cooled. The spectral features of the samples are retained; however, the relative and absolute amplitudes vary as illustrated by laboratory reflectance and emittance spectra from quartzite

Hidden spin-current conservation in 2d Fermi liquids

We report the existence of regimes of the two dimensional Fermi liquid that show unusual conservation of the spin current and may be tuned by varying some parameter like the density of fermions. We show that for reasonable models of the effective interaction the spin current may be conserved in general in 2d, not only for a particular regime. Low temperature spin waves propagate distinctively in these regimes and entirely new ``spin-acoustic'' modes are predicted for scattering-dominated temperature ranges. These new high-temperature propagating spin waves provide a clear signature for the experimental search of such regimes.Comment: 4 pages, no figures, revised version, accepted for pub. in the PR

Physical Electronics

Contains reports on four research projects

Activity-dependent silencing reveals functionally distinct itch-generating sensory neurons

The peripheral terminals of primary sensory neurons detect histamine and non-histamine itch-provoking ligands through molecularly distinct transduction mechanisms. It remains unclear, however, whether these distinct pruritogens activate the same or different afferent fibers. We utilized a strategy of reversibly silencing specific subsets of murine pruritogen-sensitive sensory axons by targeted delivery of a charged sodium-channel blocker and found that functional blockade of histamine itch did not affect the itch evoked by chloroquine or SLIGRL-NH2, and vice versa. Notably, blocking itch-generating fibers did not reduce pain-associated behavior. However, silencing TRPV1+ or TRPA1+ neurons allowed AITC or capsaicin respectively to evoke itch, implying that certain peripheral afferents may normally indirectly inhibit algogens from eliciting itch. These findings support the presence of functionally distinct sets of itch-generating neurons and suggest that targeted silencing of activated sensory fibers may represent a clinically useful anti-pruritic therapeutic approach for histaminergic and non-histaminergic pruritus

New Chiral Phases of Superfluid 3He Stabilized by Anisotropic Silica Aerogel

A rich variety of Fermi systems condense by forming bound pairs, including high temperature [1] and heavy fermion [2] superconductors, Sr2RuO4 [3], cold atomic gases [4], and superfluid 3He [5]. Some of these form exotic quantum states having non-zero orbital angular momentum. We have discovered, in the case of 3He, that anisotropic disorder, engineered from highly porous silica aerogel, stabilizes a chiral superfluid state that otherwise would not exist. Additionally, we find that the chiral axis of this state can be uniquely oriented with the application of a magnetic field perpendicular to the aerogel anisotropy axis. At suffciently low temperature we observe a sharp transition from a uniformly oriented chiral state to a disordered structure consistent with locally ordered domains, contrary to expectations for a superfluid glass phase [6].Comment: 6 pages, 4 figure, and Supplementary Informatio

Plasma-binding globulins and acute stress response

Within studies of acute stress physiology an increase in glucocorticoid secretion is thought to be the primary mediator of tissue response to stress. Corticosteroid-binding globulin may regulate tissue availability of steroids, but has not been considered a dynamic component of the acute stress response. Here, we examined CBG level over the common 60-minute time frame in an acute capture and handling protocol to investigate whether CBG capacity is dynamic or static over short stressors. Using a comparative approach, we measured CBG response to capture and handling stress in nine species of birds, representing five orders and nine families. CBG capacity significantly declined within 30-60 minutes of capture in five of the nine species examined. This decline may serve to significantly increase the level of corticosterone reaching tissues during acute stress. © Georg Thieme Verlag KG Stuttgart