879 research outputs found
Astronomical random numbers for quantum foundations experiments
Photons from distant astronomical sources can be used as a classical source
of randomness to improve fundamental tests of quantum nonlocality,
wave-particle duality, and local realism through Bell's inequality and
delayed-choice quantum eraser tests inspired by Wheeler's cosmic-scale
Mach-Zehnder interferometer gedankenexperiment. Such sources of random numbers
may also be useful for information-theoretic applications such as key
distribution for quantum cryptography. Building on the design of an
"astronomical random-number generator" developed for the recent "cosmic Bell"
experiment [Handsteiner et al., Phys. Rev. Lett. 118, 060401 (2017)], in this
paper we report on the design and characterization of a device that, with
20-nanosecond latency, outputs a bit based on whether the wavelength of an
incoming photon is greater than or less than 700 nm. Using the one-meter
telescope at the Jet Propulsion Laboratory (JPL) Table Mountain Observatory, we
generated random bits from astronomical photons in both color channels from 50
stars of varying color and magnitude, and from 12 quasars with redshifts up to
. With stars, we achieved bit rates of Hz /
m, limited by saturation for our single-photon detectors, and with quasars
of magnitudes between 12.9 and 16, we achieved rates between and Hz /m. For bright quasars, the resulting bitstreams exhibit
sufficiently low amounts of statistical predictability as quantified by the
mutual information. In addition, a sufficiently high fraction of bits generated
are of true astronomical origin in order to address both the locality and
freedom-of-choice loopholes when used to set the measurement settings in a test
of the Bell-CHSH inequality.Comment: 17 pages, 12 figures. References added and minor edits to match
published versio
Recommended from our members
Forward modeling of internal kinematic structures of disk galaxies in MaNGA
SDSS-IV MaNGA is a large IFU survey with a goal of observing ~ 104 galaxies by the survey’s end. MaNGA produces spatially resolved kinematic maps that describe the motions of stars and gas in each galaxy, but these maps include the effects of beam smearing. The primary objective of this project is the development, testing and validation of a code designed to accurately extract intrinsic kinematic models from spectroscopic measurements of disk galaxies observed by the MaNGA survey. The code uses a thin disk model including perturbations around circular orbits up to second order to describe bar, spiral and oval features. In this Thesis, we document our implementation of the algorithm and present a small sample of our results to demonstrate the behavior of our code. The code is available online at http://github.com/aleung12/manga/ under the MIT License.Astronom
Two-way quantum communication channels
We consider communication between two parties using a bipartite quantum
operation, which constitutes the most general quantum mechanical model of
two-party communication. We primarily focus on the simultaneous forward and
backward communication of classical messages. For the case in which the two
parties share unlimited prior entanglement, we give inner and outer bounds on
the achievable rate region that generalize classical results due to Shannon. In
particular, using a protocol of Bennett, Harrow, Leung, and Smolin, we give a
one-shot expression in terms of the Holevo information for the
entanglement-assisted one-way capacity of a two-way quantum channel. As
applications, we rederive two known additivity results for one-way channel
capacities: the entanglement-assisted capacity of a general one-way channel,
and the unassisted capacity of an entanglement-breaking one-way channel.Comment: 21 pages, 3 figure
High Hepatitis E Seroprevalence Among Displaced Persons in South Sudan.
AbstractLarge protracted outbreaks of hepatitis E virus (HEV) have been documented in displaced populations in Africa over the past decade though data are limited outside these exceptional settings. Serological studies can provide insights useful for improving surveillance and disease control. We conducted an age-stratified serological survey using samples previously collected for another research study from 206 residents of an internally displaced person camp in Juba, South Sudan. We tested serum for anti-HEV antibodies (IgM and IgG) and estimated the prevalence of recent and historical exposure to the virus. Using data on individuals' serostatus, camp arrival date, and state of origin, we used catalytic transmission models to estimate the relative risk of HEV infection in the camp compared with that in the participants' home states. The age-adjusted seroprevalence of anti-HEV IgG was 71% (95% confidence interval = 63-78), and 4% had evidence of recent exposure (IgM). We estimated HEV exposure rates to be more than 2-fold (hazard ratio = 2.3, 95% credible interval = 0.3-5.8) higher in the camp than in the participants' home states, although this difference was not statistically significant. HEV transmission may be higher than previously appreciated, even in the absence of reported cases. Improved surveillance in similar settings is needed to understand the burden of disease and minimize epidemic impact through early detection and response
Perturbation of Retinoid Homeostasis Increases Malformation Risk in Embryos Exposed to Pregestational Diabetes
Funding. This work was supported by funding from Hong Kong Research Grants Council General Research Fund project reference 441606 and 474109 to A.S.W.S., Y.C.L., C.C.W., P.J.M. and A.J.C..Peer reviewedPostprin
Lower bounds on the complexity of simulating quantum gates
We give a simple proof of a formula for the minimal time required to simulate
a two-qubit unitary operation using a fixed two-qubit Hamiltonian together with
fast local unitaries. We also note that a related lower bound holds for
arbitrary n-qubit gates.Comment: 6 page
- …