29,581 research outputs found
Entanglement verification with finite data
Suppose an experimentalist wishes to verify that his apparatus produces
entangled quantum states. A finite amount of data cannot conclusively
demonstrate entanglement, so drawing conclusions from real-world data requires
statistical reasoning. We propose a reliable method to quantify the weight of
evidence for (or against) entanglement, based on a likelihood ratio test. Our
method is universal in that it can be applied to any sort of measurements. We
demonstrate the method by applying it to two simulated experiments on two
qubits. The first measures a single entanglement witness, while the second
performs a tomographically complete measurement.Comment: 4 pages, 3 pretty picture
Geographical Coarsegraining of Complex Networks
We perform the renormalization-group-like numerical analysis of
geographically embedded complex networks on the two-dimensional square lattice.
At each step of coarsegraining procedure, the four vertices on each square box are merged to a single vertex, resulting in the coarsegrained
system of the smaller sizes. Repetition of the process leads to the observation
that the coarsegraining procedure does not alter the qualitative
characteristics of the original scale-free network, which opens the possibility
of subtracting a smaller network from the original network without destroying
the important structural properties. The implication of the result is also
suggested in the context of the recent study of the human brain functional
network.Comment: To appear in Phys. Rev. Let
On a Conjecture of Givental
These brief notes record our puzzles and findings surrounding Givental's
recent conjecture which expresses higher genus Gromov-Witten invariants in
terms of the genus-0 data. We limit our considerations to the case of a
projective line, whose Gromov-Witten invariants are well-known and easy to
compute. We make some simple checks supporting his conjecture.Comment: 13 pages, no figures; v.2: new title, minor change
Multi-keyword multi-click advertisement option contracts for sponsored search
In sponsored search, advertisement (abbreviated ad) slots are usually sold by
a search engine to an advertiser through an auction mechanism in which
advertisers bid on keywords. In theory, auction mechanisms have many desirable
economic properties. However, keyword auctions have a number of limitations
including: the uncertainty in payment prices for advertisers; the volatility in
the search engine's revenue; and the weak loyalty between advertiser and search
engine. In this paper we propose a special ad option that alleviates these
problems. In our proposal, an advertiser can purchase an option from a search
engine in advance by paying an upfront fee, known as the option price. He then
has the right, but no obligation, to purchase among the pre-specified set of
keywords at the fixed cost-per-clicks (CPCs) for a specified number of clicks
in a specified period of time. The proposed option is closely related to a
special exotic option in finance that contains multiple underlying assets
(multi-keyword) and is also multi-exercisable (multi-click). This novel
structure has many benefits: advertisers can have reduced uncertainty in
advertising; the search engine can improve the advertisers' loyalty as well as
obtain a stable and increased expected revenue over time. Since the proposed ad
option can be implemented in conjunction with the existing keyword auctions,
the option price and corresponding fixed CPCs must be set such that there is no
arbitrage between the two markets. Option pricing methods are discussed and our
experimental results validate the development. Compared to keyword auctions, a
search engine can have an increased expected revenue by selling an ad option.Comment: Chen, Bowei and Wang, Jun and Cox, Ingemar J. and Kankanhalli, Mohan
S. (2015) Multi-keyword multi-click advertisement option contracts for
sponsored search. ACM Transactions on Intelligent Systems and Technology, 7
(1). pp. 1-29. ISSN: 2157-690
Pretzelosity and quark orbital angular momentum
We calculate the pretzelosity distribution (), which is one
of the eight leading twist transverse momentum dependent parton distributions
(TMDs), in the light-cone formalism. We find that this quantity has a simple
relation with the quark orbital angular momentum distribution, thus it may
provide a new possibility to access the quark orbital angular momentum inside
the nucleon. The pretzelosity distribution can manifest itself through the
asymmetry in semi-inclusive deep inelastic scattering
process. We calculate the asymmetry at HERMES, COMPASS
and JLab kinematics, and present our prediction on different targets including
the proton, deuteron and neutron targets. Inclusion of transverse momentum cut
in data analysis could significantly enhance the
asymmetry for future measurements.Comment: 20 latex pages, 7 figures, to appear in PR
Entanglement and purity of single- and two-photon states
Whereas single- and two-photon wave packets are usually treated as pure
states, in practice they will be mixed. We study how entanglement created with
mixed photon wave packets is degraded. We find in particular that the
entanglement of a delocalized single-photon state of the electro-magnetic field
is determined simply by its purity. We also discuss entanglement for two-photon
mixed states, as well as the influence of a vacuum component.Comment: 11 pages, 10 figures, 1 debuting autho
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