7,594 research outputs found
Experimental realization of Dicke states of up to six qubits for multiparty quantum networking
We report the first experimental generation and characterization of a
six-photon Dicke state. The produced state shows a fidelity of F=0.56+/-0.02
with respect to an ideal Dicke state and violates a witness detecting genuine
six-qubit entanglement by four standard deviations. We confirm characteristic
Dicke properties of our resource and demonstrate its versatility by projecting
out four- and five-photon Dicke states, as well as four-photon GHZ and W
states. We also show that Dicke states have interesting applications in
multiparty quantum networking protocols such as open-destination teleportation,
telecloning and quantum secret sharing.Comment: 4 pages, 4 figures, RevTeX
Option-implied information: What’s the vol surface got to do with it?
We find that option-implied information such as forward-looking variance, skewness and the variance risk premium are sensitive to the way the volatility surface is constructed. For some state-of-the-art volatility surfaces, the differences are economically surprisingly large and lead to systematic biases, especially for out-of-the-money put options. Estimates for risk-neutral variance differ across volatility surfaces by more than 10% on average, leading to variance risk premium estimates that differ by 60% on average. The variations are even larger for risk-neutral skewness. To overcome this problem, we propose a volatility surface that is built with a one-dimensional kernel regression. We assess its statistical accuracy relative to existing state-of-the-art parametric, semi- and non-parametric volatility surfaces by means of leave-one-out cross-validation, including the volatility surface of OptionMetrics. Based on 14 years of end-of-day and intraday S&P 500 and Euro Stoxx 50 option data we conclude that the proposed one-dimensional kernel regression represents option market information more accurately than existing approaches of the literature
Nanosecond Dynamics of Single-Molecule Fluorescence Resonance Energy Transfer
Motivated by recent experiments on photon statistics from individual dye
pairs planted on biomolecules and coupled by fluorescence resonance energy
transfer (FRET), we show here that the FRET dynamics can be modelled by
Gaussian random processes with colored noise. Using Monte-Carlo numerical
simulations, the photon intensity correlations from the FRET pairs are
calculated, and are turned out to be very close to those observed in
experiment. The proposed stochastic description of FRET is consistent with
existing theories for microscopic dynamics of the biomolecule that carries the
FRET coupled dye pairs.Comment: 8 pages, 1 figure. accepted to J.Phys.Chem.
Storage and recall of weak coherent optical pulses with an efficiency of 25%
We demonstrate experimentally a quantum memory scheme for the storage of weak
coherent light pulses in an inhomogeneously broadened optical transition in a
Pr^{3+}: YSO crystal at 2.1 K. Precise optical pumping using a frequency stable
(about 1kHz linewidth) laser is employed to create a highly controllable Atomic
Frequency Comb (AFC) structure. We report single photon storage and retrieval
efficiencies of 25%, based on coherent photon echo type re-emission in the
forward direction. The coherence property of the quantum memory is proved
through interference between a super Gaussian pulse and the emitted echo.
Backward retrieval of the photon echo emission has potential for increasing
storage and recall efficiency.Comment: 5,
Generation of a superposition of multiple mesoscopic states of radiation in a resonant cavity
Using resonant interaction between atoms and the field in a high quality
cavity, we show how to generate a superposition of many mesoscopic states of
the field. We study the quasi-probability distributions and demonstrate the
nonclassicality of the superposition in terms of the zeroes of the Q-function
as well as the negativity of the Wigner function. We discuss the decoherence of
the generated superposition state. We propose homodyne techniques of the type
developed by Auffeves et al [Phys. Rev. Lett. 91, 230405 (2003)] to monitor the
superposition of many mesoscopic states.Comment: submitted to Phys. Rev.
A Molecular Micromaser
We show that photoassociation of fermionic atoms into bosonic molecules
inside an optical lattice can be described using a Jaynes-Cummings Hamiltonian
with a nonlinear detuning. Using this equivalence to the Jaynes-Cummings
dynamics, we show how one can construct a micromaser for the molecular field in
each lattice site
On mechanisms that enforce complementarity
In a recent publication Luis and Sanchez-Soto arrive at the conclusion that
complementarity is universally enforced by random classical phase kicks. We
disagree. One could just as well argue that quantum entanglement is the
universal mechanism. Both claims of universality are unjustified, however.Comment: 4 page
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