87 research outputs found
Parallel generation of quadripartite cluster entanglement in the optical frequency comb
Scalability and coherence are two essential requirements for the experimental
implementation of quantum information and quantum computing. Here, we report a
breakthrough toward scalability: the simultaneous generation of a record 15
quadripartite entangled cluster states over 60 consecutive cavity modes
(Qmodes), in the optical frequency comb of a single optical parametric
oscillator. The amount of observed entanglement was constant over the 60
Qmodes, thereby proving the intrnisic scalability of this system. The number of
observable Qmodes was restricted by technical limitations, and we
conservatively estimate the actual number of similar clusters to be at least
three times larger. This result paves the way to the realization of large
entangled states for scalable quantum information and quantum computing.Comment: 4 pages + 7 supplemental-info pages, 6+1 figures, accepted by
Physical Review Letters. One minor revision to main text. One error corrected
in Eq. (18) of Supplemental informatio
Entangling the optical frequency comb: simultaneous generation of multiple 2x2 and 2x3 continuous-variable cluster states in a single optical parametric oscillator
We report on our research effort to generate large-scale multipartite
optical-mode entanglement using as few physical resources as possible. We have
previously shown that cluster- and GHZ-type N-partite continuous-variable
entanglement can be obtained in an optical resonator that contains a suitably
designed second-order nonlinear optical medium, pumped by at most O(N^2)
fields. In this paper, we show that the frequency comb of such a resonator can
be entangled into an arbitrary number of independent 2x2 and 2x3
continuous-variable cluster states by a single optical parametric oscillator
pumped by just a few optical modes.Comment: Third version has corrected eqs. (10-14) and revised notation "Q" in
lieu of "X" for amplitude quadrature operato
Playing the quantum harp: Multipartite squeezing and entanglement of harmonic oscillators
The frequency comb of an optical resonator is a naturally large set of exquisitely well defined quantum systems, such as in the broadband mode-locked lasers which have redefined time/frequency metrology and ultraprecise measurements in recent years. High coherence can therefore be expected in the quantum version of the frequency comb, in which nonlinear interactions couple different cavity modes, as can be modeled by different forms of graph states. We show that is possible to thereby generate states of interest to quantum metrology and computing, such as multipartite entangled cluster and Greenberger-Horne-Zeilinger states
Nonlocal restoration of two-mode squeezing in the presence of strong optical loss
We present the experimental realization of a theoretical effect discovered by
Olivares and Paris, in which a pair of entangled optical beams undergoing
independent losses can see nonlocal correlations restored by the use of a
nonlocal resource correlating the losses. Twin optical beams created in an
entangled Einstein-Podolsky-Rosen (EPR) state by an optical parametric
oscillator above threshold were subjected to 50% loss from beamsplitters in
their paths. The resulting severe degradation of the signature quantum
correlations observed between the two beams was then suppressed when another,
independent EPR state impinged upon the other input ports of the beamsplitters,
effectively entangling the losses inflicted to the initial EPR state. The
additional EPR beam pair was classically coherent with the primary one but had
no quantum correlations with it. This result may find applications as a quantum
tap for entanglement.Comment: 14 pages, 6 figures, submitted for publicatio
Broadband amplitude squeezing in a periodically poled KTiOPO_4 waveguide
We generated -2.2 dB of broadband amplitude squeezing at 1064 nm in a
periodically poled KTiOPO_4 (PPKTP) waveguide, by coupling of the fundamental
and second harmonic continuous-wave fields. This is the largest amount of
squeezing obtained to date in a KTP waveguide, limited by propagation losses.
This result paves the way for further improvements by use of lower-loss buried
ion-exchanged waveguides.Comment: 3 pages, 2 figures, submitted for publicatio
Observed Relationship of Ozone air Pollution with Temperature and Emissions
Higher temperatures caused by increasing greenhouse gas concentrations are predicted to exacerbate photochemical smog if precursor emissions remain constant. We perform a statistical analysis of 21 years of ozone and temperature observations across the rural eastern U.S. The climate penalty factor is defined as the slope of the ozone/temperature relationship. For two precursor emission regimes, before and after 2002, the climate penalty factor was consistent across the distribution of ozone observations. Prior to 2002, ozone increased by an average of ~3.2 ppbv/°C. After 2002, power plant NOx emissions were reduced by 43%, ozone levels fell ~10%, and the climate penalty factor dropped to ~2.2 ppbv/°C. NOx controls are effective for reducing photochemical smog and might lessen the severity of projected climate change penalties. Air quality models should be evaluated against these observations, and the climate penalty factor metric may be useful for evaluating the response of ozone to climate change
The noise-lovers: cultures of speech and sound in second-century Rome
This chapter provides an examination of an ideal of the ‘deliberate speaker’, who aims to reflect time, thought, and study in his speech. In the Roman Empire, words became a vital tool for creating and defending in-groups, and orators and authors in both Latin and Greek alleged, by contrast, that their enemies produced babbling noise rather than articulate speech. In this chapter, the ideal of the deliberate speaker is explored through the works of two very different contemporaries: the African-born Roman orator Fronto and the Syrian Christian apologist Tatian. Despite moving in very different circles, Fronto and Tatian both express their identity and authority through an expertise in words, in strikingly similar ways. The chapter ends with a call for scholars of the Roman Empire to create categories of analysis that move across different cultural and linguistic groups. If we do not, we risk merely replicating the parochialism and insularity of our sources.Accepted manuscrip
Experimental continuous-variable entanglement from a phase-difference-locked optical parametric oscillator
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