362 research outputs found
Approach to accurately measuring the speed of optical precursors
Precursors can serve as a bound on the speed of information with dispersive
medium. We propose a method to identify the speed of optical precursors using
polarization-based interference in a solid-state device, which can bound the
accuracy of the precursors' speed to less than with conventional
experimental conditions. Our proposal may have important implications for
optical communications and fast information processing.Comment: 4 pages, 4 figure
Experimental detection of quantum coherent evolution through the violation of Leggett-Garg-type inequalities
We discuss the use of inequalities of the Leggett-Garg type (LGtI) to witness
quantum coherence and present the first experimental violation of this type of
inequalities using a light-matter interfaced system. By separately benchmarking
the Markovian character of the evolution and the translational invariance of
the conditional probabilities, the observed violation of a LGtI is attributed
to the quantum coherent character of the process. These results provide a
general method to benchmark `quantumness' when the absence of memory effects
can be independently certified and confirm the persistence of quantum coherent
features within systems of increasing complexity.Comment: published version, including supplementary materia
Phase Compensation Enhancement of Photon Pair Entanglement Generated from Biexciton Decays in Quantum Dots
Exciton fine-structure splittings within quantum dots introduce phase
differences between the two biexciton decay paths that greatly reduce the
entanglement of photon pairs generated via biexciton recombination. We analyze
this problem in the frequency domain and propose a practicable method to
compensate the phase difference by inserting a spatial light modulator, which
substantially improves the entanglement of the photon pairs without any loss.Comment: 4 pages, 3 figure
Nonclassical photon-pair source based on noiseless photon echo
The Duan-Lukin-Cirac-Zoller (DLCZ) scheme is a potential method to establish
remote entanglements and realize large-scale quantum networks. Here we propose
a DLCZ-like scheme based on the noiseless photon echo in rare-earth ion-doped
crystals. Correlated photon pairs with a controllable delay can be created by
the direct optical rephasing. Theoretical analysis indicates that the protocol
is efficient in the low-optical-depth regime. This protocol could be feasibly
implemented to establish long-lived quantum correlations between a photon and a
spin-wave excitation in rare-earth ion-doped crystals
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