283 research outputs found
Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb
We report the experimental realization and characterization of one 60-mode
copy, and of two 30-mode copies, of a dual-rail quantum-wire cluster state in
the quantum optical frequency comb of a bimodally pumped optical parametric
oscillator. This is the largest entangled system ever created whose subsystems
are all available simultaneously. The entanglement proceeds from the coherent
concatenation of a multitude of EPR pairs by a single beam splitter, a
procedure which is also a building block for the realization of
hypercubic-lattice cluster states for universal quantum computing.Comment: Accepted by PRL. 5 pages, 5 figures + 14 pages, 9 figures of
supplemental material. Ver3: better experimental dat
Observation of triply coincident nonlinearities in periodically poled KTiOPO4
We report the simultaneous quasi-phase-matching of all three possible
nonlinearities for propagation along the X axis of periodocally poled (PP)
KTiOPO4 (KTP) for second-harmonic generation of 745 nm pulsed light from 1490nm
subpicosecond pulses in a PPKTP crystal with a 45.65 micrometer poling period.
This confirms the recent Sellmeier fits of KTP by K. Kato and E. Takaoka [Appl.
Opt. 41, 5040 (2002)]. Such coincident nonlinearities are of importance for
realizing compact sources of multipartite continuous-variable entanglement
[Pfister et al., Phys. Rev. A 70, 020302 (2004)] and we propose a new simpler
method for entangling four fields, based on this triple coincidence.Comment: 3 pages, 4 figures, submitted for publicatio
Weaving quantum optical frequency combs into continuous-variable hypercubic cluster states
Cluster states with higher-dimensional lattices that cannot be physically
embedded in three-dimensional space have important theoretical interest in
quantum computation and quantum simulation of topologically ordered
condensed-matter systems. We present a simple, scalable, top-down method of
entangling the quantum optical frequency comb into hypercubic-lattice
continuous-variable cluster states of a size of about 10^4 quantum field modes,
using existing technology. A hypercubic lattice of dimension D (linear, square,
cubic, hypercubic, etc.) requires but D optical parametric oscillators with
bichromatic pumps whose frequency splittings alone determine the lattice
dimensionality and the number of copies of the state.Comment: 8 pages, 5 figures, submitted for publicatio
Sample efficient graph classification using binary Gaussian boson sampling
We present a variation of a quantum algorithm for the machine learning task
of classification with graph-structured data. The algorithm implements a
feature extraction strategy that is based on Gaussian boson sampling (GBS) a
near term model of quantum computing. However, unlike the currently proposed
algorithms for this problem, our GBS setup only requires binary (light/no
light) detectors, as opposed to photon number resolving detectors. These
detectors are technologically simpler and can operate at room temperature,
making our algorithm less complex and less costly to implement on the physical
hardware. We also investigate the connection between graph theory and the
matrix function called the Torontonian which characterizes the probabilities of
binary GBS detection events
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
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