1,400 research outputs found
Creating high dimensional time-bin entanglement using mode-locked lasers
We present a new scheme to generate high dimensional entanglement between two
photonic systems. The idea is based on parametric down conversion with a
sequence of pump pulses generated by a mode-locked laser. We prove
experimentally the feasibility of this scheme by performing a Franson-type Bell
test using a 2-way interferometer with path-length difference equal to the
distance between 2 pump pulses. With this experiment, we can demonstrate
entanglement for a two-photon state of at least dimension D=11. Finally, we
propose a feasible experiment to show a Fabry-Perot like effect for a high
dimensional two-photon state.Comment: 5 pages, 5 figure
Long distance entanglement swapping with photons from separated sources
We report the first experimental realization of entanglement swapping over
large distances in optical fibers. Two photons separated by more than two km of
optical fibers are entangled, although they never directly interacted. We use
two pairs of time-bin entangled qubits created in spatially separated sources
and carried by photons at telecommunication wavelengths. A partial Bell state
measurement is performed with one photon from each pair which projects the two
remaining photons, formerly independent onto an entangled state. A visibility
high enough to violate a Bell inequality is reported, after both photons have
each travelled through 1.1 km of optical fiber.Comment: 4 pages, 3 figures, submitte
Ultrafast optical control of entanglement between two quantum dot spins
The interaction between two quantum bits enables entanglement, the
two-particle correlations that are at the heart of quantum information science.
In semiconductor quantum dots much work has focused on demonstrating single
spin qubit control using optical techniques. However, optical control of
entanglement of two spin qubits remains a major challenge for scaling from a
single qubit to a full-fledged quantum information platform. Here, we combine
advances in vertically-stacked quantum dots with ultrafast laser techniques to
achieve optical control of the entangled state of two electron spins. Each
electron is in a separate InAs quantum dot, and the spins interact through
tunneling, where the tunneling rate determines how rapidly entangling
operations can be performed. The two-qubit gate speeds achieved here are over
an order of magnitude faster than in other systems. These results demonstrate
the viability and advantages of optically controlled quantum dot spins for
multi-qubit systems.Comment: 24 pages, 5 figure
Roadmap on structured light
Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized.Peer ReviewedPostprint (published version
Atom lasers: production, properties and prospects for precision inertial measurement
We review experimental progress on atom lasers out-coupled from Bose-Einstein
condensates, and consider the properties of such beams in the context of
precision inertial sensing. The atom laser is the matter-wave analog of the
optical laser. Both devices rely on Bose-enhanced scattering to produce a
macroscopically populated trapped mode that is output-coupled to produce an
intense beam. In both cases, the beams often display highly desirable
properties such as low divergence, high spectral flux and a simple spatial mode
that make them useful in practical applications, as well as the potential to
perform measurements at or below the quantum projection noise limit. Both
devices display similar second-order correlations that differ from thermal
sources. Because of these properties, atom lasers are a promising source for
application to precision inertial measurements.Comment: This is a review paper. It contains 40 pages, including references
and figure
Multimode analysis of non-classical correlations in double well Bose-Einstein condensates
The observation of non-classical correlations arising in interacting two to
size weakly coupled Bose-Einstein condensates was recently reported by Esteve
et al. [Nature 455, 1216 (2008)]. In order to observe fluctuations below the
standard quantum limit, they utilized adiabatic passage to reduce the thermal
noise to below that of thermal equilibrium at the minimum realizable
temperature. We present a theoretical analysis that takes into account the
spatial degrees of freedom of the system, allowing us to calculate the expected
correlations at finite temperature in the system, and to verify the hypothesis
of adiabatic passage by comparing the dynamics to the idealized model.Comment: 12 pages, 7 figure
A compact and reconfigurable silicon nitride time-bin entanglement circuit
Photonic chip based time-bin entanglement has attracted significant attention
because of its potential for quantum communication and computation. Useful
time-bin entanglement systems must be able to generate, manipulate and analyze
entangled photons on a photonic chip for stable, scalable and reconfigurable
operation. Here we report the first time-bin entanglement photonic chip that
integrates time-bin generation, wavelength demultiplexing and entanglement
analysis. A two-photon interference fringe with an 88.4% visibility is measured
(without subtracting any noise), indicating the high performance of the chip.
Our approach, based on a silicon nitride photonic circuit, which combines the
low-loss characteristic of silica and tight integration features of silicon,
paves the way for scalable real-world quantum information processors.Comment: 4 pages, 5 figure
Generation and coherent control of pulsed quantum frequency combs
We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional states on-chip in a practical way have remained elusive due to the increasing complexity of the quantum circuitry needed to prepare and process such states. Here, we outline how high-dimensional, frequency-bin entangled, two-photon states can be generated at a stable, high generation rate by using a nested-cavity, actively mode-locked excitation of a nonlinear micro-cavity. This technique is used to produce pulsed quantum frequency combs. Moreover, we present how the quantum states can be coherently manipulated using standard telecommunications components such as programmable filters and electro-optic modulators. In particular, we show in detail how to accomplish state characterization measurements such as density matrix reconstruction, coincidence detection, and single photon spectrum determination. The presented methods form an accessible, reconfigurable, and scalable foundation for complex high-dimensional state preparation and manipulation protocols in the frequency domain
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