69 research outputs found
Dioecious Silene latifolia plants show sexual dimorphism in the vegetative stage
<p>Abstract</p> <p>Background</p> <p>Prior to this study, no differences in gene expression between male and female dioecious plants in the vegetative state had been detected. Among dioecious plants displaying sexual dimorphism, <it>Silene latifolia </it>is one of the most studied species. Although many sexually dimorphic traits have been described in <it>S. latifolia</it>, all of them are quantitative, and they usually become apparent only after the initiation of flowering.</p> <p>Results</p> <p>We present RT-PCR-based evidence that in <it>S. latifolia</it>, sexual dimorphism in gene expression is present long before the initiation of flowering. We describe three ESTs that show sex-specific (two male specific and one female specific) transcription at the rosette stage before the first flowering season.</p> <p>Conclusions</p> <p>To our knowledge, this study provides the first molecular evidence of early pre-flowering sexual dimorphism in angiosperms.</p
Programmable Multimode Quantum Networks
Entanglement between large numbers of quantum modes is the quintessential
resource for future technologies such as the quantum internet. Conventionally
the generation of multimode entanglement in optics requires complex layouts of
beam-splitters and phase shifters in order to transform the input modes in to
entangled modes. These networks need substantial modification for every new set
of entangled modes to be generated. Here we report on the highly versatile and
efficient generation of various multimode entangled states with the ability to
switch between different linear optics networks in real time. By defining our
modes to be combinations of different spatial regions of one beam, we may use
just one pair of multi-pixel detectors each with M photodiodes in order to
measure N entangled modes, with a maximum number of N=M modes. We program
virtual networks that are fully equivalent to the physical linear optics
networks they are emulating. We present results for N=2 up to N=8 entangled
modes here, including N=2,3,4 cluster states. Our approach introduces
flexibility and scalability to multimode entanglement, two important attributes
that are highly sought after in state of the art devices.Comment: 10 pages, 5 figures, 2 tables, comments welcome
Measurement-Based Noiseless Linear Amplification for Quantum Communication
Entanglement distillation is an indispensable ingredient in extended quantum
communication networks. Distillation protocols are necessarily
non-deterministic and require advanced experimental techniques such as
noiseless amplification. Recently it was shown that the benefits of noiseless
amplification could be extracted by performing a post-selective filtering of
the measurement record to improve the performance of quantum key distribution.
We apply this protocol to entanglement degraded by transmission loss of up to
the equivalent of 100km of optical fibre. We measure an effective entangled
resource stronger than that achievable by even a maximally entangled resource
passively transmitted through the same channel. We also provide a
proof-of-principle demonstration of secret key extraction from an otherwise
insecure regime. The measurement-based noiseless linear amplifier offers two
advantages over its physical counterpart: ease of implementation and near
optimal probability of success. It should provide an effective and versatile
tool for a broad class of entanglement-based quantum communication protocols.Comment: 7+3 pages, 5+1 figures, close to published versio
Optomechanical magnetometry with a macroscopic resonator
We demonstrate a centimeter-scale optomechanical magnetometer based on a
crystalline whispering gallery mode resonator. The large size of the resonator
allows high magnetic field sensitivity to be achieved in the hertz to kilohertz
frequency range. A peak sensitivity of 131 pT per root Hz is reported, in a
magnetically unshielded non-cryogenic environment and using optical power
levels beneath 100 microWatt. Femtotesla range sensitivity may be possible in
future devices with further optimization of laser noise and the physical
structure of the resonator, allowing applications in high-performance
magnetometry
Multipartite Einstein-Podolsky-Rosen steering and genuine tripartite entanglement with optical networks
The Einstein-Podolsky-Rosen (EPR) paradox established a link between
entanglement and nonlocality in quantum mechanics. EPR steering is the
nonlocality associated with the EPR paradox and has traditionally only been
investigated between two parties. Here, we present the first experimental
observations of multipartite EPR steering, and of the genuine tripartite
continuous variable entanglement of three mesoscopic optical systems. We
explore different linear optics networks - each one with optimised asymmetries
- that create multipartite steerable states containing different numbers of
quantised optical modes (qumodes). By introducing asymmetric loss on a 7-qumode
state, we characterize 8 regimes of directional steering, showing that N + 1
regimes exist for an N-qumode state. Further, we reveal the directional
monogamy of steering, and experimentally demonstrate continuous variable
one-sided semi device-independent quantum secret sharing. Our methods establish
principles for the development of multiparty quantum communication protocols
with asymmetric observers, and can be extended to qubits, whether photonic,
atomic, superconducting, or otherwise.Comment: 7 pages, 4 figures. Comments are most welcome. Edited version to
appear Jan 2015 in peer-reviewed journa
Violation of Bells inequality using continuous variable measurements
A Bell inequality is a fundamental test to rule out local hidden variable
model descriptions of correlations between two physically separated systems.
There have been a number of experiments in which a Bell inequality has been
violated using discrete-variable systems. We demonstrate a violation of Bells
inequality using continuous variable quadrature measurements. By creating a
four-mode entangled state with homodyne detection, we recorded a clear
violation with a Bell value of . This opens new
possibilities for using continuous variable states for device independent
quantum protocols.Comment: 5 pages, 4 figures, lette
Demonstration of Quadrature Squeezed Surface-Plasmons in a Gold Waveguide
We report on the efficient generation, propagation, and re-emission of
squeezed long-range surface-plasmon polaritons (SPPs) in a gold waveguide.
Squeezed light is used to excite the non-classical SPPs and the re-emitted
quantum state is fully quantum characterized by complete tomographic
reconstruction of the density matrix. We find that the plasmon-assisted
transmission of non-classical light in metallic waveguides can be described by
a Hamiltonian analogue to a beam splitter. This result is explained
theoretically
Subdiffraction-Limited Quantum Imaging within a Living Cell
We report both subdiffraction-limited quantum metrology and quantum-enhanced spatial resolution for the first time in a biological context. Nanoparticles are tracked with quantum-correlated light as they diffuse through an extended region of a living cell in a quantum-enhanced photonic-force microscope. This allows spatial structure within the cell to be mapped at length scales down to 10 nm. Control experiments in water show a 14% resolution enhancement compared to experiments with coherent light. Our results confirm the long-standing prediction that quantum-correlated light can enhance spatial resolution at the nanoscale and in biology. Combined with state-of-the-art quantum light sources, this technique provides a path towards an order of magnitude improvement in resolution over similar classical imaging techniques
Experimental demonstration of Gaussian protocols for one-sided device-independent quantum key distribution
Nonlocal correlations, a longstanding foundational topic in quantum
information, have recently found application as a resource for cryptographic
tasks where not all devices are trusted, for example in settings with a highly
secure central hub, such as a bank or government department, and less secure
satellite stations which are inherently more vulnerable to hardware "hacking"
attacks. The asymmetric phenomena of Einstein-Podolsky-Rosen steering plays a
key role in one-sided device-independent quantum key distribution (1sDI-QKD)
protocols. In the context of continuous-variable (CV) QKD schemes utilizing
Gaussian states and measurements, we identify all protocols that can be 1sDI
and their maximum loss tolerance. Surprisingly, this includes a protocol that
uses only coherent states. We also establish a direct link between the relevant
EPR steering inequality and the secret key rate, further strengthening the
relationship between these asymmetric notions of nonlocality and device
independence. We experimentally implement both entanglement-based and
coherent-state protocols, and measure the correlations necessary for 1sDI key
distribution up to an applied loss equivalent to 7.5 km and 3.5 km of optical
fiber transmission respectively. We also engage in detailed modelling to
understand the limits of our current experiment and the potential for further
improvements. The new protocols we uncover apply the cheap and efficient
hardware of CVQKD systems in a significantly more secure setting.Comment: Addition of experimental results and (several) new author
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