7,515 research outputs found
Transfer of Nonclassical Properties from A Microscopic Superposition to Macroscopic Thermal States in The High Temperature Limit
We present several examples where prominent quantum properties are
transferred from a microscopic superposition to thermal states at high
temperatures. Our work is motivated by an analogy of Schrodinger's cat paradox,
where the state corresponding to the virtual cat is a mixed thermal state with
a large average photon number. Remarkably, quantum entanglement can be produced
between thermal states with nearly the maximum Bell-inequality violation even
when the temperatures of both modes approach infinity.Comment: minor corrections, acknowledgments added, Phys.Rev.Lett., in pres
Observation and Spectroscopy of a Two-Electron Wigner Molecule in an Ultra-Clean Carbon Nanotube
Coulomb interactions can have a decisive effect on the ground state of
electronic systems. The simplest system in which interactions can play an
interesting role is that of two electrons on a string. In the presence of
strong interactions the two electrons are predicted to form a Wigner molecule,
separating to the ends of the string due to their mutual repulsion. This
spatial structure is believed to be clearly imprinted on the energy spectrum,
yet to date a direct measurement of such a spectrum in a controllable
one-dimensional setting is still missing. Here we use an ultra-clean suspended
carbon nanotube to realize this system in a tunable potential. Using tunneling
spectroscopy we measure the excitation spectra of two interacting carriers,
electrons or holes, and identify seven low-energy states characterized by their
spin and isospin quantum numbers. These states fall into two multiplets
according to their exchange symmetries. The formation of a strongly-interacting
Wigner molecule is evident from the small energy splitting measured between the
two multiplets, that is quenched by an order of magnitude compared to the
non-interacting value. Our ability to tune the two-electron state in space and
to study it for both electrons and holes provides an unambiguous demonstration
of the fundamental Wigner molecule state.Comment: SP and FK contributed equally to this wor
Heat exchanger for electrothermal devices
An improved electrothermal device is disclosed. An electrothermal thruster utilizes a generally cylindrical heat exchanger chamber to convert electricity to heat which raises the propellant temperature. A textured, high emissivity heat element radiatively transfers heat to the inner wall of this chamber that is ion beam morphologically controlled for high absorptivity. This, in turn, raises the temperature of a porous heat exchanger material in an annular chamber surrounding the cylindrical chamber. Propellant gas flows through the annular chamber and is heated by the heat exchanger material
The Mach-Zehnder and the Teleporter
We suggest a self-testing teleportation configuration for photon q-bits based
on a Mach-Zehnder interferometer. That is, Bob can tell how well the input
state has been teleported without knowing what that input state was. One could
imagine building a "locked" teleporter based on this configuration. The
analysis is performed for continuous variable teleportation but the arrangement
could equally be applied to discrete manipulations.Comment: 4 pages, 5 figure
Entanglement swapping using continuous variables
We investigate the efficacy with which entanglement can be teleported using a
continuous measurement scheme. We show that by using the correct gain for the
classical channel the degree of violation of locality that can be demonstrated
(using a CH type inequality) is {\it not} a function of the level of
entanglement squeezing used in the teleportation. This is possible because a
gain condition can always be choosen such that passage through the teleporter
is equivalent to pure attenuation of the input field.Comment: 8 pages, 4 figure
Secure Coherent-state Quantum Key Distribution Protocols with Efficient Reconciliation
We study the equivalence between a realistic quantum key distribution
protocol using coherent states and homodyne detection and a formal entanglement
purification protocol. Maximally-entangled qubit pairs that one can extract in
the formal protocol correspond to secret key bits in the realistic protocol.
More specifically, we define a qubit encoding scheme that allows the formal
protocol to produce more than one entangled qubit pair per coherent state, or
equivalently for the realistic protocol, more than one secret key bit. The
entanglement parameters are estimated using quantum tomography. We analyze the
properties of the encoding scheme and investigate its application to the
important case of the attenuation channel.Comment: REVTeX, 11 pages, 2 figure
Sensitive protein detection using an optical fibre long period grating sensor anchored with silica core gold shell nanoparticles
Copyright ©2014 Society of Photo-Optical Instrumentation Engineers.
This paper was published in the Proceedings of SPIE and is made available with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.An optical fibre long period grating (LPG), modified with a coating of silica gold (SiO2:Au) core/shell nanoparticles (NPs) deposited using the layer-by-layer (LbL) method, was employed for the development of a bio-sensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(hydrochloride ammonium) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The lowest detected concentration of SV was 19 nM using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film
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