12,447 research outputs found
A Soft Robotic Cover with Dual Thermal Display and Sensing Capabilities
We propose a new robotic cover prototype that achieves thermal display while
also being soft. We focus on the thermal cue because previous human studies
have identified it as part of the touch pleasantness. The robotic cover surface
can be regulated to the desired temperature by circulating water through a
thermally conductive pipe embedded in the cover, of which temperature is
controlled. Besides, an observer for estimating heat from human contact is
implemented; it can detect human interaction while displaying the desired
temperature without temperature sensing on the surface directly. We assessed
the validity of the prototype in experiments of temperature control and contact
detection by human hand
Mass Renormlization in the Nelson Model
The asymptotic behavior of the effective mass of the
so-called Nelson model in quantum field theory is considered, where
is an ultraviolet cutoff parameter of the model. Let be the bare mass of
the model. It is shown that for sufficiently small coupling constant
of the model, can be expanded as . A physical
folklore is that as . It is rigorously shown that
with some constants
, and .Comment: It has been published in International Journal of Mathematics and
Mathematical Sciences, vol. 2017, Article ID 476010
A study of the effect of forcing function characteristics on human operator dynamics in manual control
The effect of the spectrum of the forcing function on the human pilot dynamics in manual control was investigated. A simple compensatory tracking experiment was conducted, where the controlled element was of a second-order dynamics and the forcing function was a random noise having a dominant frequency. The dominant frequency and the power of the forcing function were two variable parameters during the experiment. The results show that the human pilot describing functions are dependent not only on the dynamics of the controlled element, but also on the characteristics of the forcing function. This suggests that the human pilot behavior should be expressed by the transfer function taking into consideration his ability to sense and predict the forcing function
Joint Entanglement of Topology and Polarization Enables Error-Protected Quantum Registers
Linear-optical systems can implement photonic quantum walks that simulate
systems with nontrivial topological properties. Here, such photonic walks are
used to jointly entangle polarization and winding number. This joint
entanglement allows information processing tasks to be performed with
interactive access to a wide variety of topological features. Topological
considerations are used to suppress errors, with polarization allowing easy
measurement and manipulation of qubits. We provide three examples of this
approach: production of two-photon systems with entangled winding number
(including topological analogs of Bell states), a topologically error-protected
optical memory register, and production of entangled topologicallyprotected
boundary states. In particular it is shown that a pair of quantum memory
registers, entangled in polarization and winding number, with
topologically-assisted error suppression can be made with qubits stored in
superpositions of winding numbers; as a result, information processing with
winding number-based qubits is a viable possibility
Directionally-unbiased unitary optical devices in discrete-time quantum walks
The optical beam splitter is a widely-used device in photonics-based quantum information processing. Specifically, linear optical networks demand large numbers of beam splitters for unitary matrix realization. This requirement comes from the beam splitter property that a photon cannot go back out of the input ports, which we call “directionally-biased”. Because of this property, higher dimensional information processing tasks suffer from rapid device resource growth when beam splitters are used in a feed-forward manner. Directionally-unbiased linear-optical devices have been introduced recently to eliminate the directional bias, greatly reducing the numbers of required beam splitters when implementing complicated tasks. Analysis of some originally directional optical devices and basic principles of their conversion into directionally-unbiased systems form the base of this paper. Photonic quantum walk implementations are investigated as a main application of the use of directionally-unbiased systems. Several quantum walk procedures executed on graph networks constructed using directionally-unbiased nodes are discussed. A significant savings in hardware and other required resources when compared with traditional directionally-biased beam-splitter-based optical networks is demonstrated.Accepted manuscriptPublished versio
Experimental demonstration of a directionally-unbiased linear-optical multiport
All existing optical quantum walk approaches are based on the use of
beamsplitters and multiple paths to explore the multitude of unitary
transformations of quantum amplitudes in a Hilbert space. The beamsplitter is
naturally a directionally biased device: the photon cannot travel in reverse
direction. This causes rapid increases in optical hardware resources required
for complex quantum walk applications, since the number of options for the
walking particle grows with each step. Here we present the experimental
demonstration of a directionally-unbiased linear-optical multiport, which
allows reversibility of photon direction. An amplitude-controllable probability
distribution matrix for a unitary three-edge vertex is reconstructed with only
linear-optical devices. Such directionally-unbiased multiports allow direct
execution of quantum walks over a multitude of complex graphs and in tensor
networks. This approach would enable simulation of complex Hamiltonians of
physical systems and quantum walk applications in a more efficient and compact
setup, substantially reducing the required hardware resources
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