4,837 research outputs found
Quantum Information Processing with Delocalized Qubits under Global Control
Any technology for quantum information processing (QIP) must embody within it
quantum bits (qubits) and maintain control of their key quantum properties of
superposition and entanglement. Typical QIP schemes envisage an array of
physical systems, such as electrons or nuclei, with each system representing a
given qubit. For adequate control, systems must be distinguishable either by
physical separation or unique frequencies, and their mutual interactions must
be individually manipulable. These difficult requirements exclude many
nanoscale technologies where systems are densely packed and continuously
interacting. Here we demonstrate a new paradigm: restricting ourselves to
global control pulses we permit systems to interact freely and continuously,
with the consequence that qubits can become delocalized over the entire device.
We realize this using NMR studies of three carbon-13 nuclei in alanine,
demonstrating all the key aspects including a quantum mirror, one- and
two-qubit gates, permutation of densely packed qubits and Deutsch algorithms.Comment: 4 pages, 5 figure
Near-Optimal Adversarial Policy Switching for Decentralized Asynchronous Multi-Agent Systems
A key challenge in multi-robot and multi-agent systems is generating
solutions that are robust to other self-interested or even adversarial parties
who actively try to prevent the agents from achieving their goals. The
practicality of existing works addressing this challenge is limited to only
small-scale synchronous decision-making scenarios or a single agent planning
its best response against a single adversary with fixed, procedurally
characterized strategies. In contrast this paper considers a more realistic
class of problems where a team of asynchronous agents with limited observation
and communication capabilities need to compete against multiple strategic
adversaries with changing strategies. This problem necessitates agents that can
coordinate to detect changes in adversary strategies and plan the best response
accordingly. Our approach first optimizes a set of stratagems that represent
these best responses. These optimized stratagems are then integrated into a
unified policy that can detect and respond when the adversaries change their
strategies. The near-optimality of the proposed framework is established
theoretically as well as demonstrated empirically in simulation and hardware
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Cool White Polymer Coatings based on Glass Bubbles for Buildings.
While most selective emitter materials are inadequate or inappropriate for building applications, here we present a techno-economically viable optical coating by integrating glass bubbles within a polymer film. A controlled glass bubble volume concentration from 0 to 70% leads to a selective solar reflectivity increase from 0.06 to 0.92 while the mid-infrared emissivity remains above 0.85. Outdoor measurements show the polymer coating on a concrete surface can provide a temperature reduction up to 25 °C during the day when conduction and convection are limited and a net cooling power greater than 78 W/m2 at a cost less than $0.005/W. The impact of polymer coating on common buildings is estimated as potential annual energy savings of 2-12 MJ/m2 and CO2 emission savings of 0.3-1.5 kg/m2. More savings are expected for higher surface-area-to-volume-ratio buildings, and the polymer coating is also expected to resolve cooling issues for old buildings with no air conditioning
Mixing Customer Ingratiation into Evaluation: How Service Providers Judge and Evaluate Rideshare Experiences
Whereas consumer satisfaction is critical for the success of services, we research how providers evaluate customers in the sharing economy represented by the rideshare marketplace. We examine anticipated customer evaluation (ACE) as the underlying link and the provider\u27s sense of power as a moderator for the relationship between customer ingratiation and provider evaluations. We first conducted a field pilot study and analyzed the content of rideshare trips described by drivers. Then, we tested the conceptual framework in four experiments that manipulated different rideshare customer behaviors (self-presentation, other-enhancement, and customer conformity). Our study contributes to the consumer research literature by examining provider evaluation and discovering the peer-to-peer (P2P) dynamic evaluation mechanisms that adopt a two-way rating system
Robust Logic Gates and Realistic Quantum Computation
The composite rotation approach has been used to develop a range of robust
quantum logic gates, including single qubit gates and two qubit gates, which
are resistant to systematic errors in their implementation. Single qubit gates
based on the BB1 family of composite rotations have been experimentally
demonstrated in a variety of systems, but little study has been made of their
application in extended computations, and there has been no experimental study
of the corresponding robust two qubit gates to date. Here we describe an
application of robust gates to Nuclear Magnetic Resonance (NMR) studies of
approximate quantum counting. We find that the BB1 family of robust gates is
indeed useful, but that the related NB1, PB1, B4 and P4 families of tailored
logic gates are less useful than initially expected.Comment: 6 pages RevTex4 including 5 figures (3 low quality to save space).
Revised at request of referee and incorporting minor corrections and updates.
Now in press at Phys Rev
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