3,177 research outputs found
Advantages of Unfair Quantum Ground-State Sampling
The debate around the potential superiority of quantum annealers over their
classical counterparts has been ongoing since the inception of the field by
Kadowaki and Nishimori close to two decades ago. Recent technological
breakthroughs in the field, which have led to the manufacture of experimental
prototypes of quantum annealing optimizers with sizes approaching the practical
regime, have reignited this discussion. However, the demonstration of quantum
annealing speedups remains to this day an elusive albeit coveted goal. Here, we
examine the power of quantum annealers to provide a different type of quantum
enhancement of practical relevance, namely, their ability to serve as useful
samplers from the ground-state manifolds of combinatorial optimization
problems. We study, both numerically by simulating ideal stoquastic and
non-stoquastic quantum annealing processes, and experimentally, using a
commercially available quantum annealing processor, the ability of quantum
annealers to sample the ground-states of spin glasses differently than
classical thermal samplers. We demonstrate that i) quantum annealers in general
sample the ground-state manifolds of spin glasses very differently than thermal
optimizers, ii) the nature of the quantum fluctuations driving the annealing
process has a decisive effect on the final distribution over ground-states, and
iii) the experimental quantum annealer samples ground-state manifolds
significantly differently than thermal and ideal quantum annealers. We
illustrate how quantum annealers may serve as powerful tools when complementing
standard sampling algorithms.Comment: 13 pages, 11 figure
Finding and Certifying (Near-)Optimal Strategies in Black-Box Extensive-Form Games
Often -- for example in war games, strategy video games, and financial
simulations -- the game is given to us only as a black-box simulator in which
we can play it. In these settings, since the game may have unknown nature
action distributions (from which we can only obtain samples) and/or be too
large to expand fully, it can be difficult to compute strategies with
guarantees on exploitability. Recent work \cite{Zhang20:Small} resulted in a
notion of certificate for extensive-form games that allows exploitability
guarantees while not expanding the full game tree. However, that work assumed
that the black box could sample or expand arbitrary nodes of the game tree at
any time, and that a series of exact game solves (via, for example, linear
programming) can be conducted to compute the certificate. Each of those two
assumptions severely restricts the practical applicability of that method. In
this work, we relax both of the assumptions. We show that high-probability
certificates can be obtained with a black box that can do nothing more than
play through games, using only a regret minimizer as a subroutine. As a bonus,
we obtain an equilibrium-finding algorithm with
convergence rate in the extensive-form game setting that does not rely on a
sampling strategy with lower-bounded reach probabilities (which MCCFR assumes).
We demonstrate experimentally that, in the black-box setting, our methods are
able to provide nontrivial exploitability guarantees while expanding only a
small fraction of the game tree.Comment: AAAI 202
Incorporating Self-Interest Into Information Systems Development: A Research Model
Information systems (IS) analysis and design has much to do with “people factors.” Basically, human beings are creatures of self-interest. This paper first proposes a theory of self-interest as the theoretical base and integrative approach to understand the phenomenon of IS development. Based upon the theory proposed, a series of research propositions are then advanced to lay the basis of specifying variables and hypotheses in future research. The two research questions explored are: (1) How does IS analysis and design connote self-interest? (2) How does self-interest affect IS quality
Mediator Interpretation and Faster Learning Algorithms for Linear Correlated Equilibria in General Extensive-Form Games
A recent paper by Farina & Pipis (2023) established the existence of
uncoupled no-linear-swap regret dynamics with polynomial-time iterations in
extensive-form games. The equilibrium points reached by these dynamics, known
as linear correlated equilibria, are currently the tightest known relaxation of
correlated equilibrium that can be learned in polynomial time in any finite
extensive-form game. However, their properties remain vastly unexplored, and
their computation is onerous. In this paper, we provide several contributions
shedding light on the fundamental nature of linear-swap regret. First, we show
a connection between linear deviations and a generalization of communication
deviations in which the player can make queries to a "mediator" who replies
with action recommendations, and, critically, the player is not constrained to
match the timing of the game as would be the case for communication deviations.
We coin this latter set the untimed communication (UTC) deviations. We show
that the UTC deviations coincide precisely with the linear deviations, and
therefore that any player minimizing UTC regret also minimizes linear-swap
regret. We then leverage this connection to develop state-of-the-art no-regret
algorithms for computing linear correlated equilibria, both in theory and in
practice. In theory, our algorithms achieve polynomially better per-iteration
runtimes; in practice, our algorithms represent the state of the art by several
orders of magnitude
Unravelling the Correlation of Electronic Structure and Carrier Dynamics in CuInS\u3csub\u3e2\u3c/sub\u3e Nanoparticles
In this work, we report the direct correlation of photoinduced carrier dynamics and electronic structure of CuInS2 (CIS) nanoparticles (NPs) using the combination of multiple spectroscopic techniques including steady-state X-ray absorption spectroscopy (XAS), optical transient absorption (OTA), and X-ray transient (XTA) absorption spectroscopy. XAS results show that CIS NPs contain a large amount of surface Cu atoms with ≪four-coordination, which is more severe in CIS NPs with shorter nucleation times, indicating the presence of more Cu defect states in CIS NPs with smaller size particles. Using the combination of OTA and XTA spectroscopy, we show that electrons are trapped at states with mainly In or S nature while holes are trapped in sites characteristic of Cu. While there is no direct correlation of ultrafast trapping dynamics with NP nucleation time, charge recombination is significantly inhibited in CIS NPs with larger particles. These results suggest the key roles that Cu defect sites play in carrier dynamics and imply the possibility to control the carrier dynamics by controlling the surface structure at the Cu site in CIS NPs
Unravelling the Correlation of Electronic Structure and Carrier Dynamics in CuInS2 Nanoparticles
In this work, we report the direct correlation of photoinduced carrier dynamics and electronic structure of CuInS2 (CIS) nanoparticles (NPs) using the combination of multiple spectroscopic techniques including steady-state X-ray absorption spectroscopy (XAS), optical transient absorption (OTA), and X-ray transient (XTA) absorption spectroscopy. XAS results show that CIS NPs contain a large amount of surface Cu atoms with ≪four-coordination, which is more severe in CIS NPs with shorter nucleation times, indicating the presence of more Cu defect states in CIS NPs with smaller size particles. Using the combination of OTA and XTA spectroscopy, we show that electrons are trapped at states with mainly In or S nature while holes are trapped in sites characteristic of Cu. While there is no direct correlation of ultrafast trapping dynamics with NP nucleation time, charge recombination is significantly inhibited in CIS NPs with larger particles. These results suggest the key roles that Cu defect sites play in carrier dynamics and imply the possibility to control the carrier dynamics by controlling the surface structure at the Cu site in CIS NPs
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