1,193 research outputs found
Hybrid algorithm simulating non-equilibrium steady states of an open quantum system
Non-equilibrium steady states are a focal point of research in the study of
open quantum systems. Previous variational algorithms for searching these
steady states have suffered from resource-intensive implementations due to
vectorization or purification of the system density matrix, requiring large
qubit resources and long-range coupling. In this work, we present a novel
variational quantum algorithm that efficiently searches for non-equilibrium
steady states by simulating the operator-sum form of the Lindblad equation. By
introducing the technique of random measurement, we are able to estimate the
nonlinear cost function while reducing the required qubit resources by half
compared to previous methods. Additionally, we prove the existence of the
parameter shift rule in our variational algorithm, enabling efficient updates
of circuit parameters using gradient-based classical algorithms. To demonstrate
the performance of our algorithm, we conduct simulations for dissipative
quantum transverse Ising and Heisenberg models, achieving highly accurate
results. Our approach offers a promising solution for effectively addressing
non-equilibrium steady state problems while overcoming computational
limitations and implementation challenges.Comment: 8 pages, 4 figure
Resonant Column Test on the Frozen Silt Soil Modulus and Damping at Different Temperatures
The shear modulus and damping ratio of frozen soil are thebasic parameters of its dynamic properties and are often testedwith the dynamic triaxial apparatus. However, the resonantcolumn apparatus is more suitable for the testing at the microstrainlevel. A resonant column apparatus was here used toidentify the varying modes with negative temperature of theinitial shear modulus, modulus ratio, and damping ratio of frozensilt. Correction factor curves indicate that the temperaturehas a great effect on the shear modulus and damping ratio offrozen silt. The curves also show that, within the sensitive stage,the temperature significantly affects the modulus and damping.Within the insensitive stage, the modulus and dampingwere insensitive to the temperature. The experimental resultsand analysis given here provide support for improving seismicdesign codes and offer reasonable parameters for seismicresponse analysis in engineering construction in cold regions
Tweet Recommendation with Graph Co-Ranking
As one of the most popular micro-blogging services, Twitter attracts millions of users, producing millions of tweets daily. Shared information through this service spreads faster than would have been possible with traditional sources, however the proliferation of user-generation content poses challenges to browsing and finding valuable information. In this paper we propose a graph-theoretic model for tweet recommendation that presents users with items they may have an interest in. Our model ranks tweets and their authors simultaneously using several networks: the social network connecting the users, the network connecting the tweets, and a third network that ties the two together. Tweet and author entities are ranked following a co-ranking algorithm based on the intuition that that there is a mutually reinforcing relationship between tweets and their authors that could be reflected in the rankings. We show that this framework can be parametrized to take into account user preferences, the popularity of tweets and their authors, and diversity. Experimental evaluation on a large dataset shows that our model outperforms competitive approaches by a large margin.
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