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71.
We propose a method for simulating (2+1)D compact lattice quantum-electrodynamics, using ultracold atoms in optical lattices. In our model local Bose-Einstein condensates' (BECs) phases correspond to the electromagnetic vector potential, and the local number operators represent the conjugate electric field. The well-known gauge-invariant Kogut-Susskind Hamiltonian is obtained as an effective low-energy theory. The field is then coupled to external static charges. We show that in the strong coupling limit this gives rise to "electric flux tubes" and to confinement. This can be observed by measuring the local density deviations of the BECs, and is expected to hold even, to some extent, outside the perturbative calculable regime. 相似文献
72.
In this paper we consider the problem of determining whether an unknown arithmetic circuit, for which we have oracle access,
computes the identically zero polynomial. This problem is known as the black-box polynomial identity testing (PIT) problem.
Our focus is on polynomials that can be written in the form f([`(x)]) = ?i = 1k hi ([`(x)]) ·gi ([`(x)])f(\bar x) = \sum\nolimits_{i = 1}^k {h_i (\bar x) \cdot g_i (\bar x)} , where each h
i
is a polynomial that depends on only ρ linear functions, and each g
i
is a product of linear functions (when h
i
= 1, for each i, then we get the class of depth-3 circuits with k multiplication gates, also known as ΣΠΣ(k) circuits, but the general case is much richer). When max
i
(deg(h
i
· g
i
)) = d we say that f is computable by a ΣΠΣ(k; d;ρ) circuit. We obtain the following results.
1. |
A deterministic black-box identity testing algorithm for ΣΠΣ(k; d;ρ) circuits that runs in quasi-polynomial time (for ρ=polylog(n+d)). In particular this gives the first black-box quasi-polynomial time PIT algorithm for depth-3 circuits with k multiplication gates. 相似文献
73.
Shaked Uzi-Gavrilov Zohar Tik Omer Sabti Prof. Michael M. Meijler 《Angewandte Chemie (International ed. in English)》2023,62(29):e202300585
Chemical communication between competing bacteria in multi-species environments often enables both species to adapt and survive, and perhaps even thrive. P. aeruginosa and S. aureus are two bacterial pathogens found in natural biofilms, especially in the lungs of cystic fibrosis (CF) patients, where recent studies showed that there is often cooperation between the two species, leading to increased disease severity and antibiotic resistance. However, the mechanisms behind this cooperation are poorly understood. In this study, we analyzed co-cultured biofilms in various settings, and we applied untargeted mass spectrometry-based metabolomics analyses, combined with synthetic validation of candidate compounds. We unexpectedly discovered that S. aureus can convert pyochelin into pyochelin methyl ester, an analogue of pyochelin with reduced affinity for iron (III). This conversion allows S. aureus to coexist more readily with P. aeruginosa and unveils a mechanism underlying the formation of robust dual-species biofilms. 相似文献
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