792 research outputs found
Linearized Tensor Renormalization Group Algorithm for Thermodynamics of Quantum Lattice Models
A linearized tensor renormalization group (LTRG) algorithm is proposed to
calculate the thermodynamic properties of one-dimensional quantum lattice
models, that is incorporated with the infinite time-evolving block decimation
technique, and allows for treating directly the two-dimensional transfer-matrix
tensor network. To illustrate its feasibility, the thermodynamic quantities of
the quantum XY spin chain are calculated accurately by the LTRG, and the
precision is shown to be comparable with (even better than) the transfer matrix
renormalization group (TMRG) method. Unlike the TMRG scheme that can only deal
with the infinite chains, the present LTRG algorithm could treat both finite
and infinite systems, and may be readily extended to boson and fermion quantum
lattice models.Comment: published versio
Measurement of discrete energy-level spectra in individual chemically synthesized gold nanoparticles.
We form single-electron transistors from individual chemically-synthesized
gold nanoparticles, 5-15 nm in diameter, with monolayers of organic molecules
serving as tunnel barriers. These devices allow us to measure the discrete
electronic energy levels of individual gold nanoparticles that are, by virtue
of chemical synthesis, well-defined in their composition, size and shape. We
show that the nanoparticles are non-magnetic and have spectra in good accord
with random-matrix-theory predictions taking into account strong spin-orbit
coupling.Comment: 15 pages, 5 figures; corrected typos, added journal referenc
Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
Van der Waals heterostructures have recently emerged as a new class of
materials, where quantum coupling between stacked atomically thin
two-dimensional (2D) layers, including graphene, hexagonal-boron nitride, and
transition metal dichalcogenides (MX2), give rise to fascinating new phenomena.
MX2 heterostructures are particularly exciting for novel optoelectronic and
photovoltaic applications, because 2D MX2 monolayers can have an optical
bandgap in the near-infrared to visible spectral range and exhibit extremely
strong light-matter interactions. Theory predicts that many stacked MX2
heterostructures form type-II semiconductor heterojunctions that facilitate
efficient electron-hole separation for light detection and harvesting. Here we
report the first experimental observation of ultrafast charge transfer in
photo-excited MoS2/WS2 heterostructures using both photoluminescence mapping
and femtosecond (fs) pump-probe spectroscopy. We show that hole transfer from
the MoS2 layer to the WS2 layer takes place within 50 fs after optical
excitation, a remarkable rate for van der Waals coupled 2D layers. Such
ultrafast charge transfer in van der Waals heterostructures can enable novel 2D
devices for optoelectronics and light harvesting
Quantum Compressed Sensing with Unsupervised Tensor-Network Machine Learning
We propose tensor-network compressed sensing (TNCS) by combining the ideas of
compressed sensing, tensor network (TN), and machine learning, which permits
novel and efficient quantum communications of realistic data. The strategy is
to use the unsupervised TN machine learning algorithm to obtain the entangled
state that describes the probability distribution of a huge
amount of classical information considered to be communicated. To transfer a
specific piece of information with , our proposal is to encode
such information in the separable state with the minimal distance to the
measured state that is obtained by partially measuring on
in a designed way. To this end, a measuring protocol analogous
to the compressed sensing with neural-network machine learning is suggested,
where the measurements are designed to minimize uncertainty of information from
the probability distribution given by . In this way, those who
have can reliably access the information by simply measuring on
. We propose q-sparsity to characterize the sparsity of quantum
states and the efficiency of the quantum communications by TNCS. The high
q-sparsity is essentially due to the fact that the TN states describing nicely
the probability distribution obey the area law of entanglement entropy. Testing
on realistic datasets (hand-written digits and fashion images), TNCS is shown
to possess high efficiency and accuracy, where the security of communications
is guaranteed by the fundamental quantum principles.Comment: 5+6 pages, 3+6 figures. Essential changes and new data were added to
this new versio
Efficacy of the Combination of Voriconazole and Caspofungin in Experimental Pulmonary Aspergillosis by Different Aspergillus Species
OBJECTIVES: Invasive pulmonary aspergillosis (IPA) caused by Aspergillus fumigatus, Aspergillus flavus, or Aspergillus niger is associated with high mortality. We evaluated the efficacy and compared the therapeutic effect differences of voriconazole (VRC) in combination with caspofungin (CAS) in transiently neutropenic rats infected by A. fumigatus, A. flavus, or A. niger. METHODS: Treatment groups consisted of VRC (10 mg/kg q12 h) monotherapy, CAS (1 mg/kg/day) monotherapy, combination of VRC (10 mg/kg q12 h) + CAS (1 mg/kg/day), and no drug for 10 consecutive days. The efficacy and the difference in the treatments were evaluated through prolongation of survival, reduction in serum galactomannan levels and residual fungal burden, and histological studies. RESULTS: For all the strains, the combination of VRC and CAS led to significant prolongation in survival (P < 0.05) and reduction in residual fungal burden (P < 0.05) compared with CAS alone, and decrease in serum galactomannan levels (P < 0.05) compared with either agent alone. The survival in the combined therapy groups was significantly improved compared to VRC monotherapy for the strains of A. flavus and A. niger (P < 0.05), but no significant difference for the strains of A. fumigatus (P > 0.05). CONCLUSIONS: Combination of VRC and CAS was synergistic in IPA by A. flavus and A. niger, but small efficacy benefits in IPA by A. fumigatus
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