151 research outputs found
Readout using Resonant Tunneling in Silicon Spin Qubits
Spin qubit systems are one of the promising candidates for quantum computing.
The quantum dot (QD) arrays are intensively investigated by many researchers.
Because the energy-difference between the up-spin and down-spin states is very
small, the detection of the qubit state is of prime importance in this field.
Moreover, many wires are required to control qubit systems. Therefore, the
integration of qubits and wires is also an important issue. In this study, the
measurement process of QD arrays is theoretically investigated using resonant
tunneling, controlled by a conventional transistor. It is shown that the number
of possible measurements during coherence time can exceed a hundred under the
backaction of the measurements owing to the nonlinear characteristics of
resonant tunneling. It is also discussed to read out the measurement results by
the conventional transistor.Comment: 11 pages, 13 figure
RpoN Mediates Tolerance to Tobramycin
Pseudomonas aeruginosa has developed diverse strategies to respond and adapt to antibiotic stress. Among the factors that modulate survival in the presence of antibiotics, alternative sigma factors play an important role. Here, we demonstrate that the alternative sigma factor RpoN (σ 54) promotes survival in the presence of tobramycin. The tobramycin-sensitive phenotype of logarithmic phase ΔrpoN mutant cells is suppressed by the loss of the alternative sigma factor RpoS. Transcriptional analysis indicated that RpoN positively regulates the expression of RsmA, an RNA-binding protein, in the P. aeruginosa stationary growth phase in a nutrient-rich medium. The loss of RpoS led to the upregulation of gacA expression in the nutrient-limited medium-grown stationary phase cells. Conversely, in the logarithmic growth phase, the ΔrpoS mutant demonstrated lower expression of gacA, underscoring a regulatory role of RpoS for GacA. Supplementation of tobramycin to stationary phase ΔrpoN mutant cells grown in nutrient-rich medium resulted in decreased expression of gacA, relA, and rpoS without altering the expression of rsmA relative to wild-type PAO1. The observed downregulation of gacA and relA in the ΔrpoN mutant in the presence of tobramycin could be reversed through the mutation of rpoS in the ΔrpoN mutant background. The tobramycin-tolerant phenotype of the ΔrpoNΔrpoS mutant logarithmic phase cells may be associated with the expression of relA, which remained unresponsive upon addition of tobramycin. The logarithmic phase ΔrpoS and ΔrpoNΔrpoS mutant cells demonstrated increased expression of gacA in response to tobramycin. Together, these results suggest that a complex regulatory interaction between RpoN, RpoS, the Gac/Rsm pathway, and RelA modulates the P. aeruginosa response to tobramycin
Steady-state solution for dark states using a three-level system in coupled quantum dots
Quantum dots (QDs) are one of the promising candidates of interconnection
between electromagnetic field and electrons in solid-state devices. Dark states
appear as a result of coherence between the electromagnetic fields and the
discrete energy levels of the system. Here, we theoretically solve the
steady-state solutions of the density matrix equations for a thee-level double
QD system and investigate the condition of the appearance of a dark state. We
also numerically show the appearance of the dark state by time-dependent
current characteristics.Comment: 5 pages, 5 figure
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