This paper reports on the electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes (SWNTs) at low temperatures. The researchers measured the conductance of these ropes and observed a suppression of low-bias conductance below a few millivolts. They also observed dramatic peaks in conductance as a function of gate voltage, which modulates the number of electrons in the rope. These results are interpreted as evidence of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes. The study focuses on the transport properties of SWNT ropes, which are fabricated by aligning and connecting nanotubes to lithographically defined leads. The device geometry allows for four-terminal measurements, enabling the study of different segments of the rope. The researchers found that the conductance of the rope is strongly dependent on the gate voltage, with sharp peaks observed in the conductance as a function of gate voltage. These peaks are attributed to single-electron transport through a segment of a single tube. The researchers also observed a Coulomb gap in the I-V characteristics of the rope, which is a suppression of conductance at low biases. The width of this gap is related to the energy required to add an additional electron to the system. The results are consistent with the Coulomb blockade model, which predicts that the spacing between peaks in the conductance is determined by the energy required to add an electron to the system. The study also discusses the implications of these results for the understanding of transport in nanoscale systems. The researchers suggest that the transport in the rope is dominated by single-electron charging of a small region of the rope or a single tube within the rope. The results are consistent with the theoretical predictions for the energy levels and charging energy of SWNTs. The study highlights the importance of gate voltage in modulating the properties of the nanotubes and the potential for further experiments on individual single-walled nanotubes to explore the transport properties of these systems.This paper reports on the electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes (SWNTs) at low temperatures. The researchers measured the conductance of these ropes and observed a suppression of low-bias conductance below a few millivolts. They also observed dramatic peaks in conductance as a function of gate voltage, which modulates the number of electrons in the rope. These results are interpreted as evidence of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes. The study focuses on the transport properties of SWNT ropes, which are fabricated by aligning and connecting nanotubes to lithographically defined leads. The device geometry allows for four-terminal measurements, enabling the study of different segments of the rope. The researchers found that the conductance of the rope is strongly dependent on the gate voltage, with sharp peaks observed in the conductance as a function of gate voltage. These peaks are attributed to single-electron transport through a segment of a single tube. The researchers also observed a Coulomb gap in the I-V characteristics of the rope, which is a suppression of conductance at low biases. The width of this gap is related to the energy required to add an additional electron to the system. The results are consistent with the Coulomb blockade model, which predicts that the spacing between peaks in the conductance is determined by the energy required to add an electron to the system. The study also discusses the implications of these results for the understanding of transport in nanoscale systems. The researchers suggest that the transport in the rope is dominated by single-electron charging of a small region of the rope or a single tube within the rope. The results are consistent with the theoretical predictions for the energy levels and charging energy of SWNTs. The study highlights the importance of gate voltage in modulating the properties of the nanotubes and the potential for further experiments on individual single-walled nanotubes to explore the transport properties of these systems.