45 research outputs found
The thermal and electrical properties of the promising semiconductor MXene Hf2CO2
In this work, we investigate the thermal and electrical properties of
oxygen-functionalized M2CO2 (M = Ti, Zr, Hf) MXenes using first-principles
calculations. Hf2CO2 is found to exhibit a thermal conductivity better than
MoS2 and phosphorene. The room temperature thermal conductivity along the
armchair direction is determined to be 86.25-131.2 Wm-1K-1 with a flake length
of 5-100 um, and the corresponding value in the zigzag direction is
approximately 42% of that in the armchair direction. Other important thermal
properties of M2CO2 are also considered, including their specific heat and
thermal expansion coefficients. The theoretical room temperature thermal
expansion coefficient of Hf2CO2 is 6.094x10-6 K-1, which is lower than that of
most metals. Moreover, Hf2CO2 is determined to be a semiconductor with a band
gap of 1.657 eV and to have high and anisotropic carrier mobility. At room
temperature, the Hf2CO2 hole mobility in the armchair direction (in the zigzag
direction) is determined to be as high as 13.5x103 cm2V-1s-1 (17.6x103
cm2V-1s-1), which is comparable to that of phosphorene. Broader utilization of
Hf2CO2 as a material for nanoelectronics is likely because of its moderate band
gap, satisfactory thermal conductivity, low thermal expansion coefficient, and
excellent carrier mobility. The corresponding thermal and electrical properties
of Ti2CO2 and Zr2CO2 are also provided here for comparison. Notably, Ti2CO2
presents relatively low thermal conductivity and much higher carrier mobility
than Hf2CO2, which is an indication that Ti2CO2 may be used as an efficient
thermoelectric material.Comment: 26 pages, 5 figures, 2 table
Experimental exploration of five-qubit quantum error correcting code with superconducting qubits
Quantum error correction is an essential ingredient for universal quantum
computing. Despite tremendous experimental efforts in the study of quantum
error correction, to date, there has been no demonstration in the realisation
of universal quantum error correcting code, with the subsequent verification of
all key features including the identification of an arbitrary physical error,
the capability for transversal manipulation of the logical state, and state
decoding. To address this challenge, we experimentally realise the
code, the so-called smallest perfect code that permits
corrections of generic single-qubit errors. In the experiment, having optimised
the encoding circuit, we employ an array of superconducting qubits to realise
the code for several typical logical states including the magic
state, an indispensable resource for realising non-Clifford gates. The encoded
states are prepared with an average fidelity of while with a high
fidelity of in the code space. Then, the arbitrary single-qubit
errors introduced manually are identified by measuring the stabilizers. We
further implement logical Pauli operations with a fidelity of
within the code space. Finally, we realise the decoding circuit and recover the
input state with an overall fidelity of , in total with gates.
Our work demonstrates each key aspect of the code and verifies
the viability of experimental realization of quantum error correcting codes
with superconducting qubits.Comment: 6 pages, 4 figures + Supplementary Material
HIV Protease Inhibitors Sensitize Human Head and Neck Squamous Carcinoma Cells to Radiation by Activating Endoplasmic Reticulum Stress
Background
Human head and neck squamous cell carcinoma (HNSCC) is the sixth most malignant cancer worldwide. Despite significant advances in the delivery of treatment and surgical reconstruction, there is no significant improvement of mortality rates for this disease in the past decades. Radiotherapy is the core component of the clinical combinational therapies for HNSCC. However, the tumor cells have a tendency to develop radiation resistance, which is a major barrier to effective treatment. HIV protease inhibitors (HIV PIs) have been reported with radiosensitizing activities in HNSCC cells, but the underlying cellular/molecular mechanisms remain unclear. Our previous study has shown that HIV PIs induce cell apoptosis via activation of endoplasmic reticulum (ER) stress. The aim of this study was to examine the role of ER stress in HIV PI-induced radiosensitivity in human HNSCC. Methodology and Principal Findings
HNSCC cell lines, SQ20B and FaDu, and the most commonly used HIV PIs, lopinavir and ritonavir (L/R), were used in this study. Clonogenic assay was used to assess the radiosensitivity. Cell viability, apoptosis and cell cycle were analyzed using Cellometer Vision CBA. The mRNA and protein levels of ER stress-related genes (eIF2α, CHOP, ATF-4, and XBP-1), as well as cell cycle related protein, cyclin D1, were detected by real time RT-PCR and Western blot analysis, respectively. The results demonstrated that L/R dose-dependently sensitized HNSCC cells to irradiation and inhibited cell growth. L/R-induced activation of ER stress was correlated to down-regulation of cyclin D1 expression and cell cycle arrest under G0/G1 phase. Conclusion and Significance
HIV PIs sensitize HNSCC cells to radiotherapy by activation of ER stress and induction of cell cycle arrest. Our results provided evidence that HIV PIs can be potentially used in combination with radiation in the treatment of HNSCC
Quantum Neuronal Sensing of Quantum Many-Body States on a 61-Qubit Programmable Superconducting Processor
Classifying many-body quantum states with distinct properties and phases of
matter is one of the most fundamental tasks in quantum many-body physics.
However, due to the exponential complexity that emerges from the enormous
numbers of interacting particles, classifying large-scale quantum states has
been extremely challenging for classical approaches. Here, we propose a new
approach called quantum neuronal sensing. Utilizing a 61 qubit superconducting
quantum processor, we show that our scheme can efficiently classify two
different types of many-body phenomena: namely the ergodic and localized phases
of matter. Our quantum neuronal sensing process allows us to extract the
necessary information coming from the statistical characteristics of the
eigenspectrum to distinguish these phases of matter by measuring only one
qubit. Our work demonstrates the feasibility and scalability of quantum
neuronal sensing for near-term quantum processors and opens new avenues for
exploring quantum many-body phenomena in larger-scale systems.Comment: 7 pages, 3 figures in the main text, and 13 pages, 13 figures, and 1
table in supplementary material