4,380 research outputs found
Inferring the Rate-Length Law of Protein Folding
We investigate the rate-length scaling law of protein folding, a key
undetermined scaling law in the analytical theory of protein folding. We
demonstrate that chain length is a dominant factor determining folding times,
and that the unambiguous determination of the way chain length corre- lates
with folding times could provide key mechanistic insight into the folding
process. Four specific proposed laws (power law, exponential, and two stretched
exponentials) are tested against one an- other, and it is found that the power
law best explains the data. At the same time, the fit power law results in
rates that are very fast, nearly unreasonably so in a biological context. We
show that any of the proposed forms are viable, conclude that more data is
necessary to unequivocally infer the rate-length law, and that such data could
be obtained through a small number of protein folding experiments on large
protein domains
Real Time Dense Depth Estimation by Fusing Stereo with Sparse Depth Measurements
We present an approach to depth estimation that fuses information from a
stereo pair with sparse range measurements derived from a LIDAR sensor or a
range camera. The goal of this work is to exploit the complementary strengths
of the two sensor modalities, the accurate but sparse range measurements and
the ambiguous but dense stereo information. These two sources are effectively
and efficiently fused by combining ideas from anisotropic diffusion and
semi-global matching.
We evaluate our approach on the KITTI 2015 and Middlebury 2014 datasets,
using randomly sampled ground truth range measurements as our sparse depth
input. We achieve significant performance improvements with a small fraction of
range measurements on both datasets. We also provide qualitative results from
our platform using the PMDTec Monstar sensor. Our entire pipeline runs on an
NVIDIA TX-2 platform at 5Hz on 1280x1024 stereo images with 128 disparity
levels.Comment: 7 pages, 5 figures, 2 table
Quantum State Sensitivity of an Autoresonant Superconducting Circuit
When a frequency chirped excitation is applied to a classical high-Q
nonlinear oscillator, its motion becomes dynamically synchronized to the drive
and large oscillation amplitude is observed, provided the drive strength
exceeds the critical threshold for autoresonance. We demonstrate that when such
an oscillator is strongly coupled to a quantized superconducting qubit, both
the effective nonlinearity and the threshold become a non-trivial function of
the qubit-oscillator detuning. Moreover, the autoresonant threshold is
sensitive to the quantum state of the qubit and may be used to realize a high
fidelity, latching readout whose speed is not limited by the oscillator Q.Comment: 5 pages, 4 figure
1/f noise of Josephson-junction-embedded microwave resonators at single photon energies and millikelvin temperatures
We present measurements of 1/f frequency noise in both linear and
Josephson-junction-embedded superconducting aluminum resonators in the low
power, low temperature regime - typical operating conditions for
superconducting qubits. The addition of the Josephson junction does not result
in additional frequency noise, thereby placing an upper limit for fractional
critical current fluctuations of (Hz) at 1 Hz for
sub-micron, shadow evaporated junctions. These values imply a minimum dephasing
time for a superconducting qubit due to critical current noise of 40 -- 1400
s depending on qubit architecture. Occasionally, at temperatures above 50
mK, we observe the activation of individual fluctuators which increase the
level of noise significantly and exhibit Lorentzian spectra
Measurement-induced qubit state mixing in circuit QED from up-converted dephasing noise
We observe measurement-induced qubit state mixing in a transmon qubit
dispersively coupled to a planar readout cavity. Our results indicate that
dephasing noise at the qubit-readout detuning frequency is up-converted by
readout photons to cause spurious qubit state transitions, thus limiting the
nondemolition character of the readout. Furthermore, we use the qubit
transition rate as a tool to extract an equivalent flux noise spectral density
at f ~ 1 GHz and find agreement with values extrapolated from a
fit to the measured flux noise spectral density below 1 Hz.Comment: 5 pages, 4 figures. Final journal versio
- …