10 research outputs found
Thermalization near integrability in a dipolar quantum Newton's cradle
Isolated quantum many-body systems with integrable dynamics generically do
not thermalize when taken far from equilibrium. As one perturbs such systems
away from the integrable point, thermalization sets in, but the nature of the
crossover from integrable to thermalizing behavior is an unresolved and
actively discussed question. We explore this question by studying the dynamics
of the momentum distribution function in a dipolar quantum Newton's cradle
consisting of highly magnetic dysprosium atoms. This is accomplished by
creating the first one-dimensional Bose gas with strong magnetic dipole-dipole
interactions. These interactions provide tunability of both the strength of the
integrability-breaking perturbation and the nature of the near-integrable
dynamics. We provide the first experimental evidence that thermalization close
to a strongly interacting integrable point occurs in two steps:
prethermalization followed by near-exponential thermalization. Exact numerical
calculations on a two-rung lattice model yield a similar two-timescale process,
suggesting that this is generic in strongly interacting near-integrable models.
Moreover, the measured thermalization rate is consistent with a parameter-free
theoretical estimate, based on identifying the types of collisions that
dominate thermalization. By providing tunability between regimes of integrable
and nonintegrable dynamics, our work sheds light both on the mechanisms by
which isolated quantum many-body systems thermalize, and on the temporal
structure of the onset of thermalization.Comment: 6 figures, 9 pages main text; 12 appendices with 12 figure
Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data
We present a sample of 59 periodic variables from the Palomar Transient
Factory, selected from published catalogues of white dwarf (WD) candidates. The
variability can likely be attributed to ellipsoidal variation of the tidally
distorted companion induced by the gravity of the primary (WD or hot subdwarf)
or to the reflection of hot emission by a cooler companion. We searched 11311
spectroscopically or photometrically selected WD candidates from three hot
star/WD catalogues, using the Lomb-Scargle periodogram to single out promising
sources. We present period estimates for the candidates, 45 of which were not
previously identified as periodic variables, and find that most have a period
shorter than a few days. Additionally, we discuss the eclipsing systems in our
sample and present spectroscopic data on selected sources
Lithium tantalate electro-optical photonic integrated circuits for high volume manufacturing
Photonic integrated circuits based on Lithium Niobate have demonstrated the
vast capabilities afforded by material with a high Pockels coefficient,
allowing linear and high-speed modulators operating at CMOS voltage levels for
applications ranging from data-center communications and photonic accelerators
for AI. However despite major progress, the industrial adoption of this
technology is compounded by the high cost per wafer. Here we overcome this
challenge and demonstrate a photonic platform that satisfies the dichotomy of
allowing scalable manufacturing at low cost, while at the same time exhibiting
equal, and superior properties to those of Lithium Niobate. We demonstrate that
it is possible to manufacture low loss photonic integrated circuits using
Lithium Tantalate, a material that is already commercially adopted for acoustic
filters in 5G and 6G. We show that LiTaO3 posses equally attractive optical
properties and can be etched with high precision and negligible residues using
DUV lithography, diamond like carbon (DLC) as a hard mask and alkaline wet
etching. Using this approach we demonstrate microresonators with an intrinsic
cavity linewidth of 26.8 MHz, corresponding to a linear loss of 5.6 dB/m and
demonstrate a Mach Zehnder modulator with Vpi L = 4.2 V cm half-wave voltage
length product. In comparison to Lithium Niobate, the photonic integrated
circuits based on LiTaO3 exhibit a much lower birefringence, allowing
high-density circuits and broadband operation over all telecommunication bands
(O to L band), exhibit higher photorefractive damage threshold, and lower
microwave loss tangent. Moreover, we show that the platform supports generation
of soliton microcombs in X-Cut LiTaO3 racetrack microresonator with
electronically detectable repetition rate, i.e. 30.1 GHz.Comment: 8 pages, 4 figure
Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data
We present a sample of 59 periodic variables from the Palomar Transient Factory, selected from published catalogues of white dwarf (WD) candidates. The variability can likely be attributed to ellipsoidal variation of the tidally distorted companion induced by the gravity of the primary (WD or hot subdwarf) or to the reflection of hot emission by a cooler companion. We searched 11â311 spectroscopically or photometrically selected WD candidates from three hot star/WD catalogues, using the LombâScargle periodogram to single out promising sources. We present period estimates for the candidates, 45 of which were not previously identified as periodic variables, and find that most have a period shorter than a few days. Additionally, we discuss the eclipsing systems in our sample and present spectroscopic data on selected sources
Search for a fermiophobic Higgs boson in collisions at TeV
Combined results are reported from searches for a fermiophobic Higgs boson in
the gamma-gamma, WW, and ZZ decay modes in proton-proton collisions at sqrt(s)
= 7 TeV. The explored Higgs boson mass range is 110-300 GeV. The data sample
corresponds to an integrated luminosity of 4.9-5.1 inverse femtobarns. A
fermiophobic Higgs boson is excluded at 95% confidence level in the mass range
110-194 GeV, and at 99% confidence level in the mass ranges 110-124.5 GeV,
127-147.5 GeV, and 155-180 GeV.Comment: Submitted to the Journal of High Energy Physic