15 research outputs found
Analytical model for ring heater thermal compensation in the Advanced Laser Interferometer Gravitational-wave Observatory
Advanced laser interferometer gravitational-wave detectors use high laser power to achieve design sensitivity. A small part of this power is absorbed in the interferometer cavity mirrors where it creates thermal lenses, causing aberrations in the main laser beam that must be minimized by the actuation of “ring heaters,” which are additional heater elements that are aimed to reduce the temperature gradients in the mirrors. In this article we derive the first, to the best of our knowledge, analytical model of the temperature field generated by an ideal ring heater. We express the resulting optical aberration contribution to the main laser beam in this axisymmetric case. Used in conjunction with wavefront measurements, our model provides a more complete understanding of the thermal state of the cavity mirrors and will allow a more efficient use of the ring heaters in the Advanced Laser Interferometer Gravitational-wave Observatory
Landau-Forbidden Quantum Criticality in Rydberg Quantum Simulators
The Landau-Ginzburg-Wilson theory of phase transitions precludes a continuous
transition between two phases that spontaneously break distinct symmetries.
However, quantum mechanical effects can intertwine the symmetries, giving rise
to an exotic phenomenon called deconfined quantum criticality (DQC). In this
work, we study the ground state phase diagram of a one-dimensional array of
individually trapped neutral atoms interacting strongly via Rydberg states, and
demonstrate through extensive numerical simulations that it hosts a variety of
symmetry-breaking phases and their transitions including DQC. We show how an
enlarged, emergent continuous symmetry arises at the DQCs, which can be
experimentally observed in the joint distribution of two distinct order
parameters, obtained within measurement snapshots in the standard computational
basis. Our findings highlight quantum simulators of Rydberg atoms not only as
promising platforms to experimentally realize such exotic phenomena, but also
as unique ones allowing access to physical properties not obtainable in
traditional experiments
Thermal modelling of Advanced LIGO test masses
High-reflectivity fused silica mirrors are at the epicentre of current
advanced gravitational wave detectors. In these detectors, the mirrors interact
with high power laser beams. As a result of finite absorption in the high
reflectivity coatings the mirrors suffer from a variety of thermal effects that
impact on the detectors performance. We propose a model of the Advanced LIGO
mirrors that introduces an empirical term to account for the radiative heat
transfer between the mirror and its surroundings. The mechanical mode frequency
is used as a probe for the overall temperature of the mirror. The thermal
transient after power build-up in the optical cavities is used to refine and
test the model. The model provides a coating absorption estimate of 1.5 to 2.0
ppm and estimates that 0.3 to 1.3 ppm of the circulating light is scattered on
to the ring heater.Comment: 14 pages, 9 figure
Machine-learning-accelerated Bose-Einstein condensation
Machine learning is emerging as a technology that can enhance physics
experiment execution and data analysis. Here, we apply machine learning to
accelerate the production of a Bose-Einstein condensate (BEC) of
atoms by Bayesian optimization of up to 55 control
parameters. This approach enables us to prepare BECs of
optically trapped atoms from a room-temperature gas in 575
ms. The algorithm achieves the fast BEC preparation by applying highly
efficient Raman cooling to near quantum degeneracy, followed by a brief final
evaporation. We anticipate that many other physics experiments with complex
nonlinear system dynamics can be significantly enhanced by a similar
machine-learning approach.Comment: 9 pages, 5 figures + supplemental materia
Improving ATLAS Jet Measurements and Searches with Particle Information
With the LHC running at record collision energies, the ATLAS detector may reveal new physics including particles decaying hadronically into jets. Measurements involving jets are often limited by the jet energy scale uncertainty associated with the calibration of the detector response to jets in the hadronic calorimeters. In this article we examine the jet energy response dependence upon the fraction of jet energy contained in charged versus neutral particles by running the multijet balance with particle flow jets on a series of charged fraction cuts using both Monte Carlo and data jet samples. We discuss how the results can contribute to a reduction of the jet energy uncertainty for high energy jets where the uncertainty is estimated with the single particle propagation technique
Fault-tolerant connection of error-corrected qubits with noisy links
One of the most promising routes toward scalable quantum computing is a modular approach. We show that distinct surface code patches can be connected in a fault-tolerant manner even in the presence of substantial noise along their connecting interface. We quantify analytically and numerically the combined effect of errors across the interface and bulk. We show that the system can tolerate 14 times higher noise at the interface compared to the bulk, with only a small effect on the code’s threshold and subthreshold behavior, reaching threshold with ~1% bulk errors and ~10% interface errors. This implies that fault-tolerant scaling of error-corrected modular devices is within reach using existing technology.</p
Direct Laser Cooling to Bose-Einstein Condensation in a Dipole Trap
© 2019 American Physical Society. We present a method for producing three-dimensional Bose-Einstein condensates using only laser cooling. The phase transition to condensation is crossed with 2.5×104 Rb87 atoms at a temperature of Tc=0.6 μK after 1.4 s of cooling. Atoms are trapped in a crossed optical dipole trap and cooled using Raman cooling with far-off-resonant optical pumping light to reduce atom loss and heating. The achieved temperatures are well below the effective recoil temperature. We find that during the final cooling stage at atomic densities above 1014 cm-3, careful tuning of trap depth and optical-pumping rate is necessary to evade heating and loss mechanisms. The method may enable the fast production of quantum degenerate gases in a variety of systems including fermions