arXiv subjects

Michal Zawada

Publications and source records attributed to Michal Zawada.

9 recordsLinked to original sources

arXiv2024

CIRCUS: an autonomous control system for antimatter, atomic and quantum physics experiments

A powerful and robust control system is a crucial, often neglected, pillar of any modern, complex physics experiment that requires the management of a multitude of different devices and their precise time synchronisation. The AEgIS collaboration presents CIRCUS, a novel, autonomous control system optimised for time-critical experiments such as those at CERN's Antiproton Decelerator and, more broadly, in atomic and quantum physics research. Its setup is based on Sinara/ARTIQ and TALOS, integrating the ALPACA analysis pipeline, the last two developed entirely in AEgIS. It is suitable for strict synchronicity requirements and repeatable, automated operation of experiments, culminating in autonomous parameter optimisation via feedback from real-time data analysis. CIRCUS has been successfully deployed and tested in AEgIS; being experiment-agnostic and released open-source, other experiments can leverage its capabilities.

quant-ph↗

arXiv2017

Dual Hg-Rb magneto-optical trap

We present a two-species laser cooling apparatus capable of simultaneously collecting Rb and Hg atomic gases into a magneto-optical trap (MOT). The atomic sources, laser system, and vacuum set-up are described. While there is a loss of Rb atoms in the MOT due to photoionization by the Hg cooling laser, we show that it does not prevent simultaneous trapping of Rb and Hg. We also demonstrate interspecies collision-induced losses in the ${}^{87}$Rb-${}^{202}$Hg system.

physics.atom-ph↗

arXiv2016

Searching for topological defect dark matter with optical atomic clocks

The total mass density of the Universe appears to be dominated by dark matter. However, beyond its gravitational interactions at the galactic scale, little is known about its nature. Extensions of the quantum electrodynamics Lagrangian with dark-matter coupling terms may result in changes to Standard Model parameters. Recently, it was proposed that a network of atomic clocks could be used to search for transient signals of a hypothetical dark matter in the form of stable topological defects. The clocks become desynchronized when a dark-matter object sweeps through the network. This pioneering approach, which is applicable only for distant clocks, is limited by the quality of the fibre links. Here, we present an alternative experimental approach that is applicable to both closely spaced and distant optical atomic clocks and benefits from their individual susceptibilities to dark matter, hence not requiring fibre links. We explore a new dimension of astrophysical observations by constraining the strength of atomic coupling to the hypothetical dark-matter cosmic objects. Our experimental constraint exceeds the previous limits; in fact, it not only reaches the ultimate level expected to be achievable with a constellation of GPS atomic clocks but also has a large potential for improvement.

physics.atom-ph↗

arXiv2015

Absolute measurement of the ${}^{1}S_{0}$ - ${}^{3}P_{0}$ clock transition in neutral ${}^{88}$Sr over the 330 km-long stabilized fibre optic link

We report a stability below $7\times 10{}^{-17}$ of two independent optical lattice clocks operating with bosonic ${}^{88}$Sr isotope. The value (429228066418008.3(1.9)${}_{syst}$(0.9)${}_{stat}$~Hz) of the absolute frequency of the ${}^{1}S_{0}$ - ${}^{3}P_{0}$ transition was measured with an optical frequency comb referenced to the local representation of the UTC by the 330 km-long stabilized fibre optical link. The result was verified by series of measurements on two independent optical lattice clocks and agrees with recommendation of Bureau International des Poids et Mesures.

physics.atom-ph↗

arXiv2013

Absolute Frequency Measurement of Rubidium 5S-7S Two-Photon Transitions

We report the absolute frequency measurements of rubidium 5S-7S two-photon transitions with a cw laser digitally locked to an atomic transition and referenced to an optical frequency comb. The narrow, two-photon transition, 5S-7S (760 nm) insensitive to first order in a magnetic field, is a promising candidate for frequency reference. The performed tests yield the transition frequency with accuracy better than reported previously.

physics.atom-ph↗

arXiv2013

Matter-Wave Interference versus Spontaneous Pattern Formation in Spinor Bose-Einstein Condensate

We describe effects of matter-wave interference of spinor states in the $^{87}$Rb Bose-Einstein condensate. The components of the F=2 manifold are populated by forced Majorana transitions and then fall freely due to gravity in an applied magnetic field. Weak inhomogeneities of the magnetic field, present in the experiment, impose relative velocities onto different $m_F$ components, which show up as interference patterns upon measurement of atomic density distributions with a Stern-Gerlach imaging method. We show that interference effects may appear in experiments even if gradients of the magnetic field components are eliminated but higher order inhomogeneity is present and the duration of the interaction is long enough. In particular, we show that the resulting matter-wave interference patterns can mimic spontaneous pattern formation in the quantum gas.

cond-mat.quant-gas↗

arXiv2011

Observation and cancellation of the dc Stark shift in strontium optical lattice clocks

We report on the observation of a dc Stark frequency shift at the $10^{-13}$ level by comparing two strontium optical lattice clocks. This frequency shift arises from the presence of electric charges trapped on dielectric surfaces placed under vacuum close to the atomic sample. We show that these charges can be eliminated by shining UV light on the dielectric surfaces, and characterize the residual dc Stark frequency shift on the clock transition at the $10^{-18}$ level by applying an external electric field. This study shows that the dc Stark shift can play an important role in the accuracy budget of lattice clocks, and should be duly taken into account.

physics.atom-ph↗

arXiv2011

Lattice Induced Frequency Shifts in Sr Optical Lattice Clocks at the $10^{-17}$ Level

We present a comprehensive study of the frequency shifts associated with the lattice potential for a Sr lattice clock. By comparing two such clocks with a frequency stability reaching $5\times 10^{-17}$ after a one hour integration time, and varying the lattice depth up to $U_0=900 \, E_r$ with $E_r$ being the recoil energy, we evaluate lattice related shifts with an unprecedented accuracy. We put the first experimental upper bound on the recently predicted frequency shift due to the magnetic dipole (M1) and electric quadrupole (E2) interactions. This upper bound is significantly smaller than the theoretical upper limit. We also give a new upper limit on the effect of hyperpolarizability with an improvement by more than one order of magnitude. Finally, we report the first observation of the vector and tensor shifts in a lattice clock. Combining these measurements, we show that all known lattice related perturbation will not affect the clock accuracy down to the $10^{-17}$ level, even for very deep lattices, up to $U_0=150\,E_r$.

physics.atom-ph↗

arXiv2008

Optimal geometry for efficient loading of an optical dipole trap

One important factor which determines efficiency of loading cold atoms into an optical dipole trap from a magneto-optical trap is the distance between the trap centers. By studying this efficiency for various optical trap depths (2--110 mK) we find that for optimum dipole trap loading, longitudinal displacements up to 15 mm are necessary. An explanation for this observation is presented and compared with other work and a simple analytical formula is derived for the optimum distance between the trap centers.

physics.atom-ph↗