12,227 research outputs found
Measurement of Holmium Rydberg series through MOT depletion spectroscopy
We report measurements of the absolute excitation frequencies of Ho
and odd-parity Rydberg series. The states are
detected through depletion of a magneto-optical trap via a two-photon
excitation scheme. Measurements of 162 Rydberg levels in the range
yield quantum defects well described by the Rydberg-Ritz formula. We observe a
strong perturbation in the series around due to an unidentified
interloper at 48515.47(4) cm. From the series convergence, we determine
the first ionization potential cm, which is
three orders of magnitude more accurate than previous work. This work
represents the first time such spectroscopy has been done in Holmium and is an
important step towards using Ho atoms for collective encoding of a quantum
register.Comment: 6 figure
Single Atom Imaging with an sCMOS camera
Single atom imaging requires discrimination of weak photon count events above
background and has typically been performed using either EMCCD cameras,
photomultiplier tubes or single photon counting modules. sCMOS provides a cost
effective and highly scalable alternative to other single atom imaging
technologies, offering fast readout and larger sensor dimensions. We
demonstrate single atom resolved imaging of two site-addressable single atom
traps separated by 10~m using an sCMOS camera, offering a competitive
signal-to-noise ratio at intermediate count rates to allow high fidelity
readout discrimination (error ) and sub-m spatial resolution for
applications in quantum technologies.Comment: 4 pages, 4 figure
Safety, the Preface Paradox and Possible Worlds Semantics
This paper contains an argument to the effect that possible worlds semantics renders
semantic knowledge impossible, no matter what ontological interpretation is given
to possible worlds. The essential contention made is that possible worlds semantic
knowledge is unsafe and this is shown by a parallel with the preface paradox
Precis of epistemic angst:Book Symposium: Duncan Pritchard, Epistemic Angst (Princeton University Press, 2015, xiii + 236 pages)
ABSTRACT This book symposium features three critical pieces dealing with Duncan Pritchard's book, 'Epistemic Angst'; the symposium also contains Pritchard's replies to his critics
Hybrid Atom--Photon Quantum Gate in a Superconducting Microwave Resonator
We propose a novel hybrid quantum gate between an atom and a microwave photon
in a superconducting coplanar waveguide cavity by exploiting the strong
resonant microwave coupling between adjacent Rydberg states. Using
experimentally achievable parameters gate fidelities are possible on
sub-s timescales for waveguide temperatures below 40 mK. This provides a
mechanism for generating entanglement between two disparate quantum systems and
represents an important step in the creation of a hybrid quantum interface
applicable for both quantum simulation and quantum information processing.Comment: 4 pages, 4 figure
Museum DNA reveals the demographic history of the endangered Seychelles warbler
The importance of evolutionary conservation â how understanding evolutionary forces can help guide conservation decisions â is widely recognized. However, the historical demography of many endangered species is unknown, despite the fact that this can have important implications for contemporary ecological processes and for extinction risk. Here, we reconstruct the population history of the Seychelles warbler (Acrocephalus sechellensis) â an ecological model species. By the 1960s, this species was on the brink of extinction, but its previous history is unknown. We used DNA samples from contemporary and museum specimens spanning 140 years to reconstruct bottleneck history. We found a 25% reduction in genetic diversity between museum and contemporary populations, and strong genetic structure. Simulations indicate that the Seychelles warbler was bottlenecked from a large population, with an ancestral Ne of several thousands falling to <50 within the last century. Such a rapid decline, due to anthropogenic factors, has important implications for extinction risk in the Seychelles warbler, and our results will inform conservation practices. Reconstructing the population history of this species also allows us to better understand patterns of genetic diversity, inbreeding and promiscuity in the contemporary populations. Our approaches can be applied across species to test ecological hypotheses and inform conservation
Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface
We describe the design and characterization of superconducting coplanar
waveguide cavities tailored to facilitate strong coupling between
superconducting quantum circuits and single trapped Rydberg atoms. For initial
superconductor-atom experiments at 4.2 K, we show that resonator quality
factors above can be readily achieved. Furthermore, we demonstrate that
the incorporation of thick-film copper electrodes at a voltage antinode of the
resonator provides a route to enhance the zero-point electric fields of the
resonator in a trapping region that is 40 m above the chip surface,
thereby minimizing chip heating from scattered trap light. The combination of
high resonator quality factor and strong electric dipole coupling between the
resonator and the atom should make it possible to achieve the strong coupling
limit of cavity quantum electrodynamics with this system.Comment: 4 pages, 4 figure
Demonstration of an inductively coupled ring trap for cold atoms
We report the first demonstration of an inductively coupled magnetic ring trap for cold atoms. A uniform, ac magnetic field is used to induce current in a copper ring, which creates an opposing magnetic field that is time-averaged to produce a smooth cylindrically symmetric ring trap of radius 5 mm. We use a laser-cooled atomic sample to characterize the loading efficiency and adiabaticity of the magnetic potential, achieving a vacuum-limited lifetime in the trap. This technique is suitable for creating scalable toroidal waveguides for applications in matter-wave interferometry, offering long interaction times and large enclosed areas
Double-impulse magnetic focusing of launched cold atoms.
We have theoretically investigated three-dimensional focusing of a launched cloud of cold atoms using a pair of magnetic lens pulses (the alternate-gradient method). Individual lenses focus radially and defocus axially or vice versa. The performance of the two possible pulse sequences are compared and found to be ideal for loading both 'pancake' and 'sausage' shaped magnetic/optical microtraps. It is shown that focusing aberrations are considerably smaller for double-impulse magnetic lenses compared to single-impulse magnetic lenses. An analysis of clouds focused by the double-impulse technique is presented
- âŠ