70 research outputs found
Time-Averaged Adiabatic Potentials: Versatile traps and waveguides for ultracold quantum gases
We demonstrate a novel class of trapping potentials, time-averaged adiabatic
potentials (TAAP) which allows the generation of a large variety of traps and
waveguides for ultracold atoms. Multiple traps can be coupled through
controllable tunneling barriers or merged altogether. We present analytical
expressions for pancake-, cigar-, and ring- shaped traps. The ring-geometry is
of particular interest for guided matter-wave interferometry as it provides a
perfectly smooth waveguide of controllable diameter, and thus a tunable
sensitivity of the interferometer.Comment: 5 pages, 3 figure
Monolithic atom interferometry
Atom and, more recently, molecule interferometers are used in fundamental
research and industrial applications. Most atom interferometers rely on
gratings made from laser beams, which can provide high precision but cannot
reach very short wavelengths and require complex laser systems to function.
Contrary to this, simple monolithic interferometers cut from single crystals
offer (sub) nano-meter wavelengths with an extreme level of stability and
robustness. Such devices have been conceived and demonstrated several decades
ago for neutrons and electrons. Here, we propose a monolithic design for a
thermal-beam molecule interferometer based on (quantum) reflection. We show, as
an example, how a reflective, monolithic interferometer (Mach-Zehnder type) can
be realised for a helium beam using Si(111)-H(1x1) surfaces, which have
previously been demonstrated to act as very robust and stable diffractive
mirrors for neutral helium atoms
Frequency tuning of the whispering gallery modes of silica microspheres for CQED and spectroscopy
We have tuned the whispering gallery modes of a fused silica microresonator
over nearly 1 nm at 800 nm, i.e. over 0.5 FSR or 10^6 linewidths of the
resonator. This has been achieved by a new method based on the stretching of a
two-stem microsphere. The devices described below will permit new Cavity-QED
experiments with this high-Q optical resonator when it is desirable to optimize
its coupling to emitters with given transition frequencies. The tuning
capability demonstrated here is compatible with both UHV and low temperature
operation, which should be useful for future experiments with laser cooled
atoms or single quantum dots.Comment: ReVTeX, 4 pages, 3 figure
Hypersonic Bose–Einstein condensates in accelerator rings
© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Some of the most sensitive and precise measurements—for example, of inertia1, gravity2 and rotation3—are based on matter-wave interferometry with free-falling atomic clouds. To achieve very high sensitivities, the interrogation time has to be very long, and consequently the experimental apparatus needs to be very tall (in some cases reaching ten or even one hundred metres) or the experiments must be performed in microgravity in space4–7. Cancelling gravitational acceleration (for example, in atomtronic circuits8,9 and matter-wave guides10) is expected to result in compact devices with extended interrogation times and therefore increased sensitivity. Here we demonstrate smooth and controllable matter-wave guides by transporting Bose–Einstein condensates (BECs) over macroscopic distances. We use a neutral-atom accelerator ring to bring BECs to very high speeds (16 times their sound velocity) and transport them in a magnetic matter-wave guide for 15 centimetres while fully preserving their internal coherence. The resulting high angular momentum of more than 40,000ħ per atom (where ħ is the reduced Planck constant) gives access to the higher Landau levels of quantum Hall states, and the hypersonic velocitiesachieved, combined with our ability to control potentials with picokelvin precision, will facilitate the study of superfluidity and give rise to tunnelling and a large range oftransport regimes of ultracold atoms11–13. Coherent matter-wave guides are expected to enable interaction times of several seconds in highly compact devices and lead to portable guided-atom interferometers for applications such as inertial navigation and gravity mapping
Towards rotation sensing with a single atomic clock
We discuss a scheme to implement a gyroscopic atom sensor with magnetically trapped ultra-cold atoms. Unlike standard light or matter wave Sagnac interferometers no free wave propagation is used. Interferometer operation is controlled only with static, radio-frequency and microwave magnetic fields, which removes the need for interferometric stability of optical laser beams. Due to the confinement of atoms, the scheme may allow the construction of small scale portable sensors. We discuss the main elements of the scheme and report on recent results and efforts towards its experimental realization
Radiation-induced oscillatory magnetoresistance as a sensitive probe of the zero-field spin splitting in high mobility GaAs/AlGaAs devices
We suggest an approach for characterizing the zero-field spin splitting of
high mobility two-dimensional electron systems, when beats are not readily
observable in the Shubnikov-de Haas effect. The zero-field spin splitting and
the effective magnetic field seen in the reference frame of the electron is
evaluated from a quantitative study of beats observed in radiation-induced
magnetoresistance oscillations.Comment: 4 pages, 4 color figure
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