Dispersion management using betatron resonances in an ultracold-atom storage ring

Hypersonic Bose-Einstein condensates in accelerator rings

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 space^4-7. Cancelling gravitational acceleration (for example, in atomtronic circuits^8,9 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 velocities achieved, 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 of transport regimes of ultracold atoms^11-13. 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.

Superfluid helium quantum interference devices: physics and applications

We present an overview of recent developments related to superfluid helium quantum interference devices (SHeQUIDs). We discuss the physics of two reservoirs of superfluid helium coupled together and describe the quantum oscillations that result from varying the coupling strength. We explain the principles behind SHeQUIDs that can be built based on these oscillations and review some techniques and applications.

Superfluid quantum interference in multiple-turn reciprocal geometry

We report the observation of superfluid quantum interference in a compact, large-area matter-wave interferometer consisting of a multiple-turn interfering path in reciprocal geometry. Utilizing the Sagnac effect from Earth's rotation in conjunction with a phase shifter made of superfluid heat current, we demonstrate that such a scheme can be extended for sensitive rotation sensing as well as for general interferometry.

Demonstration of an area-enclosing guided-atom interferometer for rotation sensing

We demonstrate area-enclosing atom interferometry based on a moving guide. Light pulses along the free-propagation direction of a magnetic guide are applied to split and recombine the confined atomic matter-wave, while the atoms are translated back and forth along a second direction in 50 ms. The interferometer is estimated to resolve 10 times the earth rotation rate per interferometry cycle. We demonstrate a "folded figure 8" interfering configuration for creating a compact, large-area atom gyroscope with multiple-turn interfering paths.

Probing the quantum state of a guided atom laser pulse

We describe bichromatic superradiant pump-probe spectroscopy as a tomographic probe of the Wigner function of a dispersing particle beam. We employed this technique to characterize the quantum state of an ultracold atomic beam, derived from a 87Rb Bose-Einstein condensate, as it propagated in a 2.5 mm diameter circular waveguide. Our measurements place an upper bound on the longitudinal phase space area occupied by the 3 x 10(5) atom beam of 9(1)Planck's constant and a lower bound on the coherence length of L>or=13(1) microm. These results are consistent with full quantum degeneracy after multiple orbits around the waveguide.