Category Archives: BEC 1

Making BECs smile.

Just for fun… BECs can also smile:  This is a BEC loaded from a dipole trap into a TAAP trap and then propagated for some time. The picture is an absorption  image with darker standing for a higher number of atoms.

We are also learning to write  😉 … for example the letter H

An H-shaped thermal cloud of Rb87 atoms (black is more atoms)

And our latest addition …  the number 9

A BEC in a ring-accelerator. We first load a BEC into a dipole trap and then into the ring. We then accelerate the BEC to speeds, where the centripetal confinement is not sufficient to keep the BEC in the storage ring. (white=more atoms)

 

And of course our smiling BEC

A smiling BEC — a reproducible chance event.
(black is more atoms)

Matter-wave interferometers using TAAP rings

New Journal of Physics   18   075014 (2016)

P. Navez, S. Pandey, H. Mas, K. Poulios, T. Fernholz, and W. von Klitzing

doi: 10.1088/1367-2630/18/7/075014

Fig 2

Figure 2. Experimental realisation of a ring-shaped TAAP waveguide (s = 0, d = 0) with rubidium atoms in the ∣2, +2ñ state. The quadrupole gradient is a = 50 G cm−1 with wrf 2p = 2.62 MHz. The measured Rabi frequency is Wrf 2p = 215 kHz. The radius of the ring is R = 570 μm.

Abstract: We present two novel matter-wave Sagnac interferometers based on ring-shaped time-averaged adiabatic potentials, where the atoms are put into a superposition of two different spin states and manipulated independently using elliptically polarized rf-fields. In the first interferometer the atoms are accelerated by spin-state-dependent forces and then travel around the ring in a matter-wave guide. In the second one the atoms are

Figure 6.

Figure 6. Experimental realisation of arbitrary traps with (s 1 0, d 1 0) for the two states ∣2, +2ñ (5 × 105 atoms) and ∣1, -1ñ (3 × 105 atoms) at wrf 2p = 2.62 MHz . The fitted radius is 440 μm and 450 μm respectively. The quadrupole gradient is
a = 55 G cm−1. Note that (a) and (b) are taken with identical experimental conditions and differ only in the state of the atoms. The axis of the circular rf component and the one of the tilted modulation are not orthogonal.

fully trapped during the entire interferometric sequence and are moved around the ring in two spin-state-dep
endent `buckets’. Corrections to the ideal Sagnac phase are investigated for both cases. We experimentally demonstrate the key atom-optical elements of the interferometer such as the independent manipulation of two different spin states in the ring-shaped potentials under identical experimental conditions.

Towards rotation sensing with a single atomic clock

Proc. SPIE   9900   990007-990007-14 (2016)

T. Fernholz, R. Stevenson, M. R. Hush, I. V. Lesanovsky, T. Bishop, F. Gentile, S. Jammi, T. Pyragius, M. G. Bason, H. Mas, S. Pandey, G. Vasilakis, K. Poulios, and W. von Klitzing

http://dx.doi.org/10.1117/12.2229878

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.

One of the possibilities discussed are state dependent TAAPs:

fernholz2016ps-rotating-rings

fernholz2016ps-ring-trap

However also chip scale solutions are discussed.