Tag Archives: BEC1

Our latest paper: Decoherence-free radiofrequency dressed subspaces in online

Decoherence-free radiofrequency dressed subspaces

G.A. Sinuco-LeonH. MasS. PandeyG. VasilakisB.M. GarrawayW. von Klitzing

We study the spectral signatures and coherence properties of radiofrequency dressed hyperfine Zeeman sub-levels of 87Rb. Experimentally, we engineer combinations of static and RF magnetic fields to modify the response of the atomic spin states to environmental magnetic field noise. We demonstrate analytically and experimentally the existence of ‘magic’ dressing conditions where decoherence due to electromagnetic field noise is strongly suppressed. Building upon this result, we propose a bi-chromatic dressing configuration that reduces the global sensitivity of the atomic ground states to low-frequency noise, and enables the simultaneous protection of multiple transitions between the two ground hyperfine manifolds of atomic alkali species. Our methods produce protected transitions between any pair of hyperfine sub-levels at arbitrary (low) DC-magnetic fields.

Now on arXive !n

Saurabh will defend his thesis 12/7/2019

Πρόσκληση σε Δημόσια Παρουσίαση της Διδακτορικής Διατριβής του

κ. Saurabh Pandey

(Σύμφωνα με το άρθρο 41 του Ν. 4485/2017)

Την Παρασκευή 12 Ιουλίου 2019 και ώρα 10:00 στην αίθουσα Τηλεεκπαίδευσης στο κτήριο Τμήματος Μαθηματικών και Εφαρμοσμένων Μαθηματικών, Πανεπιστημίου Κρήτης, θα γίνει η δημόσια παρουσίαση και υποστήριξη της Διδακτορικής Διατριβής του υποψήφιου διδάκτορα του Τμήματος Επιστήμης και Τεχνολογίας Υλικών κ. Saurabh Pandey με θέμα:

«Guided Matter-Wave Interferometry»


Atom interferometry is an extremely sensitive and accurate means of measuring time, gravity, rotation, acceleration, magnetic gradients, and even fundamental physical constants. In particular for rotation sensing, these atomic systems are 10 billion times more sensitive than the optical gyroscopes, for an equal area of the interferometer loop. For practical applications such as satellite-free navigation, the ultracold atom based gyroscopes have to become portable and compact, without compromising their sensitivity.  This can be achieved by trapping and manipulation of ultracold atoms in smooth, area-enclosing waveguides. A major challenge, so far, has been the lack of ability to guide the trapped atomic wave-packets over long distances at relatively high speeds.

I will present excitation-free transport of Bose-Einstein condensates (BECs) at hypersonic speeds in magnetic time-averaged adiabatic potential (TAAP) rings traps. For the first time, matter-waves are transported for a record distance of 40 cm at hypersonic speeds without detecting any extra excitation when compared to the static case. The extreme smoothness of TAAP rings is demonstrated via the propagation of ultracold 87Rb atoms in ring waveguides. In addition, I studied atom optics with moving BECs in flat ring waveguides, to enable long distance guiding, and ultralow temperatures of the trapped atoms. I implemented an optimal cooling technique to achieve compact BEC guiding for seconds, and the effective BEC interaction energy was lowered by a factor of 30. These demonstrations provide a new platform to realize highly sensitive, miniaturized cold-atom-based gyroscopes, and investigate fundamental questions.

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)