scholarly journals Precision engineering for ultra-cold atoms and space experiments

2021 ◽  
Author(s):  
Ιωάννης Δρουγκάκης
Keyword(s):  
Cold Atoms ◽  
Precision Engineering ◽  
Space Experiments ◽  
Bose Einstein

Οι υπερ-ψυχρές τεχνολογίες ατόμων υπόσχονται σημαντικές βελτιώσεις στους τομείς της ανίχνευσης, της επικοινωνίας, της κβαντικής προσομοίωσης και του υπολογισμού. Για να αξιοποιηθούν πλήρως οι δυνατότητές τους, πρέπει να αναπτυχθούν πολλές νέες τεχνολογίες. Σε αυτή τη διατριβή επικεντρώνομαι σε τρεις από αυτές: την μηχανική ακρίβειας των κυματοδηγών, την μηχανική ακριβείας της κατάστασης εισόδου του αισθητήρα και τις εξαιρετικά σταθερές και στιβαρές τεχνολογίες για διαστημικές αποστολές. Αυτές οι τρεις κύριες προκλήσεις του πεδίου διερευνώνται σε αυτήν την εργασία. Αρχικά, διερευνώ τα όρια της χωρίς διέγερση μεταφοράς συμπυκνωμάτων Bose-Einstein (BECs) και υπερ-ψυχρών ατομικών νεφών σε κυματοδηγούς μαγνητικού πεδίου (TAAP) με σχήμα δακτυλίου εισάγοντας τεχνητά εμπόδια. Παρατηρείται μια ευρεία περιοχή όπου δεν υπάρχει διέγερση μέχρι την τιμή ενός κατωφλίου, όπου παρατηρείται απότομη αύξηση της διέγερσης του ατομικού νέφους. Παρουσιάζω επίσης μια ακριβή και απλή μέθοδο ανίχνευσης, με μόνο σφάλμα 1% στη μέτρηση του αριθμού των ατόμων. Αυτό αποτελεί βελτίωση περίπου 10 φορές στην ακρίβεια της πειραματικής μας ακολουθίας. Η μέθοδος έχει τη δυνατότητα να εφαρμοστεί ως ελάχιστα καταστρεπτική τεχνική μέτρησης για την κβαντική κατάσταση και τη θερμοκρασία του υπερ-ψυχρού νέφους. Τέλος, αναπτύχθηκε μια συμβατή με το διάστημα σύζευξη οπτικών ινών. Επιτεύχθηκε υψηλή απόδοση σύζευξης της τάξης του 94% και διακυμάνσεις μικρότερες από 1% παρουσία διακυμάνσεων στην θερμοκρασία και κραδασμών. Αυτές οι επιδείξεις ανοίγουν το δρόμο προς την πραγματοποίηση πρακτικών συσκευών που βασίζονται σε υπέρψυχρα νέφη. Στα πλαίσια της εργασίας σχεδιάστηκαν και δημιουργήθηκαν προσαρμοσμένες ηλεκτρονικές διατάξεις και λογισμικό.

scholarly journals Effective Potential for Ultracold Atoms at the Zero Crossing of a Feshbach Resonance

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
N. T. Zinner
Keyword(s):  
Effective Potential ◽  
Feshbach Resonance ◽  
Cold Atoms ◽  
Particle Number ◽  
Scattering Length ◽  
Order Effect ◽  
Effective Range ◽  
Effective Range Expansion ◽  
Zero Crossing ◽  
Bose Einstein

We consider finite-range effects when the scattering length goes to zero near a magnetically controlled Feshbach resonance. The traditional effective-range expansion is badly behaved at this point, and we therefore introduce an effective potential that reproduces the full T-matrix. To lowest order the effective potential goes as momentum squared times a factor that is well defined as the scattering length goes to zero. The potential turns out to be proportional to the background scattering length squared times the background effective range for the resonance. We proceed to estimate the applicability and relative importance of this potential for Bose-Einstein condensates and for two-component Fermi gases where the attractive nature of the effective potential can lead to collapse above a critical particle number or induce instability toward pairing and superfluidity. For broad Feshbach resonances the higher order effect is completely negligible. However, for narrow resonances in tightly confined samples signatures might be experimentally accessible. This could be relevant for suboptical wavelength microstructured traps at the interface of cold atoms and solid-state surfaces.

scholarly journals Theory of cold atoms: Bose–Einstein statistics

Laser Physics ◽  
2016 ◽  
Vol 26 (6) ◽  
pp. 062001 ◽  
Author(s):  
V I Yukalov
Keyword(s):  
Cold Atoms ◽  
Bose Einstein

scholarly journals Fluctuations and temperature effects in bose-einstein condensation

2018 ◽  
Vol 61 ◽  
pp. 55-67
Author(s):  
Anne de Bouard ◽  
Arnaud Debussche ◽  
Reika Fukuizumi ◽  
Romain Poncet
Keyword(s):  
Temperature Effects ◽  
Cold Atoms ◽  
Numerical Results ◽  
Theoretical Physics ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Physics Community ◽  
Bose Einstein

The modeling of cold atoms systems has known an increasing interest in the theoretical physics community, after the first experimental realizations of Bose Einstein condensates, some twenty years ago. We here review some analytical and numerical results concerning the influence of fluctua-tions, either arising from fluctuations of the confining parameters, or due to temperature effects, in the models describing the dynamics of such condensates.

INTERACTIONS OF ELECTROMAGNETIC RADIATION WITH BOSE–EINSTEIN CONDENSATES: MANIPULATING ULTRA–COLD ATOMS WITH LIGHT

2013 ◽  
Vol 27 (06) ◽  
pp. 1330003 ◽  
Author(s):  
FEDERICA CATTANI ◽  
ARKADY KIM ◽  
MIETEK LISAK ◽  
DAN ANDERSON
Keyword(s):  
Electromagnetic Radiation ◽  
Local Field ◽  
Cold Atoms ◽  
Laser Light ◽  
Field Effects ◽  
Quantum Models ◽  
Bose Einstein

A review of models describing the interactions of ultra-cold atoms and laser light is given. Both semi-classical and fully quantum models are presented with particular attention given to the introduction of local field effects. Some possible effects of self-localization and guiding, consequences of such interactions, are discussed.

scholarly journals Fabrication of micro-magnetic traps for cold neutral atoms

2003 ◽  
Vol 3 (5) ◽  
pp. 450-464
Author(s):  
B. Lev
Keyword(s):  
Cold Atoms ◽  
Quantum Information Processing ◽  
Clean Room ◽  
Neutral Atoms ◽  
Magnetic Traps ◽  
Precise Control ◽  
Flat Substrate ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Bose Einstein

Many proposals for quantum information processing require precise control over the motion of neutral atoms, as in the manipulation of coherent matter waves or the confinement and localization of individual atoms. Patterns of micron-sized wires, fabricated lithographically on a flat substrate, can conveniently produce large magnetic-field gradients and curvatures to trap cold atoms and to facilitate the production of Bose-Einstein condensates. The intent of this paper is to provide the researcher who has access to a standard clean-room enough information to design and fabricate such devices.

NEW FORMS OF QUANTUM MATTER NEAR ABSOLUTE ZERO TEMPERATURE

2007 ◽  
Vol 16 (12b) ◽  
pp. 2413-2419
Author(s):  
WOLFGANG KETTERLE
Keyword(s):  
Atomic Physics ◽  
Cold Atoms ◽  
Einstein Condensation ◽  
Many Body ◽  
New Techniques ◽  
Quantum Reflection ◽  
Fermionic Atoms ◽  
Interacting Systems ◽  
Bose Einstein ◽  
Physical Phenomena

In my talk at the workshop on fundamental physics in space I described the nanokelvin revolution which has taken place in atomic physics. Nanokelvin temperatures have given us access to new physical phenomena including Bose–Einstein condensation, quantum reflection, and fermionic superfluidity in a gas. They also enabled new techniques of preparing and manipulating cold atoms. At low temperatures, only very weak forces are needed to control the motion of atoms. This gave rise to the development of miniaturized setups including atom chips. In Earth-based experiments, gravitational forces are dominant unless they are compensated by optical and magnetic forces. The following text describes the work which I used to illustrate the nanokelvin revolution in atomic physics. Strongest emphasis is given to superfluidity in fermionic atoms. This is a prime example of how ultracold atoms are used to create well-controlled strongly interacting systems and obtain new insight into many-body physics.

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