Seminarium Optyczne
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2016-11-10 (Czwartek)
Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:15 
Professor Ken Baldwin (Australian National University, Canberra, Australian Capital Territory 0200, Australia)Ghost Imaging with Atoms
Ghost imaging is a technique - first realized in quantum optics - that uses the cross-correlation between particles in two separate beams, one of which passes through the object to a bucket (single-pixel) detector, while the second is measured by a high spatial resolution (multi-pixel) detector but never interacts with the object. Neither detector can reconstruct the image independently. Here we report on the first realisation of ghost imaging of a macroscopic object using massive particles [1]. In our experiment, the two beams are formed by correlated pairs [2] of ultracold metastable helium atoms [3] originating from two colliding Bose-Einstein condensates (BECs). We use higher-order Kapitza-Dirac scattering to generate the large number of correlated atom pairs required, enabling the creation of a ghost image with good visibility and sub-millimetre resolution.References:1. “Ghost Imaging with Atoms”, R.I. Khakimov, B.M. Henson, D.K. Shin, S.S. Hodgman, R.G. Dall, K.G.H. Baldwin and A.G. Truscott (2016). http://arxiv.org/abs/1607.022402. “Direct measurement of long-range third-order coherence in Bose-Einstein condensates”, S. S. Hodgman, R. G. Dall, A. G. Manning, K. G. H. Baldwin, and A. G. Truscott, Science 331, 1046 (2011).http://science.sciencemag.org/content/331/6020/1046.full.pdf3. “Cold and trapped metastable noble gases”, W. Vassen, C. Cohen-Tannoudji, M. Leduc, D. Boiron, C. I. Westbrook, A. Truscott, K. Baldwin, G. Birkl, P. Cancio, and M. Trippenbach, Reviews of Modern Physics 84, 175 (2012). http://journals.aps.org/rmp/abstract/10.1103/RevModPhys.84.175
Ghost imaging is a technique - first realized in quantum optics - that uses the cross-correlation between particles in two separate beams, one of which passes through the object to a bucket (single-pixel) detector, while the second is measured by a high spatial resolution (multi-pixel) detector but never interacts with the object. Neither detector can reconstruct the image independently. Here we report on the first realisation of ghost imaging of a macroscopic object using massive particles [1]. In our experiment, the two beams are formed by correlated pairs [2] of ultracold metastable helium atoms [3] originating from two colliding Bose-Einstein condensates (BECs). We use higher-order Kapitza-Dirac scattering to generate the large number of correlated atom pairs required, enabling the creation of a ghost image with good visibility and sub-millimetre resolution.References:1. “Ghost Imaging with Atoms”, R.I. Khakimov, B.M. Henson, D.K. Shin, S.S. Hodgman, R.G. Dall, K.G.H. Baldwin and A.G. Truscott (2016). http://arxiv.org/abs/1607.022402. “Direct measurement of long-range third-order coherence in Bose-Einstein condensates”, S. S. Hodgman, R. G. Dall, A. G. Manning, K. G. H. Baldwin, and A. G. Truscott, Science 331, 1046 (2011).http://science.sciencemag.org/content/331/6020/1046.full.pdf3. “Cold and trapped metastable noble gases”, W. Vassen, C. Cohen-Tannoudji, M. Leduc, D. Boiron, C. I. Westbrook, A. Truscott, K. Baldwin, G. Birkl, P. Cancio, and M. Trippenbach, Reviews of Modern Physics 84, 175 (2012). http://journals.aps.org/rmp/abstract/10.1103/RevModPhys.84.175
2016-11-03 (Czwartek)
Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:15
dr Tomasz Wąsowicz (Politechnika Gdańska)Fotodysocjacja cząsteczek heterocyklicznych
2016-10-27 (Czwartek)
Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:15
dr inż. Łukasz Kłosowski (UMK Toruń)Wytwarzanie i chłodzenie jonów molekularnych w pułapkach
2016-10-20 (Czwartek)
Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:15
prof. Kazimierz Rzążewski (CFT PAN)O dwu - składnikowym gazie fermionowym
2016-10-06 (Czwartek)
Zapraszamy do sali 1.40, ul. Pasteura 5 o godzinie 09:15
dr Krzysztof Pawłowski (Centrum Fizyki Teoretycznej PAN)Cavity-feedback scheme: Entanglement and decoherence of atoms in an optical cavity
We theoretically investigate the entangled states of an atomic ensemblethat can be obtained via cavity-feedback, varying the atom-lightcoupling from weak to strong, and including a systematic treatment ofdecoherence. In the strong coupling regime for small atomic ensembles, the system is driven by cavity losses into a long-lived, highly-entangled many-body state that we charaterize analytically. In the weak coupling regime for large ensembles, we and analytically the maximum spin squeezing that can be achieved by optimizing both the coupling and the atom number. This squeezing is fundamentally limited by spontaneous emission to a constant value, independent of the atom number.
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