The occurrence and visibility of spontaneous solitons in ultracold gases

Transcription

1 The occurrence and visibility of spontaneous solitons in ultracold gases Piotr Deuar Institute of Physics, Polish Academy of Sciences Collaboration: Emilia Witkowska, Tomasz Świsłocki, Mariusz Gajda Institute of Physics, Polish Academy of Sciences Jörg Schmiedmayer, Max Kuhnert, Tim Langen Technische Universität Wien Ray Ng McMaster University Nick Proukakis Newcastle University Tomasz Karpiuk, Mirosław Brewczyk University of Białystok Kazimierz Rzążewski, Krzysztof Pawłowski, Przemysław Bienias Center for Theoretical Physics, Polish Academy of Sciences N

2 Collective single shot phenomena Example (1): the Vienna prethermalisation experiment Gring, Kuhnert, Langen, Kitagawa, Bauer, Schreitl, Mazets, Adu Smith, Demler, Schmiedmayer, Science 337, 1318 (2012) Langen, Gring, Kuhnert, Rauer, Geiger, Adu Smith, Mazets, Schmiedmayer, Eur. Phys. J. Special Topics 217, 43 (2013) Measured the distribution of fringe contrast C2 between 1D gases after release from the traps. Phase difference between clouds is reflected in the position of interference fringes The phase difference temperature of a split gas stabilizes at a much smaller value than other quantities. Probed effects that can only be seen by analysing single shot images 2/8

3 Soltions induced by a disturbance Evaporative cooling (temperature quench) Witkowska, PD, Gajda, Rzążewski, PRL 106, (2011) Interaction quench Schmidt, Erne, Nowak, Sexty, Gasenzer, New J. Phys. 14, (2012) B. Damski, W. Żurek, PRL 104, (2010) Uniform gas after chemical potential quench Growth of quasicondensate during thermalization Damski, Żurek, PRL 104, (2010) Swisłocki, PD, arxiv: /8

4 Solitonic phase in thermal equilibrium Solitons in equilibrium with phonons Karpiuk, PD, Bienias, Witkowska, Pawłowski, Gajda, Rzążewski, Brewczyk, PRL 109, (2012) Occur roughly when μ << T << Tc Identified with Type II excitations in Lieb-Liniger gas Karpiuk, Sowinski, Gajda, K. Rzążewski, Brewczyk arxiv: Should be common in existing experiments However, solitons are narrow... density phase Other Brewczyk paper x x 4/8

5 Observability: imprinted vs spontaneous solitons IMPRINTED SOLITONS ΔΦ - U(x) t / ћ WILD SOLITONS Recent advances: single shot (quench not thermal clean background) Burger, Bongs, Dettmer, Ertmer, Sengstock, Sanpera, Shlyapnikov, Lewenstein, PRL 83, 5198 (1999) Denschlag, Simsarian, Feder, Clark, Collins, Cubizolles, Deng, Hagley, Helmerson, Reinhardt, Rolston, Schneider, Phillips, Science 287, 97 (2000) Donadello, Serafini, Tylutki, Pitaevskii, Dalfovo, Lamporesi, Ferrari, arxiv: /8

6 What about dissipation? Many studies see soliton dissipation due to thermal or quantum noise. Martin, Ruostekoski, New J Phys 12, (2010); Martin, Ruostekoski, PRL 104, (2010) Mishmash, Carr, PRL 103, (2009); Mishmash, Danshita, Clark, Carr, PRA 80, and others.. Cockburn, Nistazakis, Horikis, Keverkidis, Proukakis, Frantzeskakis, PRA. 84, (2011) Can solitons survive in the thermal state? SGPE simulation of thermal state (includes thermal noise) Solitons can be born as well as dissipate. 6/8

7 Spontaneous soliton detection (1) Some initial ideas: Phase jump distribution between pixels Counting of density dips at the edges Low T sum of small phonon conbtributions narrow broad higher T includes soliton phase jumps of π Karpiuk, PD, Bienias, Witkowska, Pawłowski, Gajda, Rzążewski, Brewczyk, PRL 109, (2012) 7/8

8 Interferometric imaging of phase As per Vienna experiment (Gring et al 2012). Independent 1D gases EXPANSION DISTORTION t=0 t=0 ( WORK IN PROGRESS ) ideal detector soliton imprinted on detector 2μm blurring false positive widening 8/8

9 Summary Spontaneous collective excitations require different techniques Single images must be analysed Predict the existence of a soliton phase in 1D Bose gases Solitons coexist in a thermal equilibrium with phonons Studied the possibility of their observation with inteferometric imaging The signatures are there, but there are also false positives 9/8