Two-point density correlations of quasicondensates in free expansion

Manz, Stephanie; Bücker, Robert; Betz, Thomas; Koller, Ch.; Hofferberth, Sebastian; Mazets, I. E.; Imambekov, Adilet; Demler, Eugene; Perrin, Aurélien; Schmiedmayer, Jörg; Schumm, Thorsten

doi:10.1103/physreva.81.031610

Cited by 104 publications

(134 citation statements)

References 19 publications

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“…20 µm for the coupled thermal equilibrium data. We can measure λ T independently by looking at speckle patterns in time of flight [34]. Using the same procedure to fit a temperature to the fast cooled (= non-thermal) data gives λ T = 14 .…”

Section: E Sine-gordon Modelmentioning

confidence: 99%

Experimental characterization of a quantum many-body system via higher-order correlations

Schweigler

Kasper

Erne

et al. 2017

Nature

241

319

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Section: E Sine-gordon Modelmentioning

confidence: 99%

Experimental characterization of a quantum many-body system via higher-order correlations

Schweigler

Kasper

Erne

et al. 2017

Nature

241

319

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“…4). The temperature before splitting, T init , was obtained through measurements of the second-order correlation function of longitudinal density fluctuations after time of flight [24,32]. The results (blue squares in Fig.…”

Section: Fig 4 (Color)mentioning

confidence: 99%

Multimode Dynamics and Emergence of a Characteristic Length Scale in a One-Dimensional Quantum System

et al. 2013

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We study the nonequilibrium dynamics of a coherently split one-dimensional Bose gas by measuring the full probability distribution functions of matter-wave interference. Observing the system on different length scales allows us to probe the dynamics of excitations on different energy scales, revealing two distinct length-scale-dependent regimes of relaxation. We measure the crossover length scale separating these two regimes and identify it with the prethermalized phase-correlation length of the system. Our approach enables a direct observation of the multimode dynamics characterizing one-dimensional quantum systems. The nonequilibrium dynamics of many-body quantum systems and their pathway towards equilibrium is of fundamental importance in vastly different fields of physics. Open questions appear, for example, in high-energy physics for understanding quark-gluon plasma [1][2][3], in cosmology for describing preheating of the early Universe [4], or in the comprehension of relaxation processes in condensed-matter systems [5,6].Because of their isolation from the environment and their tunability, ultracold atom systems have triggered many studies of nonequilibrium dynamics in closed interacting quantum systems, with particular interest drawn to quantum quenches [7,8]. Important questions are related to systems where the dynamics is constrained by several constants of motion [9] and to the possible description of nonequilibrium states by generalized statistical mechanics ensembles [10,11].Recently, we reported the experimental observation of prethermalization in a coherently split one-dimensional (1D) ultracold Bose gas [12], made possible by a characterization of the dynamical states through measurements of full distribution functions [13,14]. Prethermalization [15] was understood as the rapid relaxation to a steady state exhibiting thermal-like properties but differing from the true thermal equilibrium that is eventually expected to occur on longer time scales [16][17][18][19][20].In this Letter, we study the relaxation process [21] leading to the prethermalized state by measuring the full (probability) distribution functions (FDFs) of phase and contrast of matter-wave interference. We probe the 1D system on different length scales to investigate its multimode dynamics, which reveals two distinct regimes separated by a characteristic crossover length scale. We measure this characteristic length scale and identify it with the effective thermal phase-correlation length of the prethermalized system.We prepare a quasi-1D Bose gas of several thousand 87 Rb atoms in an elongated (along the z direction) magnetic microtrap on an atom chip [22] at a (tunable) temperature between 20 and 120 nK. The gas is coherently split along the radial (x) direction using a symmetric radio-frequency dressed-state double-well potential [23], creating two uncoupled 1D gases separated by a distance of 3:1 m [ Fig. 1(a)]. The longitudinal and radial trap frequencies in the double well are 7 Hz and 1.4 kHz, respectively, and the size of the...

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“…Our correlation measurements with ultracold 4 He * atoms may pave the way for similar future quantum atom optics tests of the tenets of quantum mechanics for massive particles 12 . Moreover, higher-order correlations may play an important role as accurate probes of the 3D condensates 28 , as well as intriguing quantum states incorporating lower dimensions 29 and other strongly correlated systems 17 . Finally, they may also provide unambiguous evidence of p-and d-wave pairings 30 , which may offer valuable insights into high-temperature superconductivity.…”

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confidence: 99%

Ideal n-body correlations with massive particles

et al. 2013

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In 1963 Glauber introduced the modern theory of quantum coherence 1 , which extended the concept of first-order (onebody) correlations, describing phase coherence of classical waves, to include higher-order (n-body) quantum correlations characterizing the interference of multiple particles. Whereas the quantum coherence of photons is a mature cornerstone of quantum optics, the quantum coherence properties of massive particles remain largely unexplored. To investigate these properties, here we use a uniquely correlated 2 source of atoms that allows us to observe n-body correlations up to the sixthorder at the ideal theoretical limit (n!). Our measurements constitute a direct demonstration of the validity of one of the most widely used theorems in quantum many-body theory-Wick's theorem 3 -for a thermal ensemble of massive particles. Measurements involving n-body correlations may play an important role in the understanding of thermalization of isolated quantum systems 4 and the thermodynamics of exotic many-body systems, such as Efimov trimers 5 .Glauber's modern theory of optical coherence and the famous Hanbury Brown-Twiss effect 6 were pivotal in the establishment of the field of quantum optics. Importantly, the definition of a coherent state required coherence to all orders, which for example distinguishes a monochromatic but incoherent thermal source of light from a truly coherent source such as a laser. Higher-order correlation functions therefore provide a more rigorous test of coherence.Higher-order correlations, characterized by an n-body correlation function g (n) , are of general interest and have been investigated in many fields of physics including astronomy 6 , particle physics 7 , quantum optics 8 , and quantum atom optics 9 . In particular they have been a fruitful area of research in the field of quantum optics, where they have been used to investigate the properties of laser light, including heralded single photons 10 , and the statistics of parametric down-conversion sources 11 . State-of-the-art quantum optics experiments have measured photon correlation functions up to sixth order for quasi-thermal sources 8 , allowing the possibility of performing full quantum state tomography 12 .Higher-order correlations experiments with massive particles are currently approaching the same level of maturity as with photons. So far, experiments have directly observed correlations up to fourth order with single-atom-sensitive detection techniques for ultracold atomic bosons 9,13,14 , and second-order correlations for an atomic source of fermions 15 demonstrating the uniquely quantum mechanical property of atom-atom antibunching. Alternative, indirect techniques have also been employed to investigate higher-order correlations, including the measurements of twobody (photoassociation 16 ) and three-body 17 loss rates that are sensitive, respectively, to second-and third-order correlation functions. Interestingly, fermionic atom pairs 18 and fermionic antibunching 19 have also been observed in the atomic shot no...

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Two-point density correlations of quasicondensates in free expansion

Cited by 104 publications

References 19 publications

Experimental characterization of a quantum many-body system via higher-order correlations

Experimental characterization of a quantum many-body system via higher-order correlations

Multimode Dynamics and Emergence of a Characteristic Length Scale in a One-Dimensional Quantum System

Ideal n-body correlations with massive particles

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