scholarly journals Two- and three-body contacts in the unitary Bose gas

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 377-380 ◽  
Author(s):  
Richard J. Fletcher ◽  
Raphael Lopes ◽  
Jay Man ◽  
Nir Navon ◽  
Robert P. Smith ◽  
...  
Keyword(s):  
Bose Gas ◽  
Many Body ◽  
Body Contact ◽  
Wide Range ◽  
Pairwise Correlations ◽  
Efimov Physics ◽  
Many Body Systems ◽  
Three Body ◽  
Profound Insight

In many-body systems governed by pairwise contact interactions, a wide range of observables is linked by a single parameter, the two-body contact, which quantifies two-particle correlations. This profound insight has transformed our understanding of strongly interacting Fermi gases. Using Ramsey interferometry, we studied coherent evolution of the resonantly interacting Bose gas, and we show here that it cannot be explained by only pairwise correlations. Our experiments reveal the crucial role of three-body correlations arising from Efimov physics and provide a direct measurement of the associated three-body contact.

scholarly journals Universal relations for ultracold reactive molecules

2020 ◽  
Vol 6 (51) ◽  
pp. eabd4699
Author(s):  
Mingyuan He ◽  
Chenwei Lv ◽  
Hai-Qing Lin ◽  
Qi Zhou
Keyword(s):  
Critical Role ◽  
Interaction Strength ◽  
Quantum Correlations ◽  
Polar Molecules ◽  
Many Body ◽  
Density Correlation ◽  
Ultracold Polar Molecules ◽  
Unexplored Area ◽  
Many Body Systems

The realization of ultracold polar molecules in laboratories has pushed physics and chemistry to new realms. In particular, these polar molecules offer scientists unprecedented opportunities to explore chemical reactions in the ultracold regime where quantum effects become profound. However, a key question about how two-body losses depend on quantum correlations in interacting many-body systems remains open so far. Here, we present a number of universal relations that directly connect two-body losses to other physical observables, including the momentum distribution and density correlation functions. These relations, which are valid for arbitrary microscopic parameters, such as the particle number, the temperature, and the interaction strength, unfold the critical role of contacts, a fundamental quantity of dilute quantum systems, in determining the reaction rate of quantum reactive molecules in a many-body environment. Our work opens the door to an unexplored area intertwining quantum chemistry; atomic, molecular, and optical physics; and condensed matter physics.

scholarly journals On the widths and binding energies of K− nuclear states and the role of K− multi-nucleon interactions

2018 ◽  
Vol 181 ◽  
pp. 01009
Author(s):  
Jaroslava Hrtankova ◽  
Jiří Mareš
Keyword(s):  
Bound States ◽  
Binding Energies ◽  
Many Body ◽  
Nucleon Interaction ◽  
Substantial Impact ◽  
Coupled Channels ◽  
Self Consistent ◽  
Interaction Term ◽  
Many Body Systems

We report on our recent self-consistent calculations of K− nuclear quasi-bound states using K− optical potentials derived from chirally motivated meson-baryon coupled channels models [1, 2]. The K− single-nucleon potentials were supplemented by a phenomenological K− multi-nucleon interaction term introduced to achieve good fits to K− atom data. We demonstrate a substantial impact of the K− multi-nucleon absorption on the widths of K− nuclear states. If such states ever exist in nuclear many-body systems, their widths are excessively large to allow observation.

scholarly journals Non-equilibrium dynamics of an ultracold Bose gas under multi-pulsed interaction quenches

2016 ◽  
Vol 30 (30) ◽  
pp. 1650367 ◽  
Author(s):  
Lei Chen ◽  
Zhidong Zhang ◽  
Zhaoxin Liang
Keyword(s):  
Bose Gas ◽  
Quantum Gases ◽  
Zero Temperature ◽  
Many Body ◽  
Equilibrium Dynamics ◽  
Many Body Systems ◽  
Multiple Interaction ◽  
The One ◽  
Body Correlation ◽  
Non Equilibrium

We investigate the non-equilibrium properties of a weakly interacting Bose gas subjected to a multi-pulsed quench at zero temperature, where the interaction parameter in the Hamiltonian system switches between values [Formula: see text] and [Formula: see text] for multiple times. The one-body and two-body correlation functions as well as Tan’s contact are calculated. The quench induced excitations are shown to increase with the number of quenches for both [Formula: see text] and [Formula: see text]. This implies the possibility to use multi-pulsed quantum quench as a more powerful way as compared to the “one-off” quench in controllable explorations of non-equilibrium quantum many-body systems. In addition, we study the ultra-short-range property of the two-body correlation function after multiple interaction quenches, which can serve as a probe of the “Tan’s contact” in the experiments. Our findings allow for an experimental probe using state of the art techniques with ultracold quantum gases.

THE SURPRISING PHENOMENON OF LEVEL MERGING IN FINITE FERMI SYSTEMS

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4452-4463
Author(s):  
JOHN W. CLARK ◽  
VICTOR A. KHODEL ◽  
HAOCHEN LI ◽  
MIKHAIL V. ZVEREV
Keyword(s):  
Single Particle ◽  
Energy Levels ◽  
Fermi System ◽  
Particle Energy ◽  
Particle Spectrum ◽  
Many Body ◽  
Occupation Numbers ◽  
Inherent Feature ◽  
Wide Range ◽  
Many Body Systems

When applied to a finite Fermi system having a degenerate single-particle spectrum, the Landau-Migdal Fermi-liquid approach leaves room for the possibility that different single-particle energy levels merge with one another. It will be argued that the opportunity for this behavior exists over a wide range of strongly interacting quantum many-body systems. An inherent feature of the mergence phenomenon is the presence of nonintegral quasiparticle occupation numbers, which implies a radical modification of the standard quasiparticle picture. Consequences of this alteration are surveyed for nuclear, atomic, and solid-state systems.

scholarly journals Observing non-ergodicity due to kinetic constraints in tilted Fermi-Hubbard chains

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sebastian Scherg ◽  
Thomas Kohlert ◽  
Pablo Sala ◽  
Frank Pollmann ◽  
Bharath Hebbe Madhusudhana ◽  
...  
Keyword(s):  
Density Wave ◽  
Many Body ◽  
Initial State ◽  
Free System ◽  
One Dimensional ◽  
Ergodic Behavior ◽  
Wide Range ◽  
Clean System ◽  
Initial Charge ◽  
Many Body Systems

AbstractThe thermalization of isolated quantum many-body systems is deeply related to fundamental questions of quantum information theory. While integrable or many-body localized systems display non-ergodic behavior due to extensively many conserved quantities, recent theoretical studies have identified a rich variety of more exotic phenomena in between these two extreme limits. The tilted one-dimensional Fermi-Hubbard model, which is readily accessible in experiments with ultracold atoms, emerged as an intriguing playground to study non-ergodic behavior in a clean disorder-free system. While non-ergodic behavior was established theoretically in certain limiting cases, there is no complete understanding of the complex thermalization properties of this model. In this work, we experimentally study the relaxation of an initial charge-density wave and find a remarkably long-lived initial-state memory over a wide range of parameters. Our observations are well reproduced by numerical simulations of a clean system. Using analytical calculations we further provide a detailed microscopic understanding of this behavior, which can be attributed to emergent kinetic constraints.

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