Higher-order correlations and what we can learn about quantum many body problems from experiments

Event Dates: 

Friday, November 22, 2019 - 12:00pm

CTQM Seminar Type: 

  • CTQM Seminar

Seminar Location: 

  • Duane Physics Room G126

Speaker Name(s): 

Jörg Schmiedmayer

Speaker Affiliation(s): 

Vienna Center for Quantum Science and Technology (VCQ), Atominstitut, TU-Wien

Abstract, Event Details: 

The knowledge of all correlation functions of a system is equivalent to solving the corresponding quantum many-body problem. If one can identify the relevant degrees of freedom, the knowledge of a finite set of correlation functions is in many cases enough to determine a sufficiently accurate solution of the corresponding field theory. Complete factorization of the correlation functions is equivalent to identifying the relevant degrees of freedom where the Hamiltonian becomes diagonal. 

To study these concepts in the framework of the quantum Sine-Gordon model which emerges as the field theory description from a pair of tunnel-coupled one-dimensional atomic super-fluids.  Study if, and under which conditions, the higher correlation functions of the phase factorize allows us to characterize the essential features of the model [1]: We detect the relevant quasi-particles, their interactions and the different topologically distinct vacuum-states. 

To extract the propagators and vertices of the quantum simulated Sine-Gordon field theory we evaluate the irreducible 1PI correlations. Our analysis clearly shows the ‘running couplings’ in a the description of a strongly correlated quantum system [2].

This establishes a general method to analyse quantum systems through experiments. It thus represents a crucial ingredient towards the implementation and verification of quantum simulators.

Work performed in collaboration with the groups of Th. Gasenzer und J. Berges (Heidelberg). Supported by the Wittgenstein Prize, the DFG-FWF: SFB ISOQUANT: and the EU: ERC-AdG QuantumRelax

[1] T. Schweigler et al., Nature 545, 323 (2017), arXiv:1505.03126

[2] T. Zache et al. arXiv:1909.12815

Research Category: