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Speakers: Emil Yuzbashyan (Rutgers University, USA), Jiri Minar (UvA, QuSoft) and Axel Cortes Cubero (UU). Location: Amsterdam.

Event details of Triangle meeting Quantum and Topological matter
Date 23 November 2018
Time 13:30 -18:30
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Programme

13:30 - 14:00 Welcome coffee and  tea

14:00 - 15:00 Emil Yuzbashyan (Rutgers University, USA) - Integrable time-dependent Hamiltonians 

15:00 - 16:00  Jiri Minar (UvA, QuSoft) - Dissipative quantum state preparation and metastability in two-photon micromasers 

16:00 - 16:30 Coffee, Tea

16:30 - 17:30 Axel Cortes Cubero (UU) - Integrable field theories in the presence of a background

17:30 - 18:30 Drinks and snacks

Abstracts

Emil Yuzbashyan (Rutgers University, USA) - Integrable time-dependent Hamiltonians  

I will outline a way to make the parameters (e.g., the interaction strength) of certain quantum integrable models time-dependent without breaking their integrability. Interesting many-body models that emerge from this approach include a superconductor with the interaction strength inversely proportional to time, a Floquet BCS superconductor, and the problem of molecular production in an atomic Fermi gas swept through a Feshbach resonance as well as various models of multi-level Landau-Zener tunneling.
Amazingly, the non-stationary Schrodinger equation for all these models has a similar structure and is integrable with a similar technique as the famous Knizhnikov-Zamolodchikov equations of the Conformal Field Theory. I will use this to solve for their dynamics and, independently, discuss some interesting physics that emerges at large times.

Jiri Minar (UvA, QuSoft) - Dissipative quantum state preparation and metastability in two-photon micromasers

In this talk I will discuss the dynamics of two-photon micromasers for quantum state preparation with applications to quantum metrology and quantum information processing.  The traditional two-photon micromasers based on three-level systems suffer from spurious Stark shifts, both static and dynamical, resulting in squeezed vacuum or Fock state as their steady state. We propose a scheme based on (5+1)-level atoms which overcomes this limitation. This in turn opens possibilities for a driven-dissipative generation of a plethora of novel quantum states, including ones reminiscent of the so-called grid states.

Next I will review the dynamics of open quantum systems and the superopator formalism which allows for the analysis of realistic imperfections, namely single-photon losses and higher-order corrections to the effective two-photon Hamiltonian. Here, we develop a theory of metastability which yields analytical expressions for metastable and steady states and the associated timescales. We characterize the states in terms of the Wigner function and the quantum Fisher information for phase estimation. We identify regions in the parameter space, which feature the quantum Fisher information enhanced order of magnitude beyond the standard quantum limit. Importantly, we find that the mixed steady states can still feature an enhancement beyond the standard quantum limit, providing thus an efficient and robust scheme for driven-dissipative quantum state generation.

Axel Cortes Cubero (UU) - Integrable field theories in the presence of a background

Integrability in quantum field theory provides powerful analytic tools that enable the computation of exact matrix elements of operators, and correlation functions. The computation of such correlators in the presence of a non-trivial background, such as when the system is at finite temperature (or in a generalized Gibbs ensembles), has remained much more elusive, as one needs to consider states with an extensive number of particles. In this talk I will discuss the newly proposed “Thermodynamic Bootstrap Program”: an axiomatic approach to compute such correlators, taking into account the non-trivial effects of the thermodynamic background on physical particles.

Location

FNWI Building, Science Park 904 Amsterdam, room C4.278

Note that the railway station Amsterdam Science Park is within walking distance from the faculty building.