QUANTUM Finite and Infinite Quantum Systems
Entanglement, Coherence and Control

Scientific activities of the various Research Units


The Bari group investigates the physics of cold gases and waveguide QED, and some features of quantum evolutions and quantum metrology. The most recent activity is on the phase diagram of a spin-orbit-coupled spin-1 condensate, and on a new scheme of plenoptic imaging at the diffraction limit. The latter is also being patented.
- BECs. The zero-temperature phase diagram of a spin-orbit coupled condensate with spin 1 has been determined, for both attractive and repulsive spin-spin interactions. We have found the existence of emergent tricritical points and "striped" phases, in which translation invariance is spontaneously broken.
- Quantum imaging. We have unveiled the possibility of obtaining plenoptic imaging by measuring intensity correlations of light, either chaotic or entangled. The proposed scheme enables plenoptic imaging at the diffraction limit, which is not allowed in first-order plenoptic setups.
- Entanglement and Quantum dynamics. A system of two qubits coupled with photons in a linear waveguide has been analyzed. In particular, we have found that the existence of nontrivial bound states entails the possibility of generating entanglement by relaxation.
- Quantum Boundary Conditions. We have unveiled the existence of a non-trivial Berry phase associated to the dynamics of a quantum particle in a box with moving boundaries. The geometric phase is induced by a suitable choice of boundary conditions. Among the most recent highlights:

  • Interview with Francesco Pepe and the QUANTUM collaboration
  • Cover Image of Physical Review Letters, Volume 116, Issue 22
  • Journal of Physics A Highlights of 2016 collection
  • Bologna-Camerino

    The research of the Bologna group focuses on the study of static and dynamic phase transitions of closed quantum many body systems in low dimensions, through the study of entanglement entropy and the calculation of dynamical quantities that rule the appearance of ordered phases. We deal mainly with systems with long-range interactions and/or which show many-body localisation. In addition, in the spirit of quantum simulators, we study the implementation on lattices of gauge field theories.
    The research activity of Camerino is mainly devoted to quantum channels characterization. In particular, the idea of quantum channels with environment assistance has been put forward and in such a context conferencing capacity has been introduced. Furthermore a model of a non-Gaussian quantum channel that stems from the composition of two physically relevant processes occurring in open quantum systems (amplitude damping and dephasing) has been studied in terms of minimum output entropy. On another side, the notion of mutually unbiased unitary bases has been introduced and related to unitary 2-designs.


    The activity of the Catania-Palermo node focuses on the following main topics:
    - Study of time dependent spin models;
    - Driven-dissipative dynamics with non-Hermitian, time-dependent Hamiltonians with PT-symmetry;
    - Quantum transport and quench in atomtronics circuits;
    - Solitons in interacting many-body bosonic systems and ergodicity;
    - Coherent transfer in non-linear circuit QED hybrid structures and synchronization process in chiral waveguides;
    - Dynamical Casimir effect in many-atom systems.


    The activity of the Milano-Como node focuses on the following main topics:
    - Quantum transport and thermodynamics: search for mechanisms to improve the efficiency of thermodynamic quantum machines; explore interaction effects on heat to work conversion at the nanoscale; find new mechanisms and realistic models for heat management and efficient thermal rectification.
    - Quantum information processing in the ultra-strong field-matter coupling regime: explore fundamental limitations, due to the dynamical Casimir effect, for quantum protocols and thermal machines.
    - Properties of transfer matrices originating from banded random matrices, also in relation to the Anderson localisation.


    The activity on the Napoli-Salerno Unit focuses on two main research lines.
    - Casimir effect and Casimir-Polder interaction: by a systematic expansion of the interaction potential in powers of derivatives of the surface height profile, the Casimir-Polder interaction of a particle with a curved material surface was investigated. By means of this technique, one can determine the shift of the spectral lines of a diatomic polar molecule placed near a curved surface. Conformal invariance of Maxwell equations in four euclidean dimensions has been exploited to compute the exact Casimir interaction between two 3-spheres. The separability of Laplace equation in bispherical coordinates has been exploited to study the classical limit of the sphere-plate Casimir interaction.
    - Semi-groups of operators: applications to open quantum systems and quantum information. The quantum dynamical semi-groups, completely positive or not, that increase a quantum entropy were classified. These results hold for the von Neumann entropy, as well as for a general class of functions including the Renyi and the Tsallis entropies. It was also shown that a quantum dynamical semi-group that does not decrease a quantum entropy can be realized as a “generalized twirling semi-group”. Time in quantum mechanics. A new approach was proposed to the problem of time in quantum mechanics, based on the idea of replacing the usual time operator (defined in the literature by various recipes) with a suitable real function on the space of states.


    The research of the Trieste group focuses on the study of the dynamics of quantum correlations in many-body systems with particular focus upon applications in quantum thermodynamics and non-equilibrium processes.
    - In many-body systems, the dynamics of quantum correlations is affected by dissipation and noise as in pump and probe experiments where femtosecond laser pulses can be used to create squeezed phonons on a metallic target and subsequently read off their behavior.
    - Many-body fluctuations scaling with the square root of the number of particles inherit a quantum behavior from the microscopic one and exhibit entanglement at the mesoscopic level.
    - In non-equilibrium processes, the dynamics of quantum correlations affects the exchanges of heat ad work among the parties giving rise to non-Markovian effects. These can be better understood by treating the parties on a same footing rather than effectively eliminating one of them as a large environment.

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