**January 24 2019**

**24 till 25.01.2019: Visit of Prof. Ennio Arimondo (Università di Pisa and INO-CNR)**

Prof. Ennio Arimondo (Università di Pisa and INO-CNR) will visit us from Thursday 24.01.2019 to Friday 25.01.2019 .

He will give a talk in the physics colloquium on Thursday 24.01.2019 at 16:15 in building C6 4 lecture hall II.

## Superadiabatic control of quantum systems

Quantum control and quantum computation, relying on the
engineering of ad-hoc Hamiltonians, explore the evolution of quantum
systems towards precisely defined targets. A basic task is the preparation of
the system in a given quantum eigenstate. In particular an important goal is
to keep a quantum system in the lowest energy state. This task is typically
realized by a very slow adiabatic modification of the control Hamiltonian.
Within the last few years a large theoretical and experimental effort has
developed superadiabatic quantum protocols providing perfect and very fast
quantum control. This control of quantum processes was developed in
different areas from atomic physics, to solid-state physics and molecular
physics.
The "simplest non-simple quantum problem" is the evolution of a two-
level quantum system with a time-dependent Hamiltonian. A paradigmatic
example of such a system is the Landau-Zener (LZ) problem, in which two
levels whose energy depends on time experience an avoided crossing. If the
time variation of the energy levels is linear, the resulting evolution gives rise
to the well-known expression for the LZ tunneling. For this problem the goal
of perfect preparation of the final state can only be achieved for infinitely
slow sweep speeds or for infinitely large coupling strengths, both of which
are impractical.
The speeded-up superadiabatic approach is to use shortcuts to
adiabaticity protocols, which may be defined broadly as the processes
leading to the same final target state in a shorter time. These protocols for a
given time-varying Hamiltonian construct an auxiliary Hamiltonian that
cancels the non-adiabatic part of the original Hamiltonian and thus ensures
the targeted quantum evolution. Similar schemes have been proposed for
systems with three or more levels. A large variety of alternative protocols
have been proposed in order to obtain similar efficient and fast transfers.
The presentation is focused on the basic of the superadiabatic
approach, and on few experimental results obtained at Pisa and elsewhere..

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