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Seminars and Colloquia
The ultimate limits of quantum control: Super‐adiabatic and super‐fast driving of two‐level quantum systems
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Europe/Rome
131 (INFN edificio C)
131
INFN edificio C
Description
The ability to accurately control a quantum system is a fundamental requirement in many areas of modern science such as quantum information processing, coherent manipulation of molecular systems and high precision measurements. The concept of adiabaticity refers to the possibility of guiding a quantum mechanical system from an initial to some desired final state by changing a control parameter in such a way that the system never leaves its instantaneous ground state. Typically, a high degree of adiabaticity requires that parameter change to be very slow. In the simplest Landau‐Zener model of a two‐level quantum system, a perfect adiabatic following of the ground state requires an infinitely slow variation of the control parameter. On the other hand, in quantum control it is often desirable to minimize the time required to reach the final state since decoherence, caused by coupling to the environment, tends to destroy the quantum mechanical superpositions.
In my talk I will present experimental results on the preparation of a desired quantum state with 100% fidelity using specially designed driving protocols. In particular, by modelling a two‐level quantum system using a Bose‐Einstein condensate inside an optical lattice we realize protocols that approach the quantum speed limit set by the Heisenberg uncertainty principle, as well as the recently proposed superadiabatic (or transitionless) driving in which the system perfectly tracks an instantaneous adiabatic eigenstate. These superadiabatic high‐fidelity driving protocols are robust against variations in the system’s parameters, which makes them attractive for real‐life applications in which perfect control is required under imperfect conditions, such as in quantum information, nuclear magnetic resonance imaging or the coherent control of chemical reactions.
In my talk I will present experimental results on the preparation of a desired quantum state with 100% fidelity using specially designed driving protocols. In particular, by modelling a two‐level quantum system using a Bose‐Einstein condensate inside an optical lattice we realize protocols that approach the quantum speed limit set by the Heisenberg uncertainty principle, as well as the recently proposed superadiabatic (or transitionless) driving in which the system perfectly tracks an instantaneous adiabatic eigenstate. These superadiabatic high‐fidelity driving protocols are robust against variations in the system’s parameters, which makes them attractive for real‐life applications in which perfect control is required under imperfect conditions, such as in quantum information, nuclear magnetic resonance imaging or the coherent control of chemical reactions.