1,368 research outputs found
Quantum computers,Computer quantistici
No full textA cosa serve un computer quantistico e come si puo' realizzare fisicament
Quantum control in strongly driven optical lattices
No full textMatter waves can be coherently and adiabatically loaded and controlled in
strongly driven optical lattices. This coherent control is used in order to
modify the modulus and the sign of the tunneling matrix element in the
tunneling Hamiltonian. Our findings pave the way for studies of driven quantum
systems and new methods for engineering Hamiltonians that are impossible to
realize with static techniques
Experimental investigation of tunneling times using Bose-Einstein condensates
No full textThe time it takes a quantum system to complete a tunneling event (which in
the case of cross-barrier tunneling can be viewed as the time spent in a
classically forbidden area) is related to the time required for a state to
evolve to an orthogonal state, and an observation, i.e., a quantum mechanical
projection on a particular basis, is required to distinguish one state from
another. We have performed time-resolved measurements of Landau-Zener tunneling
of Bose-Einstein condensates in accelerated optical lattices, clearly resolving
the steplike time dependence of the band populations. The use of different
protocols enabled us to access the tunneling probability, in two different
bases, namely, the adiabatic basis and the diabatic basis. The adiabatic basis
corresponds to the eigenstates of the lattice, and the diabatic one to the
freeparticle momentum eigenstates. Our findings pave the way towards more
quantitative studies of the tunneling time for LZ transitions, which are of
current interest in the context of optimal quantum control and the quantum
speed limit
Stability of small-amplitude normal modes of a Bose–Einstein condensate with a singly quantized vortex confined in an optical lattice
No full textControlling Atomic Matter waves by shaking
No full textQuantum particles tunneling between the sites of a periodic lattice can be made to slow down, stop or turn around by shaking the lattice back and forth. This simple method suggests a new kind of quantum control and the creation of “dressed matter waves”
Observation of Stückelberg oscillations in accelerated optical lattices
No full textWe report the experimental observation of St\"{u}ckelberg oscillations of
matter waves in optical lattices. Extending previous work on Landau-Zener
tunneling of Bose-Einstein condensates in optical lattices, we study the
effects of the accumulated phase between two successive crossings of the
Brillouin zone edge. Our results agree well with a simple model for multiple
Landau-Zener tunneling events taking into account the band structure of the
optical lattice
Engineered quantum tunnelling in extended periodic potentials
No full textQuantum tunnelling from a tilted, but otherwise periodic potential is
studied. Our theoretical and experimental results show that, by controlling the
system's parameters, we can engineer the escape rate of a Bose-Einstein
condensate to an exceptional degree. Possible applications of this atom-optics
realization of the open Wannier-Stark system are discussed
- …
