Quantum engineering of Rydberg atoms
Sébastien Gleyzes
Laboratoire Kastler Brossel, College de France, CNRS, ENS-PSL Research University, UPMC-Sorbonne Universites, Paris, France
ABSTRACT:
Rydberg states correspond to electron wave function localised at a very
large distance from the nucleus. In our system, we manipulate the state
of an atom with principal quantum number n~ 50. In the presence of a small
electric field defining the quantization axis, the degeneracy between
levels with the same n is lifted. The new eigenstates, called Stark levels,
are defined by the magnetic quantum number m and the parabolic quantum
number n1, with 0≤n1≤ne-|m|-1. Since m remains a good quantum number, it is
possible, using a radio frequency field with a well-defined sigma plus
polarization, to restrict the evolution of the atom to a subspace of the
Stark manifold where the system behaves like a large spin J= (n – 1)/2,
whose frequency is proportional to the local amplitude of the electric
field.
We have used this effective spin to observe Quantum Zeno dynamics, and
showed that, if the Zeno subspace is non-trivial, restricting the evolution
of the system to a subspace of the Hilbert space induces highly non
classical dynamics, leading to the generation of Schrödinger cat state,
quantum superposition of two classically distinct wavefunction of the
electron.
Deterministically generating non-classical Rydberg states opens the way to
application to quantum metrology. We have illustrated this by performing
quantum-enabled measurement of the static electric and magnetic field.