Coherent control of quantum dynamics in laser kicked molecular rotors

A. Espaignol, Franck Billard, E. Hertz +5 more

Purely quantum phenomena such as dynamical localization (DL) can be observed in a molecular rotor subjected to a periodic train of short and intense laser pulses in the gas phase. Using requantized Classical Molecular Dynamics Simulations, we investigate the impact of collisional effects for O2 molecules. We consider different trains of kicks for which the system exhibits quantum resonance, DL, or Bloch oscillations under collision-free conditions. Within achievable experimental conditions, we demonstrate that, as the gas pressure increases, all the dynamics become progressively similar, leading to a quantum-to-classical transition. We study how decoherence induced by intermolecular collisions reduces the quantum interferences through loss of memory. These findings pave the way for future experimental investigations and further theoretical studies on the influence of dissipation on quantum effects in rotational dynamics.

Jennifer L. Herek, Riccardo Fanciulli, Janne Savolainen

Bern Kohler, Jeffrey L. Krause, Robert M. Whitnell +3 more

Andrei Kamalov, Douglas W. Broege, P. H. Bucksbaum

The periodically $\ensuremath{\delta}$-kicked quantum linear rotor is known to experience nonclassical bounded energy growth due to quantum dynamical localization in angular momentum space. We study the effect of random deviations of the kick period in simulations and experiments. This breaks the energy and angular momentum localization and increases the rotational alignment, which is the analog of the onset of Anderson localization in one-dimensional chains.

Jianying Zhou, Jianhua Zeng, Juntao Li

Steven Tomsovic, Juan Diego Urbina, Klaus Richter

One major objective of controlling classical chaotic dynamical systems is exploiting the system's extreme sensitivity to initial conditions in order to arrive at a predetermined target state. In a recent letter [Phys.~Rev.~Lett. 130, 020201 (2023)], a generalization of this targeting method to quantum systems was demonstrated using successive unitary transformations that counter the natural spreading of a quantum state. In this paper further details are given and an important quite general extension is established. In particular, an alternate approach to constructing the coherent control dynamics is given, which introduces a new time-dependent, locally stable control Hamiltonian that continues to use the chaotic heteroclinic orbits previously introduced, but without the need of countering quantum state spreading. Implementing that extension for the quantum kicked rotor generates a much simpler approximate control technique than discussed in the letter, which is a little less accurate, but far more easily realizable in experiments. The simpler method's error can still be made to vanish as $\hbar \rightarrow 0$.