A Quantum Resonator

Chee‐Kong Lee, L. C. Kwek, Jianshu Cao

We study the stochastic resonance of quantum discord (``discord resonance'') in coupled quantum systems and make a comparison with the stochastic resonance of entanglement (``entanglement resonance''). It is found that the discord resonance is much more robust against dephasing noise and thermal effects than the entanglement resonance. We also show that, unlike the entanglement resonance, the level of dissipation at which the discord resonance occurs is not sensitive to dephasing noise. These results suggest that it is easier to detect the discord resonance in actual experiments, where the dephasing noise and temperature are difficult to control.

Andrey G. Grozin

W. A. Lin, L. E. Reichl

The quasienergy spectrum of a particle in an infinite square well perturbed by a monochromatic external field is analyzed in terms of single- and double-resonance Hamiltonians. At small-enough perturbations the quasienergies are accurately given by those obtained from a single-resonance, integrable Hamiltonian. This indicates the existence of a local constant of motion and is a quantum manifestation of the Kolmogorov-Arnold-Moser theorem. At larger perturbations, the quasienergy spacing distributions are Poissonian for the single-resonance Hamiltonian. But for the double-resonance Hamiltonian, the distributions undergo a transition from Poissonian toward Wigner-like behavior when the perturbation is increased from a regime without resonance overlap to a regime with resonance overlap. This indicates the destruction of the local constant of motion through quantum-resonance overlap and its associated quantum number. It is a quantum manifestation of classical-resonance overlap.

A. M. Perelomov

Olivier Henri‐Rousseau, Paul Blaise

Kenta Higuchi, Hisashi Morioka, Etsuo Segawa

We define resonances for finitely perturbed quantum walks as poles of the scattering matrix in the lower half plane. We show a resonance expansion which describes the time evolution in terms of resonances and corresponding Jordan chains. In particular, the decay rate of the survival probability is given by the imaginary part of resonances and the multiplicity. We prove generic simplicity of the resonances, although there are quantum walks with multiple resonances.