Tunneling through vacuum and molecules

C. A. Bertulani

T. Miyakawa, Christopher P. Search, Pierre Meystre

We analyze the dynamics of a molecular field incoherently pumped by the photoassociation of fermionic atoms and coupled by quantum tunneling in a double-well potential. The relative phase distribution of the molecular modes in each well and their phase coherence are shown to build up owing to quantum-mechanical fluctuations starting from the vacuum state. We identify three qualitatively different steady-state phase distributions, depending on the ratio of the molecule-molecule interaction strength to interwell tunneling, and examine the crossover from a phase-coherent regime to a phase-incoherent regime as this ratio increases.

Xiaolei Liu, Chunchao Yu, Wenxing Yang +1 more

ABSTRACT Optical properties in quantum dot molecules (QDMs), which are implanted in coupled cavities, are researched theoretically. The QDMs are composed of three QDs, and a multi‐level system, including direct and indirect excitons, which can be formed due to tunneling effects therein. Under the strong coupling condition, double Autler‐Townes splitting (ATS) occurs. Then, we implant the QDMs in the coupled cavities, and double Vacuum‐Rabi splitting (VBS) is created together. Four transparency windows are demonstrated. Moreover, the effects of the coupling strengths and frequency detunings on the system absorption spectrum are discussed. Especially, the group index in QDMs controlled by the coupling strengths are explored and group velocity with a reduced factor of 10 6 is revealed. Such a system may be used in on‐chip QD‐based optical devices.

Yuexin Wan, Zhaoxiang Liu, Jinping Yao +6 more

Abstract We report generation of spectrally bright vacuum ultraviolet (VUV) and deep UV (DUV) coherent radiations at the wavelengths of 192 nm, 198 nm and 204 nm. These DUV/VUV radiations originate from resonant four-wave mixing assisted by quantum coherence in tunnel-ionized CO molecules. The electronic coherence is created when the pump pulses resonantly excite electronic transitions of CO+. The technique allows for the selective switch of DUV/VUV wavelengths provided by the abundant energy levels of molecular ions. The developed source can have arbitrary polarization states by manipulating the polarization of the pump pulse. It also exhibits a spectral bandwidth of 5∼7 cm−1, a divergence angle of 3∼5 mrad, a pulse duration of ∼10 ps, and a photon flux of ∼1010 photons/s. The superior temporal and spectral properties give rise to a broadband Raman comb in the DUV/VUV region.