Echo in a Single Molecule

Abstract

Echo is a ubiquitous phenomenon found in many physical systems, ranging from spins in magnetic fields to particle beams in hadron accelerators. It is typically observed in inhomogeneously broadened ensembles of nonlinear objects, and is used to eliminate the effects of environmental-induced dephasing, enabling observation of proper, inherent object properties. Here, we report experimental observation of quantum wave packet echoes in a single isolated molecule. In contrast to conventional echoes, here the entire dephasing-rephasing cycle occurs within a single molecule without any inhomogeneous spread of molecular properties, or any interaction with the environment. In our experiments, we use a short laser pulse to impulsively excite a vibrational wave packet in an anharmonic molecular potential, and observe its oscillations and eventual dispersion with time. A second delayed pulsed excitation is applied, giving rise to an echo: a partial recovery of the initial coherent wavepacket. The vibrational dynamics of single molecules is visualized by time-delayed probe pulse dissociating them one at a time. Two mechanisms for the echo formation are discussed: ac Stark-induced molecular potential shaking and creation of depletion-induced "hole" in the nuclear spatial distribution. Interplay between the optically induced echoes and quantum revivals of the vibrational wave packets is observed and theoretically analyzed. The single molecule wave packet echoes may lead to the development of new tools for probing ultrafast intramolecular processes in various molecules.

9 pages, 7 figures

References in corpus (12)

• Quantum wave packet revivals
• Spin-echo of a single electron spin in a quantum dot
• Controlled double-slit electron diffraction
• Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase
• Room-temperature ultrafast non-linear spectroscopy of a single molecule
• Orientation and Alignment Echoes
• Wave Packet Echoes in the Motion of Trapped Atoms
• Echo Spectroscopy in multi-level quantum-mechanical rotors
• Fractional Echoes
• Echoes and revival echoes in systems of anharmonically confined atoms
• Echo in Optical Lattices: Stimulated Revival of Breathing Oscillations
• Nonlinear theory of transverse beam echoes

Cited by in corpus (8)

• Optimal three-state field-free molecular orientation with terahertz pulses
• Molecular alignment echoes probe collision-induced rotational-speed changes
• Echoes in Unidirectionally Rotating Molecules
• Echo-enhanced molecular orientation at high temperatures
• Long-living dark coherence brought to light by magnetic-field controlled photon echo
• Echoes in a Single Quantum Kerr-nonlinear Oscillator
• Impulsively Excited Gravitational Quantum States: Echoes and Time-resolved Spectroscopy
• Echoes in a parametrically perturbed Kerr-nonlinear oscillator