B. Wyker

Large-scale quantum coherence of nearly circular wave packets

We demonstrate that the quantum coherence of mesoscopic very-high-n, n~305, Rydberg wave packets travelling along nearly circular orbits can be maintained on microsecond time scales corresponding to hundreds of classical orbital periods. The coherence is probed through collapses and revivals of periodic oscillations in the average electron position. The temporal interferences of spatially separated Schrodinger cat-like wave packets are also observed. A novel hybrid quantum–classical trajectory method is employed to simulate the wave packet dynamics.

Demonstration of turnstiles as a chaotic ionization mechanism in Rydberg atoms.

We present an experimental and theoretical study of the chaotic ionization of quasi-one-dimensional potassium Rydberg wave packets via a classical phase-space turnstile mechanism. Turnstiles form a general transport mechanism for numerous chaotic systems, and this study explicitly illuminates their relevance to atomic ionization. We create time-dependent Rydberg wave packets, subject them to alternating applied electric-field pulses, and measure the electron survival probability. Ionization depends not only on the initial electron energy, but also on the classical phase-space position of the electron with respect to the turnstile--that part of the electron packet inside the turnstile ionizes after the applied ionization sequence, while that part outside the turnstile does not. The survival data thus encode information on the shape and location of the turnstile, in good agreement with theoretical predictions.

Transporting near-circular Bohr-like wave packets using chirped sine waves

Protocols for driving localized high-n (n~300) wave packets in near-circular Bohr-like orbits to higher n states using chirped sine waves are described.

Probing and manipulating high-n near-circular Rydberg wave packets

Fourier transform time domain spectroscopy is used to probe the spatial distribution of near-circular Rydberg wave packets and evaluate protocols for their control and manipulation.

Long-time quantum coherence of near-circular wavepackets

We demonstrate that the quantum coherence of mesoscopic high-n (n ~ 306) Rydberg wavepackets can be maintained for microseconds, i.e. many hundreds of classical orbital periods. The coherence is probed through quantum revivals of the average electron position. A novel hybrid quantum-classical trajectory method is used to simulate the wavepacket dynamics.

Creation of non-dispersive Bohr-like wavepackets

The use of a periodic train of half-cycle pulses to maintain strongly-localized wavepackets in high-n (n ~ 306) atoms that travel in near-circular orbits about the nucleus is demonstrated. The wavepacket is non-dispersive for hundreds of orbits and mimics the original Bohr model of the hydrogen atom.