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We experimentally explore the underlying pseudoclassical phase space structure of the quantum -kicked accelerator. This was achieved by exposing a Bose-Einstein condensate to the spatially corrugated potential created by pulses of an off-resonant standing light wave. For the first time quantum accelerator modes were realized in such a system. By utilizing… (More)

- I Dana, V Ramareddy, I Talukdar, G S Summy
- Physical review letters
- 2008

Quantum-resonance ratchets associated with the kicked particle are experimentally realized for arbitrary quasimomentum using a Bose-Einstein condensate (BEC) exposed to a pulsed standing light wave. The ratchet effect for general quasimomentum arises even though both the standing-wave potential and the initial state of the BEC have a point symmetry. The… (More)

- S Schlunk, M B D'Arcy, S A Gardiner, G S Summy
- Physical review letters
- 2003

Using a freely falling cloud of cold cesium atoms periodically kicked by pulses from a vertical standing wave of laser light, we present the first experimental observation of high-order quantum accelerator modes. This confirms the recent prediction by Fishman, Guarneri, and Rebuzzini [Phys. Rev. Lett. 89, 084101 (2002)]]. We also show how these accelerator… (More)

- S Schlunk, M B D'Arcy, S A Gardiner, D Cassettari, R M Godun, G S Summy
- Physical review letters
- 2003

We experimentally and numerically investigate the quantum accelerator mode dynamics of an atom optical realization of the quantum delta-kicked accelerator, whose classical dynamics are chaotic. Using a Ramsey-type experiment, we observe interference, demonstrating that quantum accelerator modes are formed coherently. We construct a link between the behavior… (More)

- M B d'Arcy, R M Godun, M K Oberthaler, D Cassettari, G S Summy
- Physical review letters
- 2001

We present detailed observations of the quantum delta-kicked rotor in the vicinity of a quantum resonance. Our experiment consists of an ensemble of cold cesium atoms subject to a pulsed off-resonant standing wave of light. We measure the mean energy and show clearly that at the quantum resonance it is a local maximum. We also examine the effect of noise on… (More)

We study the evolution of a trapped atomic cloud subject to a trapping frequency jump for two cases: stationary and moving centre of mass. In the first case, the frequency jump initiates oscillations in the cloud’s momentum and size. At certain times we find the temperature is significantly reduced. When the oscillation amplitude becomes large enough, local… (More)

- I. Dana, V. B. Roitberg, V. Ramareddy, I. Talukdar, G. S. Summy
- I. J. Bifurcation and Chaos
- 2010

A theory of quantum ratchets for a particle periodically kicked by a general periodic potential under quantum-resonance conditions is developed for arbitrary values of the conserved quasimomentum β. A special case of this theory is experimentally realized using a Bose–Einstein condensate (BEC) exposed to a pulsed standing light wave. While this case… (More)

We present a general, semi-classical theory describing the interaction of an atom with an internal state consisting of a number of degenerate energy levels with static and oscillating magnetic fields. This general theory is applied to the P2 metastable energy level of neon to determine the dynamics of the populations and coherences that are formed due to… (More)

- I Talukdar, R Shrestha, G S Summy
- Physical review letters
- 2010

We experimentally investigate the sub-Fourier behavior of a δ-kicked-rotor resonance by performing a measurement of the fidelity or overlap of a Bose-Einstein condensate exposed to a periodically pulsed standing wave. The temporal width of the fidelity resonance peak centered at the Talbot time and zero initial momentum exhibits an inverse cube pulse number… (More)

- R K Shrestha, J Ni, W K Lam, G S Summy, S Wimberger
- Physical review. E, Statistical, nonlinear, and…
- 2013

We report measurements of dynamical tunneling rates of a Bose-Einstein condensate across a barrier in classical phase space. The atoms are initially prepared in quantum states that extend over a classically regular island region. We focus on the specific system of quantum accelerator modes of the kicked rotor in the presence of gravity. Our experimental… (More)