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- 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)

- 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)

- 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)

- 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)

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)

- G Behinaein, V Ramareddy, P Ahmadi, G S Summy
- Physical review letters
- 2006

We experimentally explore the underlying pseudoclassical phase space structure of the quantum delta-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… (More)

- M B d'Arcy, R M Godun, M K Oberthaler, G S Summy, K Burnett, S A Gardiner
- Physical review. E, Statistical, nonlinear, and…
- 2001

We describe measurements of the mean energy of an ensemble of laser-cooled atoms in an atom optical system in which the cold atoms, falling freely under gravity, receive approximate delta-kicks from a pulsed standing wave of laser light. We call this system a "delta-kicked accelerator." Additionally, we can counteract the effect of gravity by appropriate… (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 quasi-momentum 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)

- 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)

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 3 P 2 metastable energy level of neon to determine the dynamics of the populations and coherences that are formed due to… (More)