Biomedical subjects

J J Hope

Publications and source records attributed to J J Hope.

5 recordsLinked to original sources

PubMed2006

Achieving peak brightness in an atom laser.

In this Letter we present experimental results and a simple analytic theory on the first continuous (long pulse) Raman atom laser. We analyze the flux and brightness of a generic two state atom laser with an analytic model that shows excellent agreement with our experiments. We show that, for the same source size, the brightness achievable with a Raman atom laser is at least 3 orders of magnitude greater than achievable in any other demonstrated continuously outcoupled atom laser.

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PubMed2006

Generating controllable atom-light entanglement with a Raman atom laser system.

We introduce a scheme for creating continuous variable entanglement between an atomic beam and an optical field, by using squeezed light to outcouple atoms from a Bose-Einstein condensate via a Raman transition. We model the full multimode dynamics of the atom laser beam and the squeezed optical field and show that, with appropriate two-photon detuning and two-photon Rabi frequency, the transmitted light is entangled in amplitude and phase with the outcoupled atom laser beam. The degree of entanglement is controllable via changes in the two-photon Rabi frequency of the outcoupling process.

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PubMed2004

Limit to minimally destructive optical detection of atoms.

All optical techniques used to probe the properties of Bose-Einstein condensates have been based on dispersion and absorption that can be described by a two-level atom. Both phenomena lead to spontaneous emission that is destructive at the low energies involved with ultracold atomic systems. Recently, both were shown to lead to the same limit to the signal to noise ratio for a given destruction. We develop a new method for calculating the phase shift of a laser beam and show that no single-pass optical technique using classical light and a three-level atom can exceed this limit. This puts significant restrictions on potential nondestructive measurement schemes.

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PubMed2002

Stability of continuously pumped atom lasers.

A multimode model of a continuously pumped atom laser is shown to be unstable below a critical value of the scattering length. Above the critical scattering length, the atom laser reaches a steady state, the stability of which increases with pumping. Below this limit the laser does not reach a steady state. This instability results from the competition between gain and loss for the excited states of the lasing mode. It will determine a fundamental limit for the linewidth of an atom laser beam.

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PubMed2001

Quantum superchemistry: dynamical quantum effects in coupled atomic and molecular Bose-Einstein condensates.

We show that in certain parameter regimes there is a macroscopic dynamical breakdown of the Gross-Pitaevskii equation. Stochastic field equations for coupled atomic and molecular condensates are derived using the functional positive- P representation. These equations describe the full quantum state of the coupled condensates and include the commonly used Gross-Pitaevskii equation as the noiseless limit. The full quantum theory includes the spontaneous processes which will become significant when the atomic population is low. The experimental signature of the quantum effects will be the time scale of the revival of the atomic population after a near total conversion to the molecular condensate.

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