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Andrew D. Greentree

Publications and source records attributed to Andrew D. Greentree.

116 records · Page 7Linked to original sources
arXiv2003

Maximizing the Hilbert space for a finite number of distinguishable quantum states

We consider a quantum system with a finite number of distinguishable quantum states, which may be partitioned freely by a number of quantum particles, assumed to be maximally entangled. We show that if we partition the system into a number of qudits, then the Hilbert space dimension is maximized when each quantum particle is allowed to represent a qudit of order $e$. We demonstrate that the dimensionality of an entangled system, constrained by the total number quantum states, partitioned so as to maximize the number of qutrits will always exceed the dimensionality of other qudit partitioning. We then show that if we relax the requirement of partitioning the system into qudits, but instead let the particles exist in any given state, that the Hilbert space dimension is greatly increased.

quant-ph↗
arXiv2003

Intensity-dependent dispersion under conditions of electromagnetically induced transparency in coherently prepared multi-state atoms

Interest in lossless nonlinearities has focussed on the the dispersive properties of $Λ$ systems under conditions of electromagnetically induced transparency (EIT). We generalize the lambda system by introducing further degenerate states to realize a `Chain $ Λ$' atom where multiple coupling of the probe field significantly enhances the intensity dependent dispersion without compromising the EIT condition.

quant-ph↗
arXiv2001

Resonant and off-resonant transients in electromagnetically induced transparency: turn-on and turn-off dynamics

This paper presents a wide-ranging theoretical and experimental study of non-adiabatic transient phenomena in a $Λ$ EIT system when a strong coupling field is rapidly switched on or off. The theoretical treatment uses a Laplace transform approach to solve the time-dependent density matrix equation. The experiments are carried out in a Rb$^{87}$ MOT. The results show transient probe gain in parameter regions not previously studied, and provide insight into the transition dynamics between bare and dressed states.

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arXiv2001

Observation of transient gain without population inversion in a laser-cooled rubidium lambda system

We have observed clear Rabi oscillations of a weak probe in a strongly driven three-level lambda system in laser-cooled rubidium for the first time. When the coupling field is non-adiabatically switched on using a Pockels cell, transient probe gain without population inversion is obtained in the presence of uncoupled absorptions. Our results are supported by three-state computations.

quant-ph↗
arXiv2001

Observations of a doubly driven V system probed to a fourth level in laser-cooled rubidium

Observations of a doubly driven V system probed to a fourth level in an N configuration are reported. A dressed state analysis is also presented. The expected three-peak spectrum is explored in a cold rubidium sample in a magneto-optic trap. Good agreement is found between the dressed state theory and the experimental spectra once light shifts and uncoupled absorptions in the rubidium system are taken into account.

quant-ph↗
arXiv2001

Robust quantum memory via quantum control

A general scheme for building a quantum memory by transferring quantum information to an essentially decoherence-free memory transition using quantum control is presented and illustrated by computer simulations.

quant-ph↗
arXiv2000

Prospects for photon blockade in four level systems in the N configuration with more than one atom

We show that for appropriate choices of parameters it is possible to achieve photon blockade in idealised one, two and three atom systems. We also include realistic parameter ranges for rubidium as the atomic species. Our results circumvent the doubts cast by recent discussion in the literature (Grangier et al Phys. Rev Lett. 81, 2833 (1998), Imamoglu et al Phys. Rev. Lett. 81, 2836 (1998)) on the possibility of photon blockade in multi-atom systems.

quant-ph↗