Oxford ion-trap quantum computing project

Lucas, David M.; Donald, C. J. S.; Home, Jonathan; McDonnell, Michael A.; Ramos, A.; Stacey, D. N.; Stacey, J.-P.; Steane, Andrew M.; Webster, S. C.

doi:10.1098/rsta.2003.1209

Cited by 16 publications

(7 citation statements)

References 15 publications

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“…However, it should not be forgotten that it is often heating rate, ṅ, and not the noise per se, which is of interest for many trapped-ion applications. There are, obviously, many considerations which go into selection of ion species to be used (Jefferts et al, 1998;Wineland et al, 2003;Lucas et al, 2003). One aspect which may be added to the list of considerations is that the heating rate is inversely proportional to the ion mass.…”

Section: A Reduction Of Noisementioning

confidence: 99%

Ion-trap measurements of electric-field noise near surfaces

et al. 2015

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Electric-field noise near surfaces is a common problem in diverse areas of physics, and a limiting factor for many precision measurements. There are multiple mechanisms by which such noise is generated, many of which are poorly understood. Laser-cooled, trapped ions provide one of the most sensitive systems to probe electric-field noise at MHz frequencies and over a distance range 30 − 3000 µm from the surface. Over recent years numerous experiments have reported spectral densities of electric-field noise inferred from ion heating-rate measurements and several different theoretical explanations for the observed noise characteristics have been proposed. This paper provides an extensive summary and critical review of electric-field noise measurements in ion traps, and compares these experimental findings with known and conjectured mechanisms for the origin of this noise. This reveals that the presence of multiple noise sources, as well as the different scalings added by geometrical considerations, complicate the interpretation of these results. It is thus the purpose of this review to assess which conclusions can be reasonably drawn from the existing data, and which important questions are still open. In so doing it provides a framework for future investigations of surface-noise processes.

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Section: A Reduction Of Noisementioning

confidence: 99%

Ion-trap measurements of electric-field noise near surfaces

et al. 2015

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“…Moreover, channels for the delivery of atoms or ions into the cavity and the integration of trapping structures into the cavity may impose further constraints on the cavity length. In the case of ion-trap quantum computing [9], the dielectric mirrors forming the cavity can also distort the radio-frequency fields required for trapping the ion due to their electric susceptibility and due to surface charges if they are too close to the trap electrodes [10,11].…”

Section: Introductionmentioning

confidence: 99%

Cavities with nonspherical mirrors for enhanced interaction between a quantum emitter and cavity photons

Karpov

Horák

2022

Phys. Rev. A

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We propose a procedure for the significant enhancement of the strong coupling rate between photons in an optical cavity and a single quantum emitter, such as an atom, quantum dot or trapped ion. We show that specially designed, non-spherical mirrors can lead to cavity eigenmodes that exhibit a large field enhancement at the center of the cavity while inducing significantly less beam divergence, and therefore smaller round trip losses and higher cooperativity, than can be achieved by operating a spherical-mirror cavity in the near-concentric regime. We verify our designs using mode matching theory and discuss their robustness relative to different kinds of manufacturing deviations.

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“…Strong coupling between emitter and cavity photon can be realized by a small cavity volume and therefore by a very short optical cavity. However, for many realistic quantum setups the cavity mirrors cannot be placed too close to each other due to technical difficulties: for trapped ion systems, short cavities lead to electrical charging of the dielectric mirrors and to distortion of the radio frequency ion trapping fields [7]; for neutral atoms, short cavity lengths are limited by the requirement for delivery of atoms into the cavity and for optical side access [8,9] for cooling and trapping. Thus, optical cavities utilized in quantum optical device applications need to combine a strong coupling rate with low losses while keeping the mirrors sufficiently apart.…”

Section: Introductionmentioning

confidence: 99%

Evolutionary algorithm to design high-cooperativity optical cavities

Karpov

Horák

2022

New J. Phys.

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Using an evolutionary algorithm combined with a gradient descent (GD) method we design optical cavities with significantly enhanced strong coupling rates between cavity photons and a single quantum emitter. Our approach allows us to find specially designed non-spherical mirrors which lead to high-finesse cavity eigenmodes with large field enhancement at the center of the cavity. The method is based on adding consecutive perturbations to an initial spherical mirror shape using the GD method for optimization. We present mirror profiles which demonstrate higher cavity cooperativity than any spherical cavity of the same size. Finally, we demonstrate numerically how such a cavity enhances the operation frequency and purity of coupling a Ca+ ion to an optical fiber photon.

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Oxford ion-trap quantum computing project

Abstract: We describe recent progress in the development of an ion-trap quantum information processor. We discuss the choice of ion species and describe recent experiments on read-out for a ground-state qubit and photoionization trap loading.

Cited by 16 publications

References 15 publications

Ion-trap measurements of electric-field noise near surfaces

Ion-trap measurements of electric-field noise near surfaces

Cavities with nonspherical mirrors for enhanced interaction between a quantum emitter and cavity photons

Evolutionary algorithm to design high-cooperativity optical cavities

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