A high repetition rate experimental setup for quantum non-linear optics with cold Rydberg atoms

Hannes Busche,Simon W Ball,Paul Huillery

doi:10.1140/epjst/e2015-50338-3

Hannes Busche, Simon W Ball + Show 1 more

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https://doi.org/10.1140/epjst/e2015-50338-3

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Abstract

Using electromagnetically induced transparency and photon storage, the strong dipolar interactions between Rydberg atoms and the resulting dipole blockade can be mapped onto light fields to realise optical non-linearities and interactions at the single photon level. We report on the realisation of an experimental apparatus designed to study interactions between single photons stored as Rydberg excitations in optically trapped microscopic ensembles of ultracold 87Rb atoms. A pair of in-vacuum high numerical aperture lenses focus excitation and trapping beams down to 1 μm, well below the Rydberg blockade. Thanks to efficient magneto-optical trap (MOT) loading from an atomic beam generated by a 2D MOT and the ability to recycle the microscopic ensembles more than 20000 times without significant atom loss, we achieve effective repetition rates exceeding 110 kHz to obtain good photon counting statistics on reasonable time scales. To demonstrate the functionality of the setup, we present evidence of strong photon interactions including saturation of photon storage and the retrieval of non-classical light. Using in-vacuum antennae operating at up to 40 GHz, we perform microwave spectroscopy on photons stored as Rydberg excitations and observe an interaction induced change in lineshape depending on the number of stored photons.

Highlights

The European Physical Journal Special Topics excitation, strong optical non-linearities manifesting themselves in a suppression of transmission for increasing numbers of signal photons have been observed [8, 9].As a result of the non-linearity, highly non-classical states of light have been observed in optically thick media [10, 11] and by storing photons as long-lived collective Rydberg excitations in strongly confined volumes [12, 13]
We show that at low signal intensities trap loss is sufficiently weak to allow several 104 repetitions of typical experiments following a single magneto-optical trap (MOT) loading, which is a second crucial factor contributing to achieving high repetition rates
We give a short description of measures taken to achieve good electric field control, as well as on the implementation of three antennae inside the vacuum chamber to drive microwave transitions between Rydberg states at up to 40 GHz. An overview of both the laser system used to couple to Rydberg states as well as the single photon detection setup is presented, and we demonstrate Rydberg electromagnetically induced transparency (EIT) in a non-interacting regime

Summary

Introduction

As a result of the non-linearity, highly non-classical states of light have been observed in optically thick media [10, 11] and by storing photons as long-lived collective Rydberg excitations in strongly confined volumes [12, 13]. A single stored photon has been used to control the transmission of light in a cold atomic ensemble realising all-optical switching [19] and single photon transistors [20,21], as well as the conditional application of a π-phase shift [22]. Thanks to the long life-times and the tunability of the interaction, photon storage in Rydberg states provides a convenient platform for these applications and future experiments in the context of optical quantum information processing

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