Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

A pair photon source for heralded single-photon - single-atom interaction

Albrecht Haase, Nicolás Piro, Jürgen Eschner, Morgan W. Mitchell

Published Jun 1, 2007• 0 citations

Abstract

We present the design and set-up of a narrow-bandwidth source of entangled photon pairs, which will allow us to address the transitions D3/2-P3/2 and D5/2-P3/2 in 40Ca+ ions at 850 and 854 nm wavelength, respectively. The source has been designed to emit photons with a high spectral power density into the absorption window of the Calcium ions, which has a bandwidth of ~20 MHz. The design has been chosen such that the produced photon rate and the output bandwidth can be varied independently, to be adapted to the experimental needs. Its application will be an experiment that studies methods of probabilistic entanglement of distantly trapped single atoms.

DOI: 10.1109/cleoe-iqec.2007.4386900

Related papers

An entangled photon source for resonant single-photon–single-atom interaction

Nicolás Piro, Albrecht Haase, Morgan W. Mitchell +1 more

We present the development and operation of a tunable, frequency-stabilized, narrow-bandwidth source of entangled photon pairs, which can be tuned to the two D–P transitions in Ca+ ions at 850 and 854 nm. The source is based on spontaneous parametric down-conversion in periodically poled KTiOPO4 (PPKTP) followed by tunable optical filters. Its output bandwidth of 22 MHz coincides with the absorption bandwidth of the calcium ions. Its spectral power density is 1.0 generated pairs (s MHz mW)−1. Here, we report details of the setup which was first described in Haase et al (2009 Opt. Lett. 34 55).

Journal of Physics B Atomic Molecular and Optical PhysicsMay 15, 200921 citations

Tunable narrowband entangled photon pair source for resonant single-photon single-atom interaction

Albrecht Haase, Nicolás Piro, Jürgen Eschner +1 more

We present a tunable, frequency-stabilized, narrow-bandwidth source of frequency-degenerate, entangled photon pairs. The source is based on spontaneous parametric downconversion in periodically poled KTiOPO(4). Its wavelength can be stabilized to 850 or 854 nm, thus allowing to address two transitions in (40)Ca(+) ions. Its output bandwidth of 22 MHz coincides with the absorption bandwidth of the calcium ions. Its spectral power density is 1.0 generated pairs/(s MHz mW).

arXiv:0808.1988Optics LettersDec 22, 200864 citations

Controlled absorption of heralded single photons by a single atom: towards entanglement distribution in quantum networks

Nicolas Piro Mastracchio

The interaction of single photons with single atoms is a fundamental process in quantum optics which manifests the quantum mechanical nature of light and matter. As an experimentally controlled process it enables the implementation of quantum technological applications, such as quantum information processing and quantum metrology. In the last decades, substantial progress has been attained to experimentally control and manipulate single atoms. For example, single or multiple ions can be stored in an ion trap and their quantum states can be controlled with great precision. At the same time, experimental techniques to generate and control single photons and entangled photon pairs have been widely developed. However, only modest progress has been attained in controlling the interaction of single atoms with sin~le photons. The aim of this thesis project was to experimentally study he absorption of single photons and entangled photons pairs by single trapped DCa· ions. To this end, a source of polarization-entangled photon pairs based on the process of spontaneous parametric down-conversion (SPDC) was designed and constructed . Generating photon pairs whose interaction with an atom can be controlled imposed stringent requirements on the bandwidth, tunability, stability and brightness of the source, making its setup much more complex than usual SPDC sources. In a parallel project, a set of two separate ion traps were built, capable of storing a single or a set of a few 4DCa· ions. he first part of the thesis documents the design, construction , operation and characterization of the entangled photon pair source. The characterization proves all the necessary requirements for the photons to interact with either of two transitions, D312 P312 and D5i2 P312 at 850 and 854 nm respectively, in 4DCa· One of the crucial requirements was to make the source bandwidth match the bandwidth of these transitions (22MHz). This was not straightforward since the typical emission bandwidths of the SPDC process is several orders of magnitude higher (1 05MHz). The ion trap setup is also briefly described. One of its crucial features is the inclusion of two high numerical-aperture objectives very close to the ion trap, allowing to enhance the interaction efficiency of the SPDC photons with the ion, and to efficiently collect the fluorescence light they emit. In a second part of the thesis, a concise description of the schemes and techniques used to detect the absorption of single photons by a single trapped ion is given, including a heoretical treatment of the methods used to analyze the data. he core part of the thesis describes the methods used to couple the entangled photon source to one of the ion traps, and explains the results obtained with the combined setup. First it shows how the source is configured to produce heralded single photons. It then presents experiments in which the absorption by a single ion of photons produced by the source is detected, and how these absorption events are time-correlated with the detection of the heralding photon. These experiments are performed under several conditions, with a growing level of control over the interaction process. Finally, two proof-of-principle experiments are presented. In the first one, the ion is pumped to polarization-sensitive Zeeman substates and the polarization dependence of the correlated absorption rate is observed. This is a first step toward more advanced experiments in which the polarization entanglemen of the photon pairs is transferred to the entanglement of one photon with one atom or to two distant atoms. A second experiment performs heralded single photon spectroscopy on a single ion, showing the expected frequency dependence of the absorption process. Finally, methods to extend these experiments to implement entanglement transfer from photons to atoms are outlined. In particular, it is shown how the efficiency of the source can be improved to make these experiments feasible.

Jan 1, 20102 citations

A Single Ion Interacting with Single Spontaneous Parametric Down-Conversion Photons

Nicolás Piro, Felix Rohde, Carsten Schuck +7 more

We present a tunable, frequency-stabilized, narrow-bandwidth source of frequency-degenerate, entangled photon pairs, which can address the two D-P transitions in 40Ca+ ions. We also demonstrate single ion-single photon interaction by the detection of quantum jumps.

Conference on Lasers and Electro-OpticsJan 1, 20090 citations

Single Atom – Single Photon Interfaces

Felix Rohde, Carsten Schuck, Markus Hennrich +7 more

In an experimental system of two distant ion traps we trap simultaneously strings of Ca+ ions and observe Hong-Ou-Mandel interference between their scattered photons. We also generate entangled photon pairs whose frequency and bandwidth are matched to an absorption line in the ions, and work towards heralded single photon – single ion interaction.

International Conference on Quantum InformationJan 1, 20080 citations

Interfacing single ions and single photons for quantum networks

Carsten Schuck

Experiments in quantum optics are motivated by fundamental questions about the quantum mechanical description of matter and light as well as by applications in quantum technologies such as quantum information processing. Exploiting the quantum character of both matter and light has turned out to be extremely rewarding for novel technological applications in the emerging fields of quantum communication and computation. Here we consider the implementation of quantum information technology with trapped ions and single photons, focusing on two key issues: the entanglement of distant atoms and the controlled interaction of a single photon with a single atom. This thesis describes the construction of a double ion trap apparatus including the necessary frequency-stabilized laser systems, and first experiments to investigate the generation of distant atomic entanglement, the implementation of a simple quantum network and controlled single-atom single-photon interaction. The experimental setup comprises two ion traps at a distance of one meter, which are independent but identical in construction. We introduce novel realizations of a photoionization method for calcium atoms, a laser frequency stabilization scheme and a radio frequency pulse sequencer. Linear Paul traps are used to load individual or strings of calcium ions. High-numerical aperture objectives mounted on sub-micrometer positioning systems allow us to address and manipulate a single ion with strongly focused light fields and collect the emitted fluorescence photons from a large solid angle. With these bidirectional single-atom single-photon interfaces the essential building blocks of a quantum network with atoms and photons are available. One of the main objectives we pursue with the double-trap apparatus is the generation of entanglement between ions in different traps, which is one of the key tasks in a quantum network. We compare single- and two-photon schemes for probabilistic entanglement creation and analyze how the performance of the schemes depends on photon detection efficiency. As a first step towards the experimental realization of such schemes we measure the second order correlation function of fluorescence photons emitted from two distant trapped ions. We observe high-contrast quantum (Hong-Ou-Mandel) interference, proving the indistinguishability of photons emitted from different ions, which is a prerequisite for the considered entanglement schemes. To investigate the interaction of single photons and a single atom in free space we combine the ion trap apparatus with a tunable, narrowband spontaneous parametric down-conversion source. The high-numerical aperture objectives allow us to efficiently couple bandwidth-tunable photons to a single trapped ion. Such atom-photon interaction at the single-particle level is the most fundamental process in quantum optics and lies literally at the focus of many experimental implementations of quantum information processing protocols and of studies of the (quantum) limits of matter -light interaction, which were so far restricted to weak coherent light fields. Here we observe individual atomic absorption events of one photon of an entangled pair by employing a quantum jump detection scheme. To characterize and control the interaction process we modify the spectral properties of the down conversion photons and perform single-photon spectroscopy of a single ion. To go beyond experiments with cohe rent fields we study temporal correlations between the absorption of photons from the spontaneous parametric down conversion source by a single ion and the detection of the corresponding partner photon. For the applied scheme we observe promising indications that the quantum correlations of photons produced in spontaneous parametric down conversion are preserved in the resonant interaction with a single atom. The implementation of more efficient atom-light coupling and entanglement transfer schemes with our apparatus is outlined.

Jan 1, 20103 citations