# Publications

## Cavity Induced Interfacing of Atoms and Light

Chapter in ,

A Kuhn

This chapter introduces cavity-based light-matter quantum interfaces, with a single atom or ion in strong coupling to a high-finesse optical cavity. We discuss the deterministic generation of indistinguishable single photons from these systems; the atom-photon entanglement intractably linked to this process; and the information encoding using spatio-temporal modes within these photons. Furthermore, we show how to establish a time-reversal of the aforementioned emission process to use a coupled atom-cavity system as a quantum memory. Along the line, we also discuss the performance and characterisation of cavity photons in elementary linear-optics arrangements with single beam splitters for quantum-homodyne measurements.

## Photonic Quantum Logic with Narrowband Light from Single Atoms

arXiv (2015)

A Holleczek, O Barter, A Rubenok, J Dilley, PBR Nisbet-Jones, G Langfahl-Klabes, GD Marshall, C Sparrow, JL O'Brien, K Poulios, AR Kuhn, JCF Matthews

We demonstrate quantum logic using narrow linewidth photons that are produced under nearly perfect quantum control from a single Rb atom strongly coupled to a high-finesse cavity. We use a controlled- NOT gate integrated into a photonic chip to entangle these photons, and we observe non-classical correlations between events separated by periods exceeding the travel time across the chip by three orders of magnitude. This enables quantum technology that will use the properties of both narrowband single photon sources and integrated quantum photonics, such as networked quantum computing, narrow linewidth quantum enhanced sensing and atomic memories.

## Cavity Induced Interfacing of Atoms and Light

in Engineering the Atom-Photon Interaction: Controlling Fundamental Processes with Photons, Atoms and Solids, Springer (2015) 1
Part of a series from Nano Optics and Nano Photonics

AR Kuhn

This chapter introduces cavity-based light-matter quantum interfaces, with a single atom or ion in strong coupling to a high-finesse optical cavity. We discuss the deterministic generation of indistinguishable single photons from these systems; the atom-photon entanglement intractably linked to this process; and the information encoding using spatio-temporal modes within these photons. Furthermore, we show how to establish a time-reversal of the aforementioned emission process to use a coupled atom-cavity system as a quantum memory. Along the line, we also discuss the performance and characterisation of cavity photons in elementary linear-optics arrangements with single beam splitters for quantum-homodyne measurements.

## Qubits, qutrits, and ququads stored in single photons from an atom-cavity system

ADVANCES IN PHOTONICS OF QUANTUM COMPUTING, MEMORY, AND COMMUNICATION VIII 9377 (2015)

A Holleczek, O Barter, G Langfahl-Klabes, A Kuhn

## Fast algorithms for generating binary holograms

ArXiv (2014)

D Stuart, O Barter, A Kuhn

We describe three algorithms for generating binary-valued holograms. Our methods are optimised for producing large arrays of tightly focussed optical tweezers for trapping particles. Binary-valued holograms allow us to use a digital mirror device (DMD) as the display element, which is much faster than other alternatives. We describe how our binary amplitude holograms can be used to correct for phase errors caused by optical aberrations. Furthermore, we compare the speed and accuracy of the algorithms for both periodic and arbitrary arrangements of traps, which allows one to choose the ideal scheme depending on the circumstances.

## Single Emitters in Isolated Quantum Systems

in , 45 (2013) 467-539

GS Solomon, C Santori, A Kuhn

## Quantum networking with time-bin encoded qu-d-its using single photons emitted on demand from an atom-cavity system

2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013 (2013)

A Holleczek, O Barter, PBR Nisbet-Jones, J Dilley, A Kuhn

One of today's challenges to realize computing based on quantum mechanics is to reliably and scalably encode information in quantum systems. This is particularly crucial when dealing with promising approaches such as linear optics quantum computing (LOQC) in photonic circuits [1,2]. Although this method is in principle scalable, in practice it is limited by the probabilistic nature of spontaneous parametric down-conversion (SPDC) sources used to seed the circuits. © 2013 IEEE.

## Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

New Journal of Physics 15 (2013) 053007

PBR Nisbet-Jones, J Dilley, A Holleczek, O Barter, A Kuhn

Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing, which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom–cavity system fulfil these requirements. Within their 500 ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.

## Quantum networking with time-bin encoded qu-d-its using single photons emitted on demand from an atom-cavity system

2013 CONFERENCE ON AND INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE LASERS AND ELECTRO-OPTICS EUROPE (CLEO EUROPE/IQEC) (2013)

A Holleczek, O Barter, PBR Nisbet-Jones, J Dilley, A Kuhn, IEEE

## Single-photon absorption in coupled atom-cavity systems

PHYSICAL REVIEW A 85 (2012) ARTN 023834

J Dilley, P Nisbet-Jones, BW Shore, A Kuhn

## Control and manipulation of cold atoms in optical tweezers

NEW JOURNAL OF PHYSICS 14 (2012) ARTN 073051

C Muldoon, L Brandt, J Dong, D Stuart, E Brainis, M Himsworth, A Kuhn

## Quantum memories for single photons from cavity-QED

Optics InfoBase Conference Papers (2011)

A Kuhn, P Nisbet, J Dilley, G Langfahl-Klabes, M Himsworth

## Three Dimensional Raman Cooling using Velocity Selective Rapid Adiabatic Passage

Chapter in ,

A Kuhn, H Perrin, W Hänsel, C Salomon

We present a new and efficient implementation of Raman cooling of trapped atoms. It uses Raman pulses with an appropriate frequency chirp to realize a velocity selective excitation through a rapid adiabatic passage. This method allows to address in a single pulse a large number of non zero atomic velocity classes and it produces a nearly unity transfer efficiency. We demonstrate this cooling method using cesium atoms in a far-detuned crossed dipole trap. Three-dimensional cooling of $1 \times 10^{5}$ atoms down to $2 \mu$K is performed in 100 ms. In this preliminary experiment the final atomic density is $1.3\times 10^{12}$ at/cm$^3$ (within a factor of 2) and the phase-space density increase over the uncooled sample is 20. Numerical simulations indicate that temperatures below the single photon recoil temperature should be achievable with this method.

## Single-Photon Absorption in Coupled Atom-Cavity Systems

ArXiv (2011)

J Dilley, P Nisbet-Jones, BW Shore, A Kuhn

We show how to capture a single photon of arbitrary temporal shape with one atom coupled to an optical cavity. Our model applies to Raman transitions in three-level atoms with one branch of the transition controlled by a (classical) laser pulse, and the other coupled to the cavity. Photons impinging on the cavity normally exhibit partial reflection, transmission, and/or absorption by the atom. Only a control pulse of suitable temporal shape ensures impedance matching throughout the pulse, which is necessary for complete state mapping from photon to atom. For most possible photon shapes, we derive an unambiguous analytic expression for the shape of this control pulse, and we discuss how this relates to a quantum memory.

## Highly Efficient Source for Indistinguishable Photons of Controlled Shape

ArXiv (2011)

P Nisbet, J Dilley, A Kuhn

We demonstrate a straightforward implementation of a push-button like single-photon source which is based on a strongly coupled atom-cavity system. The device operates intermittently for periods of up to 100 microseconds, with single-photon repetition rates of 1.0 MHz and an efficiency of 60 %. Atoms are loaded into the cavity using an atomic fountain, with the upper turning point near the cavity's mode centre. This ensures long interaction times without any disturbances induced by trapping potentials. The latter is the key to reaching deterministic efficiencies as high as obtained in probabalistic photon-heralding schemes. The price to pay is the random loading of atoms into the cavity and the resulting intermittency. However, for all practical purposes, this has a negligible impact.

## Highly Efficient Source for Indistinguishable Photons of Controlled Shape

New Journal of Physics 13 (2011) 103036

PBR Nisbet-Jones, J Dilley, A Kuhn

We demonstrate a straightforward implementation of a push-button like single-photon source which is based on a strongly coupled atom-cavity system. The device operates intermittently for periods of up to 100 microseconds, with single-photon repetition rates of 1.0 MHz and an efficiency of 60 %. Atoms are loaded into the cavity using an atomic fountain, with the upper turning point near the cavity's mode centre. This ensures long interaction times without any disturbances induced by trapping potentials. The latter is the key to reaching deterministic efficiencies as high as obtained in probabalistic photon-heralding schemes. The price to pay is the random loading of atoms into the cavity and the resulting intermittency. However, for all practical purposes, this has a negligible impact.

## Highly efficient source for indistinguishable single photons of controlled shape

NEW JOURNAL OF PHYSICS 13 (2011) ARTN 103036

PBR Nisbet-Jones, J Dilley, D Ljunggren, A Kuhn

## EIT-based quantum memory for single photons from cavity-QED

APPLIED PHYSICS B-LASERS AND OPTICS 103 (2011) 579-589

M Himsworth, P Nisbet, J Dilley, G Langfahl-Klabes, A Kuhn

## Spatial light modulators for the manipulation of individual atoms

APPLIED PHYSICS B-LASERS AND OPTICS 102 (2011) 443-450

L Brandt, C Muldoon, T Thiele, J Dong, E Brainis, A Kuhn

## Control and Manipulation of Cold Atoms in Optical Tweezers

ArXiv (2011)

C Muldoon, L Brandt, J Dong, D Stuart, E Brainis, M Himsworth, A Kuhn

Neutral atoms trapped by laser light are amongst the most promising candidates for storing and processing information in a quantum computer or simulator. The application certainly calls for a scalable and flexible scheme for addressing and manipulating the atoms. We have now made this a reality by implementing a fast and versatile method to dynamically control the position of neutral atoms trapped in optical tweezers. The tweezers result from a spatial light modulator (SLM) controlling and shaping a large number of optical dipole-force traps. Trapped atoms adapt to any change in the potential landscape, such that one can re-arrange and randomly access individual sites within atom-trap arrays.