PDOC - Retour Postdoctorants

Spins in solid for MEtrology and QUantum Information processing – SMEQUI

Spins in Solid for Quantum Metrology and Quantum Information

Over the past twenty years, remarkable progress has been made in isolating single quantum systems and controlling the coupling to their environment. A lot of efforts were undertaken using ultra-cold single trapped atoms for reaching these goals. Inspired by these amazing developments, nitrogen vacancy (NV) defects in diamonds are now reaching an unprecedented degree of control that will enable most of these above experiments to be realised in a solid state environment.

COHERENT EXCHANGE OF SPINS WITH LIGHT FIELDS

The proposed project is both timely and ambitious in that it will benefit from the expertise in the field of cold single ion physics and also proposes to promote NV centres to a level that may surpass these systems. To achieve such ambitious tasks, several technical challenges are going to be tackled. <br />The first part of the SMEQUI project aims at demonstrating fundamental quantum metrology effects with several nuclear spins, such as the influence of vacuum fields on the spectral properties of NV centres (negatively charged NV, on the zero phonon line (ZPL) at 637 nm) and the precise measurement of the microwave transition at 2.8 GHz for solid state atomic clocks. <br /> <br />The second part of the SMEQUI project belongs to a broad area of research which investigates the physics underlying exchange of quanta between light and matter. Owing to their long lifetime and the possibility of measuring their internal states, NV centres spin states are ideally suited for long-distance quantum communication. We plan to demonstrate probabilistic entanglement of two NV centres, to demonstrate scattering of light by entangled NV centres and to demonstrate efficient deterministic coupling to single NV centres. <br />

In the course of these 3 years, the more advanced technical aspects will be developed in parallel to benchmark measurements. The experiments that we are going to realise concern single centres at low temperature where already important observations, such as the estimation of the frequency stability of the 2.8 GHz transition can be realised. For the most part of the project, a cryostat will however be needed. Quantum optical measurements at low temperature will be performed with siV centers.

We have designed a novel high NA cryostat which will be delivered in a few months and observed efficient luminescence from SiV centers in nano diamonds.

These nano diamonds containing single SiV centers will enable direct absorption of light form a laser field as well as demonstration of QED from single atoms in the solid state.

1. Light shift modulated photon echoes. T. Chanelière et G. Hétet, Optics Letters 40(7) 1294-1297 (2015)

2. Spin wave Diffraction Control and Read-out with a Quantum Memory for Light G. Hétet et D. Guery-Odelin, A paraître dans New Journal of Physics (2015).

Over the past twenty years, remarkable progress has been made in isolating single quantum systems and controlling the coupling to their environment. A lot of efforts were undertaken using ultra-cold single trapped atoms for reaching these goals. Amongst the most recent trailblazing experimental realisations, one can list the demonstration of 14 entangled ions, their use as quantum simulators, the generation of long distance entanglement between atoms, the realisation of ultra-stable clocks and the observation of very pristine quantum-electrodynamical effects. Inspired by these amazing developments, nitrogen vacancy (NV) defects in diamonds are now reaching an unprecedented degree of control that will certainly enable most of these above experiments to be soon realised in a solid state environment.

We intend to transfer part of the knowledge developed over the past decades in the field of single ultra-cold atoms to NV centres in diamonds, with the prospect of being in a position to perform fundamental investigations of quantum electrodynamics and metrology and for operations that are needed for quantum communication in the solid state. Along this project, the tools to realize hybrid platforms comprising of spins in diamonds interacting with single photons will indeed be developed together with investigations of fundamental quantum optical processes.

A first part of the research proposal will be devoted to what may be coined “vacuum metrology” in the solid state phase. We will use NV centres in diamonds to undertake original experiments that aim to observe vacuum effects with a single boundary condition, such as the modification of the Lamb shift, of the spontaneous emission rate and of the vacuum Rabi coupling. We also intend to measure super-radiance and the associated collective Lamb shifts using two or more NV centres well localised within the same or between separated diamond host(s). As part of these metrology goals, improvement in the precision of the microwave transition for applied metrology will be performed. Although atomic clocks are widely used for satellite communication, high-bandwidth wireless communication and other navigation techniques, artificial atoms in solid state systems should also be investigated, as they have the potential to greatly simplify their functionality.

The second part of the proposal will be devoted to long distance exchange of quanta between photons and atoms in a crystal. We intend to make use of the scalability of NV centres to demonstrate entanglement and scattering of light by several spins using protocols that enhance the networking efficiency between remote spins in a crystal. As part of this second line of research, we also wish to investigate absorption and phase shifts of a single photon by a few NV centres. Realising such a deterministic coupling between light and matter will provide a unique tool to investigate cavity effects with a single atomic spin as a mirror or a novel read-out scheme for the NV centre microwave state.

Alongside with these two parts of the project, we envision making use of the scalability offered by the single NV centre doping technology to increase the interaction with light fields. Many NV centers will indeed be inserted at desired locations within the diamond lattice. The collective coupling strength to light modes will thus boost the efficiency of the quantum metrology and communication aspects of the project and offer other perspectives for efficient quantum simulations and light storage for quantum networks.

Our SMEQUI proposal will contribute to solving issues that quantum technology addresses and deals with timely subjects such as components for quantum networks, light-matter interfaces in the solid state and very fundamental opened questions in quantum optics.



Project coordinator

Monsieur Gabriel HÉTET (Laboratoire Aimé Cotton)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LAC Laboratoire Aimé Cotton

Help of the ANR 511,828 euros
Beginning and duration of the scientific project: November 2013 - 42 Months

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