We design and grow rare earth doped crystals in which we aim at controlling optical and spin non-classical states. These materials, produced in the form of bulk and nanostructured single crystals, show extremely long-lived quantum states at low temperature. This unique property in the solid state enables us to address a broad range of applications, from quantum information processing and communication, to spectral analysis and medical imaging. 
We belong to the Material for Photonics and Opto-Electronics team of the Institut de Recherche de Chimie Paris. The Institute is a joint unit between Chimie ParisTech graduate school and the Centre National de la Recherche Scientifique.

To meet the high demands of quantum technologies, systems with multiple quantum degrees of freedom that can be addressed by light and coupled to other quantum systems in hybrid architectures are strongly needed. We aim at building such devices from solid-state nanostructures that exploit the uniquely narrow optical transitions of rare earth ions. We expect these devices to have a strong impact on quantum communication, quantum sensing and quantum opto-electronics.

A key point of nanoscale quantum systems is to preserve long-lived quantum states despite the larger environmental noise present at surfaces and interfaces, or originating in additional defects.

We develop rare earth doped nanocrystals and thin films with high crystalline quality and purity by bottom-up approaches based on soft chemistry and other techniques. The combination of structural characterization and optical spectroscopy allows us to synthesize nanostructures with low perturbations to the optical quantum states. High performance materials can be used to build hybrid devices, where ions like europium or erbium can provide a quantum interface between light and other quantum systems.


Quantum memories are devices capable of faithfully storing photonic quantum states into matter. Their applications include long distance quantum cryptography and more generally quantum networks. Rare-earth ions are promising candidates for solid-state quantum memories, because of the long-lived superposition states of their optical and spin transitions. 

We investigate crystals with multiple degrees of freedom, in which quantum states can be transferred between optical, electron and nuclear spins. In this way, quantum interfaces can be achieved between propagating quantum bits (optical and microwave photons), and long-lived quantum bits (nuclear spins). We aim at increasing quantum states lifetimes by material design and control techniques based on external electromagnetic fields. We also study schemes for improved quantum memories in terms of storage times, efficiency or bandwidth.
High temperature crystal growth techniques are used to produce state of the art samples doped with rare earth ions like europium (optical memories) or neodymium (optical and microwave memories). Optical coherent and high resolution spectroscopy, spectral hole burning, as well as optically detected magnetic resonance allow us to determine all relevant parameters and investigate memory schemes.  


Single crystals for quantum memories

Nanostructures for hybrid quantum systems

Spectral analysis 

Long-lived quantum states translate into narrow linewidths. Thus, rare earth doped crystals can exhibit extremely narrow optical linewidths, in the range of a few kHz or even a few 100 Hz in some cases. This enables highly selective spectral filtering that has applications in acousto-optic medical imaging, laser frequency stabilization for metrology or wireless and radar signal analysis. 

We develop crystals in which a strong optical absorption line can be tailored to create narrow transmission windows. These features, called spectral holes, can then be used as a frequency reference or a filter. As an example, for deep tissue imaging in the infrared, we grow thulium doped crystals that can filter light that interacted with ultrasound waves. In this way, the optical signal provides images that carry additional information compared to ultrasound only diagnostic. We also investigate transparent ceramics as an alternative to single crystals. These materials can be produced in large volumes and complex shapes that can benefit to spectral analysis applications, while showing linewidths nearly as narrow as the best single crystals. 




Group activity: escape game

November 19, 2019

Had a great evening at the escape game in St Michel trying to figure out how to repair a subway train...

The metro game

PhD defense of Marion Scarafagio

October 24, 2019

Marion Scarafagio has successfully defended her PhD work. Congratulations to her! She gave a presentation on Growth and characterization of nanometer-thin films doped with rare-earth for quantum technologies. Her research was funded by the NanoQtech European project.


New paper in Physical Review B on Pr:Y2O3 nanoparticles

October 09, 2019

We investigate the potential for optical quantum technologies of Pr3+:Y2O3 in the form of monodisperse spherical nanoparticles of 150-400 nm in size. We measured optical ioptical homogeneous linewidths of up to 108 kHz and spin T2 of up to 880µs. This value is even higher than that measured for bulk Pr3+-doped crytals. This indicates that this material system is a promising candidate for integration into quantum devices, in particular for realizing spin-photon interfaces emitting indistinguishable single photons.

D. Serrano, C. Deshmukh, S. Liu, A. Tallaire, A. Ferrier, H. de Riedmatten, P. Goldner, Coherent optical and spin spectroscopy of nanoscale Pr3+:Y2O3, Physical Review B, 100 (2019) 144304.


PhD defense of Alexandre Fossati

September 19, 2019

Alexandre Fossati has successfully defended his PhD on September the 20th. Congratulations to him! His work concerned the synthesis and optical properties of Y2O3 nanoparticles doped with rare-earth ions within the context of optical quantum technologies. His research was funded by the NanoQtech European project.

Paper on naodiamonds in ACS applied Nanomaterials

September 30, 2019

We report on the synthesis of loose NDs by high-power plasma chemical vapor deposition (CVD) without the need of a seeded substrate for nucleation. The as-grown NDs, dispersed in solution, exhibit high crystalline quality and low impurity background. A tunable amount of nitrogen-vacancy (NV) centers is introduced thanks to moderate N2 additions during growth. We then thoroughly assess the optical properties of the produced nanodiamonds. Thanks to this synthesis approach, large-scale production of CVD NDs with a wide tunability of their chemical composition is achieved, paving the way to their use as a platform for exploring quantum sensing applications.

A. Tallaire, O. Brinza, M. De Feudis, A. Ferrier, N. Touati, L. Binet, L. Nicolas, T. Delord, G. Hétet, T. Herzig, S. Pezzagna, P. Goldner, J. Achard, Synthesis of Loose Nanodiamonds Containing Nitrogen-Vacancy Centers for Magnetic and Thermal Sensing, ACS Applied Nano Materials, 2 (2019) 5952-5962.


CNRS activity report

August 25, 2019

Our work on Ytterbium for quantum memories has been highlighted in the main 2018 CNRS activity report in the field "Ingénierie et numérique".

Check it out here!


And the associated paper in Nature Materials.

CNRS-INC news on quantum memories

July 24, 2019

Recent works from our group on quantum memories and microwave to optical photon conversion are highlighted on the CNRS-INC webpage (Institut de Chimie). This follows our recent publications in Physcial Review Letters.

Summer school at Karlsruhe Institute of Technology

July 11, 2019

Our team has participated to the summer school organized by KIT. It provided an introduction to quantum computing and quantum networks with a focus on implementations with optically adressable rare earth ion spins. This event is organized within the framework of the European project SQUARE. The presentations and discussions ended by a very instructive lab tour of KIT facilities (David Hunger's group).

Best oral presentation price - Marion Scarafagio

June 27, 2019

Congratulations to Marion, last year PhD student in our group who won the price for the best oral presentation at her session in the EuroCVD conference that was held in Luxembourg from 24-28 june 2019. Her talk was entitled: Eu3+ or Er3+ doped Y2O3 thin films grown by ALD with optimized properties for quantum technologies and was part of her work in the European project NanoQtech.

New paper in Physical Review Letters

June 18, 2019

Efficient and reversible optical to microwave transducers are required for entanglement transfer between superconducting qubits and light in quantum networks. To this end, we investigate spin coherence in an optically excited state of an Er3+: Y2SiO5 crystal at temperatures from 1.6 to 3.5 K and found spin coherence and population lifetimes of up to 1.6  μs and 1.2 ms by optically detected spin echo experiments. We eventually propose a quantum transducer scheme that exploits the advantages offered by spin states of the optically excited electronic energy levels.


S. Welinski, P.J.T. Woodburn, N. Lauk, R.L. Cone, C. Simon, P. Goldner, C.W. Thiel, Electron Spin Coherence in Optically Excited States of Rare-Earth Ions for Microwave to Optical Quantum Transducers, Physical Review Letters, 122 (2019) 247401.


Seminar by John Bartolomew

Dr John Bartolomew who is currently a postdoctoral research fellow in Prof Faraon's group at Caltech (and a former member of our group - 2015-2016) gave a seminar at IRCP Chimie-Paristech to present his latest results on quantum nanophotonics using rare-earth ions in crystalline materials.

New NanoQtech Newsletter Issue 4

All the latest news about the European project NanoQtech !

1. Quantum sensing and how it shall change the world

2. A Ph. D. thesis explained in 180 seconds 

3. NanOQTech's actors: Dr. Klaas-Jan Tielrooij, ERC starting grant laureate      

4. Events: national day of scientific training in chemistry

5. Latest publications

Visit here

New paper in Physical Review Applied

June 05, 2019

Using superconducting resonators patterned directly on Y2SiO5 we investigate the use of Y2SiO5 as an alternative to sapphire or silicon substrates for superconducting-hybrid-device fabrication. A NbN resonator with frequency 6.008 GHz and low-power quality factor Q≈400000 is fabricated on a Y2SiO5 substrate doped with isotopically enriched 145Nd. These results demonstrate that Y2SiO5 is an excellent substrate for low-loss, high-Q microwave resonators, especially in applications for coupling to optically accessible rare-earth spins.

G. Dold, C.W. Zollitsch, J. O’Sullivan, S. Welinski, A. Ferrier, P. Goldner, S.E. de Graaf, T. Lindström, J.J.L. Morton, High-Cooperativity Coupling of a Rare-Earth Spin Ensemble to a Superconducting Resonator Using Yttrium Orthosilicate as a Substrate, Physical Review Applied, 11 (2019) 054082.


New paper in Journal of Physical Chemistry C

May 14, 2019

In this new paper we studied the optical properties of thin Eu or Er doped Y2O3 films grown by Atomic Layer Deposition. We demonstrate that by optimizing the deposition conditions and using appropriate annealing post treatments narrow inhomogeneous lines can be obtained even for films as thin as 11 nm while 1.5ms lifetime is measured for Er ions. These results validate this materialfilms as a suitable platform for photonics applications and provides the first building blocks toward the development of more complex devices for quantum sensing or hybrid structures.

M. Scarafagio, A. Tallaire, K.-J. Tielrooij, D. Cano, A. Grishin, M.-H. Chavanne, F.H.L. Koppens, A. Ringuedé, M. Cassir, D. Serrano, P. Goldner, A. Ferrier, Ultrathin Eu- and Er-Doped Y2O3 Films with Optimized Optical Properties for Quantum Technologies, The Journal of Physical Chemistry C, 123 (2019) 13354-13364.


CQSD bowling event

May 12, 2019

Great evening competing at bowling! And the winners are ... Shuping and Alban!

Alexandre @ "My PhD in 180 seconds"

April 04, 2019

Congratulations to Alexandre Fossati who participated to the national event "My PhD in 180 seconds". He shared our research activities to a broad audience. He was acclaimed for his lively explanation and went through to the semi-finals! To understand all about the dance of rare-earth ions, have a look at this video:


New paper in PRB

January 14, 2019

Rare-earth ion-doped crystals are promising systems for quantum communication and quantum information processing. In particular, paramagnetic rare-earth centers can be utilized to realize quantum coherent interfaces simultaneously for optical and microwave photons. In this paper, we study hyperfine and magnetic properties of a Y2SiO5 crystal doped with 171Yb3+ ions. This isotope is particularly interesting since it is the only rare–earth ion having electronic spin S = 1/2 and nuclear spin I =1/2 , which results in the simplest possible hyperfine  level structure. In this work, we determine the hyperfine tensors for the ground and excited states on the optical 2F7/2(0) ←→ 2F5/2(0) transition by combining spectral hole burning and optically detected magnetic resonance techniques. These results pave the way for realizing solid-state optical and microwave quantum memories based on a 171Yb3+:Y2SiO5 crystal. 


A. Tiranov, A. Ortu, S. Welinski, A. Ferrier, P. Goldner, N. Gisin, and M. Afzelius, "Spectroscopic study of hyperfine properties in 171Yb3+:Y2SiO5," Phys. Rev. B 98, 195110 (2018).

Paper in New Journal of Physics

February 24, 2019

We report on the coupling of the emission from a single europium-doped nanocrystal to a fiber-based microcavity under cryogenic conditions. In particular, we couple an isolated nanocrystal to an optical microcavity and perform cavity-enhanced spectroscopy by resonantly coupling a cavity mode to a selected transition. We detect the fluorescence from an ensemble of few ions in the regime of power broadening and observe an increased fluorescence rate consistent with Purcell enhancement. The results represent an important step towards the efficient readout of single rare earth ions with excellent optical and spin coherence properties.


B. Casabone, J. Benedikter, T. Hümmer, F. Oehl, K. de O. Lima, T. W. Hänsch, A. Ferrier, P. Goldner, H. de Riedmatten, and D. Hunger, "Cavity-enhanced spectroscopy of a few-ion ensemble in Eu 3+:Y 2O 3," New J. Phys. 20, 095006–9 (2018).

Paper in RSC Advances

November 05, 2018

Rare earth doped nanoparticles with sub-wavelength size can be coupled to optical micro- or nano-cavities to enable efficient single ion readout and control, a key requirement for quantum processors and high- fidelity single-ion quantum memories. However, producing small nanoparticles with good dispersion and exploitable optical coherence properties, another key aspect for these applications, is highly challenging by most synthesis and nano-fabrication methods. We report here on the wet chemical etching of Eu3+:Y2O3 nanoparticles and demonstrate that a controlled size reduction down to 150 nm, well below the wavelength of interest, 580 nm, can be achieved.  Furthermore, this method allows maintaining long optical coherence lifetimes (T2): the 12.5 ms and 9.3 ms values obtained for 430 nm initial particles and 150 nm etched particles respectively, revealing a broadening of only 10 kHz after etching. These values are the longest T2 values reported for any nanoparticles.


S. Liu, D. Serrano, A. Fossati, A. Tallaire, A. Ferrier, and P. Goldner, "Controlled size reduction of rare earth doped nanoparticles for optical quantum technologies," RSC Advances 8, 37098–37104 (2018).

PhD defense of Sacha Welinski

December 05, 2018

Sacha Welinski has successfully defended his PhD work entitled "Paramagnetic-rare-earth-doped single crystals for Quantum Information Processing" on December the 6th. Congratulations to him!

See abstract here

ASTERIQS european project Kick-off meeting

October 14, 2018

Advancing Science and Technology through diamond Quantum Sensing

The kick-off meeting of the ASTERIQS project has been held in IRCP Chimie ParisTech on October 15th and 16th. ASTERIQS aims at exploring the properties of Nitrogen-Vacancy centres in diamond and develop new sensors and technologies based on the peculiar properties of this material system.

The consortium that gathers 22 partners including academics and industries received a 10 M€ funding by the European commission within the Quantum flagship initiative. It is coordinated by T. Debuisschert from Thales.

See here

SQUARE european project Kick-off meeting

October 07, 2018

Scalable rare-earth ion quantum computing nodes

​The kick-off meeting of the european project SQUARE was held in Karlsruhe on 8th and 9th of October. The goal of SQUARE is to establish individually addressable rare earth ions as a basic building block for scalable quantum technologies. In particular, the functional elements of an optically readable multiqubit quantum register are to be demonstrated and building blocks of a quantum network realized.

SQUARE is located in the basic research segment of the flagship and is supported by 3 million euros for 3 years. It comprises a consortium of six international scientific groups from Arhus (Denmark), Lund (Sweden), Barcelona (Spain), Paris (France), Stuttgart and Karlsruhe, as well as two companies Thales (France) and Attocube (Germany). The project is coordinated by Professor David Hunger of the Karlsruhe Institute of Technology (Germany).

See here

Paper in Nature Materials

August 20, 2018

Solid-state electronic spins are extensively studied in quantum information science, as their large magnetic moments offer fast operations for computing and communication, and high sensitivity for sensing. However, electronic spins are more sensitive to magnetic noise, but engineering of their spectroscopic properties, for example, using clock transitions and isotopic engineering, can yield remarkable spin coherence times. Here we demonstrate simultaneously induced clock transitions for both microwave and optical domains in an isotopically purified171Yb3+:Y2SiO5 crystal, reaching coherence times of greater than 100 μs and 1 ms in the optical and microwave domains, respectively. 


A. Ortu, A. Tiranov, S. Welinski, F. Fröwis, N. Gisin, A. Ferrier, P. Goldner, and M. Afzelius, "Simultaneous coherence enhancement of optical and microwave transitions in solid-state electronic spins," Nat. Mater. 17, 1–6 (2018).


Link to the CNRS press release.

Paper in Nature Communications: All-optical control of long-lived nuclear spins in rare-earth doped nanoparticles

May 29, 2018

Nanoscale systems that coherently couple to light and possess spins offer key capabilities for quantum technologies. However, an outstanding challenge is to preserve properties, and especially optical and spin coherence lifetimes, at the nanoscale. We report optically controlled nuclear spins in rare-earth naoparticles with long coherence lifetimes of 2.9 ms at 5 K which is comparable to those obtained in bulk rare-earth crystals. These results open the way to providing quantum light-atom-spin interfaces with long storage time within hybrid architectures.


"All-optical control of long-lived nuclear spins in rare-earth doped nanoparticles" by D. Serrano, J. Karlsson, A. Fossati, A. Ferrier and P. Goldner. Nature Communications 9, 2127 (2018)

Links to the CNRS and SIRTEQ news.

Visiting researchers

May 11, 2018

We had the great pleasure to welcome in March and April, Dr. Charles Thiel, Montana State University, USA (picture),

Dr. Nathalie Kunkel, Technical University of Munich, Germany and Dr. Mikael Afzelius, University of Geneva, Switzerland.

We worked on different topics ranging from spectral hole burning and photon echoes to electron-phonon coupling in new hydride materials. 

NanOQTech project - Second Newsletter released

April 01, 2018

The second newsletter of the European project NanOQTech has just been released. An interview of Hugues de Riedmatten who was recently awarded is available in this issue.

Newsletter-Issue 2

More about NanOQTech here.

Paper in ZAAC: Recent Advances in Rare Earth Doped Inorganic Crystalline Materials for Quantum Information Processing

April 01, 2018

This review focuses on progress in the design of non-single-crystalline materials for quantum technologies as well as very recent milestones that were reached using single crystals.

The paper appears featured on the front cover.

Recent Advances in Rare Earth Doped Inorganic Crystalline Materials for Quantum Information Processing- N. Kunkel, P. Goldner, ZAAC 644, (2018) p65

Paper in Physical Review B: Coherent spin dynamics of ytterbium ions in yttrium orthosilicate

February 14, 2018

Rare-earth spins in optical crystals like yttrium orthosilicate (YSO) are of much interest for providing coherent interfaces with both microwave and optical photons. Here, we study the spin dynamics of a new system, Yb in YSO, which has good optical properties and strong hyperfine coupling to the 171Yb (spin-1/2) and 173Yb (spin-5/2) isotopes. The results demonstrate long coherence times for both the electron and nuclear spins (~1 ms). Employing a range of pulsed electron spin resonance measurements as well as comparison with relevant theory, the study elucidates a number of spin relaxation and decoherence mechanisms at work.

The paper has been labeled as "Editor's selection".

Hee-Jin Lim, Sacha Welinski, Alban Ferrier, Philippe Goldner, and J. J. L. Morton Phys. Rev. B 97, 064409 (2018)

Seminars in Munich and Madrid

December 23, 2017

Philippe presented four seminars in November and December 2017 on rare earth doped crystals and nanostructure for quantum technologies. They took place at the Autonomous University of Madrid, Department of Physics of Materials, the Technical University of Munich, Department  of Chemistry, and the Ludwig-Maximilian University of Munich, Department of Chemistry. 

Conférence RAFALD 2017

November 06, 2017

We participated to the national workshop on Atomic Layer Deposition in Montpellier. Marion gave a talk to present her results on the ALD growth of yttrium oxide thin films doped with rare-earth ions for quantum technologies.  

Science Fair 2017

October 14, 2017

Our team participated to the Science Fair again this year. We were pleased to share our work to a non-scientific public and show some examples of luminescence in crystals and nanoparticles...

New paper in Journal of Luminescence: Sc-doped YAG ceramics

October 09, 2017

Opaque ceramics are very attractive because they offer ease and low cost of fabrication and enable the study of a larger range of composition compared to single crystals. We show that Sc doping can be used to increase the inhomogeneous broadening without impacting the coherence properties and spectral hole persistence. This controlled disorder therefore provides larger bandwidth for signal processing applications such as spectral analyzers and quantum information processing.

Cathodoluminescence measurement in clean room (Univ. Paris 13)

September 27, 2017

We participated to a measurement session of our thin oxide films using a cathodoluminescence instrument available in the clean room of University Paris 13 (collaboration LSPM).

National Days of Crystals for Optics

September 06, 2017

Our team participated to the National Days of Crystals for Optics (JNCO-2017) that was organized by the CMDO-CNRS network from September 4th to 6th. This meeting gathers specialists in crystal growth, spectroscopy, nanostructures and devices for optics. We contributed with 2 oral and 3 poster presentations.


Associate editor

August 31, 2017

Philippe has joined the editorial board of Journal of Luminescence, a publication from Elsevier devoted 
to all phenomena related to the emission of light. It covers the dynamics of localized excited states, energy transport in ordered and disordered systems, radiative and non-radiative relaxation processes, vibronic interactions in electronic excited states, coherent processes in excited states,  hole burning, etc… The editor in chief is Marco Bettinelli, from the Università degli Studi di Verona, Verona, Italy.

International Conference on Luminescence 2017

August 31, 2017

Philippe presented a plenary lecture at the International Conference on Luminescence (ICL 2017) which took place in João Pessoa, Brazil, from August 27th to September 1st 2017. The talk entitled "Rare Earth Doped Nanostructures: Quantum Leaps for Optical Technologies'' gave an overview of the developments on rare earth based nanoscale systems for optical quantum technologies with a focus on the work at Chimie ParisTech.

Alban also presented a talk on crystals with broad inhomogeneous linewidths for high-resolution, high-bandwidth  spectral analysis entitled “Effect of controlled disorder by scandium substitution in Tm:YAG for large bandwidth spectral analysis" by Alban Ferrier, Simon Ilas, Philippe Goldner, Anne Louchet-Chauvet.

ICL is a series of conferences held every three years which started in 1966. It is the largest conference in the field of luminescence and gathered more than 400 researchers this year.

Brazilian-French chair

August 15, 2017

Philippe has been selected for a Brazilian-French Chair in the State of São Paulo. He will work in the laboratory of Prof. Rogéria R. Gonçalves for two months starting in August 2017 at the  University of São Paulo (USP) on the campus of Ribeirão Preto. Rogéria Gonçalves is heading a team specialised in the synthesis of  rare earth doped nanoparticles and thin films for photonics applications. 

Bozeman's visit

July 24, 2017

In the context of French-American ANR project : DYSCRIS, Sacha visited Rufus Cone's and Charles Thiel's group in Montana State University, Bozeman MT during one month. The aim of the visit was to continue the study about the effect of a controlled disorder in Er3+:Y2SiO5 in order to increase the signal processing bandwidth and spectral multiplexing capacity.

NanoQtech first Newsletter

May 26, 2017

The first newsletter describing the main achievements over the first year of the European project NanoQtech has just been published.

Newsletter-Issue 1

NanoQtech Summer School

May 01, 2017

As part of the European project NanOQtech we organized a mini summer school that was held at Chimie ParisTech on May 2-4. This was a good chance for younger researchers to get familiar with quantum technologies and naomaterials. It also included some practical lab training sessions. The height of the meeting was the public conference given by Klaus Molmer on quantum computing to a broad audience...

Laser game

April 11, 2017

On April the 12th we all had our laser safety training by shooting at each others!