Spontaneous emission of radiation is the process that governs how matter scatter light making objects visible. Visibility is at the core of our senses and its control is amenable for microscopy, optomechanics and quantum information. In many quantum applications, it is accepted that the natural process of spontanoues emission sets the ultimate limits for measurements and operations because the emission is viewed as an inevitable form of dechorence emerging from the coupling of the quantum system with the enviroment. We want to change this perspective and, in the research line we follow, we tackle the problem of suppressing and controlling spontaneous emission to an extend relevant for future quantum applications.


Our reserach area/projects

  • Invisibility of an atomic ion
  • Quantum information with 13xBa
  • Optomechanics with dipolar scatterers
  • Antimatter at low energy


Invisibility of an atomic ion

We want to control the spotanoues emission of a levitated atom with a hemispherical mirror. The mirror is used to reflect part of the emitted radiation back onto the emitters to interfere with the on-going process of emission. This design can achieve much larger suppression of SE than a cavity QED system thanks to the possibility to control the emitted light from all the directions of space. With our mirror [1], we plan to suppress the emission rate by 96% entering in a new regime where applications are possible. This result will enalble us to extend the lifetime of optical clocks, engineer qubits on dipole transitions, change the way atoms decay when excited and a lot more [2]

Mounted optics and trap render

In addition to a higher light collection efficiency, this new design will allow us to study phenomena such the strong inhibition of the spontaneous decay, and the enhancement of the emission rate of the ion [2].



[1] D. Higginbottom, G. Campbell, G. Araneda, F. Fang, Y. Colombe, B. C. Buchler, P. K. Lam, Sci. Rep. 8, 221 (2018)

[2] G. Araneda, G. Cerchiari, D. B. Higginbottom, P. C. Holz, K. Lakhmanskiy, P. Obšil, Y. Colombe, and R. Blatt, Rev. Sci. Instrum. 91, 113201 (2020)


Quantum information with 13xBa

Trapped ions are among the most promising candidates for the near-future realization of quantum computers. In this computers, the unit of quantum information (qubits) are encoded into the electronic quantum states of trapped ions. To perform a computation, the information encoded in the qubits is elaborated and exchanged via quantum operations that are realized by carefully illuminating the ions with precise laser pulses. Altough many atomic ions can be used as qubits, we think that ions such as 133Ba or 137Ba will offer a decisive advantage to perform the quantum operation with outstanding fidelities allowing to extend the complexity of the quantum calculations beyond the design of current architectures.


Optomechanics with levitated dipolar scatterers


self homodyne webpage


  The study of levitated dipolar scatterers is a growing field in physics that promises to uncover the connection between quantum mechanics and gravity, to access the QED forces exert on atoms by external boundary conditions and to deliver future devices for ultra-precise force sensing. In collaboration with the nanosphere team of the QI group, we investigate how the measure the position of these scatterers by controlling their spontaneous emission (SE) with a spherical mirror. Developing on the experience of atomic experiments [3, 4], we applied our method to a silica nanoparticle [1, 2]. This technique, unlike other state-of-the-art techniques, can reach the Heisenberg limit of detection, i.e. when the position measurement is only bounded by the recoil force of the scattered light.
  The setup splits the solid angle surrounding the scatterer into two regions as depicted in the figure. Half of the solid angle is occupied by a mirror and half by a detector. The mirror produces an image of the dipolar scatterer that interferes with the primary emitted field at the detector. This configuration realizes the self-homodyne of the emitted field by self-interfering each emitted photon. Self-interference allows controlling the SE of the scatterer while obtaining superior mode-matching of the radiation fields for homodyne detection. The radiation exists from the scatterer-mirror system only from one side enabling the measurement with only a single one-sided detector.
  The new method is suitable for precision studies of any dipolar scatterer such as atoms and nanoparticles without requiring the existence of a complex electronic structure.The self homodyne configuration for detection can also be extended to sense the motion of an ion chain as depicted in the following figure ions [3].

two ion detection




[1] "Position Measurement of a Levitated Nanoparticle via Interference with Its Mirror Image", L. Dania, K. Heidegger, D. S. Bykov, G. Cerchiari, G. Araneda, T. E. Northup, Phys. Rev. Lett. 129, 013601 (2022) 

[2] "Position measurement of a dipolar scatterer via self-homodyne detection", G. Cerchiari, L. Dania, D. S. Bykov, R. Blatt, and T. E. Northup, Phys. Rev. A 104, 053523 (2021) 

[3] "Measuring Ion Oscillations at the Quantum Level with Fluorescence Light", G. Cerchiari, G. Araneda, L. Podhora, L. Slodička, Y. Colombe, and R. Blatt, Phys. Rev. Lett. 127, 063603 (2021)

[4] "Motion analysis of a trapped ion chain by single photon self-interference" G. Cerchiari, G. Araneda, L. Podhora, L. Slodička, Y. Colombe, and R. Blatt, Appl. Phys. Lett. 119, 024003 (2021)


CARONTE - Compact AntipROtoN Transfer dEvice

CaronteLogo small

Researchers who are interested in studying and developing future technologies based on Antimatter are currently limited by the availability of antiprotons, which can only be accessed at CERN in Geneva. This limitation greatly discourage the development in this field because of the added costs in terms of resources and time that emerge from having to develop innovation physically at CERN. To solve this problem, we are developping a prototype to trasport antiprotons from the CERN’s facilities to any other institution.

project supported by: 1669 Prototypenentwicklung des Förderkreises 1669


Project members

Gio 02 800 800 1
Dr. Giovanni Cerchiari (University Assistant - PostDoc)

e-mail: giovanni.cerchiari(at)

room: 4/06


WEISER Yannick web

Yannick Weiser (Ph.D. student)

e-mail: yannick.weiser(at)

room: 4/06

PANZL Lorenz web 400 300

Lorenz Panzl (Ph.D. student)

e-mail: lorenz.panzl(at)

room: 4/06



Tommaso Faorlin (Ph.D. student)

e-mail: tommaso.faorlin(at)

room: 4/06



 Thomas Lafenthaler(Master student)

e-mail: thomas.lafenthaler(at)



Prof. Rainer Blatt (senior advisor)

 Barium 2023 04

Picture of the Barium team (05/2023)

From left to right: Y. Weiser, S. Alfaro, G. Cerchiari, L. Panzl, T. Lafenthaler, T. Faorlin


Former members

Yves Colombe (now at Infineon Technologies, AT)

Gabriel Araneda (now at the University of Oxford, UK)

Lukáš Podhora (visiting PhD student from the Palacký University)

Daniel Higginbottom (PhD student, also with the ANU in Canberra, Australia)

Petr Obšil (visiting PhD student from the Palacký University)

Nicolas Chauvet (master student, ENS Lyon, France)

Lukáš Slodička (now at the Palacký University in Olomouc, Czech Republic)

Gabriel Hétet (now at the Laboratoire Pierre Aigrain, École Normale Supérieure, France)

Nadia Röck (now at the Univ. Klinik für Strahlentherapie-Radioonkologie, Innsbruck)

Sebastian Gerber (now at CERN on the AEgIS experiment)

Daniel Rotter (now at Swarovski Optik)







  • Gabriel Araneda
    Experiments with single photons emitted by single atoms
    Ph.D. thesis, 2020. Download
  • Daniel Higginbottom
    Atom-light couplers with one, two and ten billion atoms
    Ph.D. thesis, 2018, Australian National University. Download

  • Lukáš Slodička
    Single ion - single photon interactions in free space
    Ph.D. thesis, 2013. Download

  • Nadia Röck
    Quantum manipulation on the Barium quadrupolar transition
    Master's thesis, 2011. Download

  • Sebastian Gerber
    Quantum correlation experiments with resonance fluorescence photons of single Barium ions
    Ph.D. thesis, 2010. Download

  • Daniel Rotter
    Quantum feedback and quantum correlation measurements with a single Barium ion
    Ph.D. thesis, 2008. Download

  • Pavel Bushev
    Interference experiments with a single barium ion: from QED towards quantum feedback
    Ph.D. thesis, 2004. Download

  • Christoph Raab
    Interference experiments with the fluorescence light of Ba+ ions
    Ph.D. thesis, 2001. Download