5th Institute of Physics
 
 
 
 

μ-cell

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Abstract


Figure 1: Small cells in a piece of glass can be filled with Rubidium atoms and excited to Rydberg states. Due to the blockade mechanism induced by the strong interaction among Rydberg states it might be possible to entangle two neighboring cells as e.g. required for a C-NOT gate. (pdf) An important aspect of this approach is the utilization of standard technologies in the production process which allows for full integration of larger cell arrays. These cells can be equipped with field plates to shift Rydberg states via the Stark shift into resonance and to activate individual sites. To connect two distant cells it is possible to include waveguide structures or optical fibers in the design.

Motivation

Controlled quantum correlations are at the heart of emerging quantum technologies for communication, information processing and computation. Atomic physics offers ultracold single atoms or ions which are studied in that context very successfully. Mostly due to the requirement of ultralow temperatures the scaling to a large number of interconnected devices is difficult. Mesoscopic ensembles of atoms which can be well controlled in their geometry and which provide coherent long range interactions promise a significant simplification for quantum devices and networks. They do not need to operate in well defined motional quantum states and finite temperatures up to even above room temperature operation of the resulting quantum devices might be possible. In case of a successful demonstration of the basic units the upscaling to quantum networks with millions of nodes seems within reach.

In this context we plan to study Rydberg interacting mesoscopic ensembles at room temperatures and above. Rydberg atoms are atoms in highly excited states with large principal quantum numbers n, and long lifetimes.

Fundamental aspects of the use of the so-called Rydberg blockade in mesoscopic ensembles for quantum devices and networks are studied in an ultracold environment. Here we investigate how to transfer these ideas to scalable ensembles in thermal micro-vapor cells. As the range of interaction can be on the order of micrometers, standard techniques in lithography can be used to produce mesoscopic ensembles confined in glass cells.

We aim at the demonstration of scalable single photon sources based on micro-vapor cells. The chosen technological approach is holistic in the sense that quantum devices like single photon sources, quantum memories and quantum repeaters can be integrated and interconnected on one platform.

Rydberg spectroscopy in thermal vapors

The strong interaction among Rydberg states leads to a blockade mechanism which only allows for one excitation into a Rydberg state within the blockade volume. This effect has been shown e.g. by our Rydberg experiments with ultracold atoms (pdf).

The key idea is to confine thermal vapors of alkalis in spectroscopy cells smaller than the blockade radius, which is on the order of a few microns. By this only one Rydberg excitation is allowed within one cell, or several close by cells. This system opens the way to a large nonlinearity on the single photon level with many possible applications in quantum information technology and quantum optics.

Microwave interactions

The large polarizability of Rydberg atoms has been used by several groups to measure d.c. electric fields at the level of ≥100 μV cm−1 using field ionization with atomic beams and EIT with ultracold atomic gases. In contrast, MW electric field measurements can rely on resonant transitions and the associated large transition dipole moment between neighbouring Rydberg states. The sensitivity to MW electric fields can be resonantly enhanced for frequencies in the range of 1–500 GHz, as there are many resonant electric dipole transitions between Rydberg states in this frequency band.

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Research

Pulsed Rydberg excitation in a thermal gas - coherent Rydberg dynamics on the nanosecond timescale

In future applications it will be necessary to control the Rydberg states coherently as a function of time. An always present source of incoherence is the motion of the atoms which has to be "frozen" during the time of the experiment. Compared to the Rydberg experiments with ultracold atoms this implies that the excitation has to be carried out roughly a thousand times faster, ergo within nanoseconds. It requires a million times more laser power to maintain the coherent transfer into Rydberg states in such a short time. Therefore we have set up a pulsed laser system to produce high power pulses of ~ 4ns duration and several 100µJ pulse energy.

Figure 2: Freezing Rydberg atoms. In our Rydberg-BEC setup we benefit from the fact that the atoms actually do not move during the excitation into Rydberg states and are therefore "frozen" in space. This regime is also desirable for a coherent Rydberg excitation in thermal vapors and the excitation time has to be accordingly reduced to a few nano-seconds.


Figure 3: (a) The Rydberg state is addressed with a two-photon-transition via an intermediate state. The laser for the upper transition is pulsed. (b) Transmission signal of the 780 nm laser (upper half) and corresponding laser intensities (lower half) as a function of time. (c) Simplified schematic of the optical setup.

 

Figure 4: With intense laser pulses on the order of a few 100µJ it is possible to coherently drive the transition to Rydberg states. As a function of time, we observe Rabi-oscillations. (a) By increasing the pulse energy these oscillation accelerate as expected from theory with the expected scaling ~ (pulse energy)1/2. Corresponding simulations of the absorption signal (b) and the Rydberg occupation (c).

Microscopic vapor cells

We have developed a method to produce vacuum tight microscopic vapor cells made of quartz glass for various spectroscopic applications. With the OBOVAC method (Optical Bonding Of Vacuum Atom Cells) (pdf) it is possible to fill cells with dimensions in the micrometer range with alkali vapors. By heating cells filled with Rubidium to 250°C it is possible to achieve in 10μm thick sample optical densities well above ten.

Figure 5: By standard lithographic methods it is possible to etch arbitrary structures in quartz glass which are subsequently filled with gaseous alkali atoms. The glass body allows for good sealing of the vacuum and excellent optical access. The SEM picture shows a channel with a width of 10 microns and an etched depth of 1 micron.

 

Figure 6: With a confocal microscope it is possible to obtain a spatial resolution in the range of the blockade radius. The picture shows the fluorescence and absorption spectra of a trapezoidal channel as a function of the position of the laser focus.

Precision spectroscopy of confined Rydberg atoms - wall interactions


Figure 7: To probe the effect of the quartz walls on close-by Rydberg atoms, we developed a wedge shaped cell to vary continuously the distance of the glass walls to the atoms. The spectroscopy uses the coherent transparency feature of a three level system (EIT-spectroscopy) to gain insight into the mechanisms and timescales of decoherence effects.


Figure 8: Rydberg atoms next to a glass wall interact with charges on the walls, their image charge due to the finite reflectivity and excitations of the glass itself.

A crucial point for excitation of the vapor to high lying Rydberg states is the interaction to close by walls. The weakly bond electron in a Rydberg atom leads to large polarizability and makes them very sensitive to small electric fields. Especially ions and electrons are likely to stick to the dielectric surface and might produce large electric fields. This effect can be measured precisely with the help of the unique Stark pattern of Rydberg atoms in D-states and leads only to a few V/cm. Another contribution is given by the finite reflectivity of the glass walls, which leads to small interaction of the Rydberg atom with its image and can be neglected here. Excitations in the material itself are important in terms of surface polaritons, which couple resonantly to certain Rydberg states.

With a combination of AM- and FM- spectroscopy, we were able to identify and avoid these modes resulting in a narrowband excitation (<20MHz) of Rydberg states located within one micron distance to a quartz wall.

 
Figure 9: EIT spectroscopy on the 43S and the 32S state as a function of the gap size. For the 43S state we observe a strong interaction with the glass walls caused by resonant coupling of the Rydberg atoms to surface polaritons. By choosing the Rydberg state such that no overlap of atomic dipole transitions and polaritonic modes occurs, as in the case of the 32S state, we maintain the linewidth of bulk vapors all the way down to one micron.

Microwave sensing

Figure 10: a) The energy level diagram for the four-level system used for the experiments. The top part of the inset shows an example EIT feature associated with the three-level system without a MW electric field. The bottom part of the inset shows an example of the bright resonance that is produced within the EIT window when a MW electric field is present. b) The experimental set-up used for the experiments.

As EIT depends on quantum interference, it is exquisitely sensitive to phase disturbances, transitions out of the participating states and energy level shifts of the three-level system. The addition of a MW electric field that is resonant with a nearby Rydberg transition, a fourth level, for the scheme shown in Fig. 10a, breaks the symmetry of the EIT interference and can produce a spectrally sharp bright resonance within the EIT line shape. The strength of the effect depends on the coupling to the MW electric field, which is determined by the Rabi frequency of the transition, wich itself depends on the amplitude of the MW electric field and the transition dipole moment. In [8] we demonstrate MW electric field measurements of ~8 μV cm−1.

The MW electric field polarization can be determined from the probe laser transmission by recognizing that the 53D5/2(F=4, mF=±4) states can be coupled to, or uncoupled from, the 54P3/2 manifold depending on the probe and coupling laser polarization relative to that of the MW electric field. Some excitation pathways present in the system shown in Fig. 11a) that pass through the stretched 53D5/2 (F=4, mF=±4) states are restricted to the three levels of the EIT ladder system, 5S1/2-5P3/2-53D5/2. Other excitation pathways take the system through the nonstretched 53D5/2 states and can experience the full four-level system. The behavior of the entire 52-state system can be understood by considering a few cases of laser and MW electric field polarizations.

Figure 11: a) Level diagram showing all 52 possible states addressed by the experiment. The arrows indicate allowed excitations for the σ-polarized probe and coupling beams and π-polarized MWs. The 54P3/2 states are shown above the 53D5/2 states for simplicity. On the right, the corresponding effective four-level system is shown. b) Theoretical line shapes resulting from a three-level (black) and four-level (red) system.

 

Figure 12: Schematic view of the setup including the cell in the foreground and the test antenna in the background. The laser propagation direction (red), the polarization of the two laser beams (blue), and an arbitrary polarization direction of the MW (magenta) are shown together with the relevant angles between them as described in the main text. The shadows are the projections onto the x-y plane on the left and the x-z plane in the back.

 

  • The case where the probe and coupling lasers are linearly polarized along the same direction as the MWs is shown in Fig. 11b (black). In this case,  transitions are driven throughout the system and all the excitation pathways experience a four-level system. The probe laser is absorbed on resonance.
  • Also displayed in Fig. 11b (red) is the case where the probe and coupling lasers are σ-polarized and excite ΔmF=+1 transitions. The atoms are optically pumped such that the stretched states of the 5S1/2, 5P3/2, and 54D5/2 manifolds dominate. The MW electric field is polarized in the z-direction. In this case, the three-level excitation pathways are overwhelmingly favored since a  MW transition cannot couple the stretched states to the 54P3/2 manifold.
  • If the probe and coupling lasers are both linearly polarized parallel to each other, e.g., y-polarized, but orthogonal to the MW electric field polarization, e.g., z-polarized, there are both three-level and four-level excitation pathways open. This behavior derives from the fact that in a z-atomic basis the MW electric field drives π transitions, while the y-polarized probe and coupling lasers drive transitions throughout the 53D5/2 manifold, as they are in a superposition of σ+ and σ- polarizations in the z-basis.

 

Any MW electric field can be split into a component that couples atoms to the 54P3/2 state and one that does not. The relative strength of the components only depends on the MW electric field polarization relative to the polarization and propagation direction of the two laser beams. When rotating parallel linear probe and coupling laser polarizations around their propagation axes, the projection of the MW electric field on the probe and coupling laser polarization changes. The change of the MW electric field polarization projection relative to the laser polarizations results in a variation of the probe laser transmission. The probe laser transmission changes can be used to determine the MW electric field polarization since the probe and coupling laser polarizations are known. We demonstrated this in [12].

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Outlook

The blockade mechanism, which allows for only one excitation within the blockade radius represents an optically nonlinearity on the single photon level which may be exploited in various schemes. (pdf)

Single Photon source

Figure 13: An obvious application is a single photon source in which the singly excited state is converted into a photon. By exploiting a four wave mixing scheme it is possible to do this deterministically and one is not dependent on a spontaneous decay. In addition to this, the emission pattern of the single photons can be highly directional because the emitter consists of an ensemble of thermal atoms with extensions much larger than the optcial wavelengths involved.

Integrated devices

Figure 15: The fabrication of microscopic vapor cells uses standard methods of glass machining (pdf) and is therefore highly integrable and also scalable. Different functional units can be combined by waveguides to establish complex quantum networks.

 

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Highlights

 08.12.2016Charge-induced optical bistability in thermal Rydberg vapor more...
15.06.2015Atomic vapor spectroscopy in integrated photonic structures more...
 05.02.2015Strongly correlated growth of Rydberg aggregates in a vapor cell more...
07.07.2014Eine Photonen-Drehtür bei Raumtemperatur more...
05.03.2014Anodic bonding of optogalvanic spectroscopy cells with electrical feedtroughs more...
 06.02.2013Evidence for strong van der Waals-type Rydberg-Rydberg interaction in thermal vapor more...
13.07.2012Fabrication and characterization of an electrically contacted vapor cell more...
 04.07.2012Four-wave mixing involving Rydberg states in a thermal vapor of Rb more...
 12.10.2011GHz Rabi flopping to Rydberg states in hot atomic vapor cells more...
13.01.2010Giant Rydberg atoms confined in a micro-glasscell more...

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

The Crew

Ralf Albrecht(Master Student)
Marija Curcic(Gast (University of Belgrade))
Georg Epple(Doktorand (Kooperation MPL Erlangen))
Markus Fiedler(Master Student)
Kateryna Guguieva(HiWi)
Richard Hermann(Bachelor Student)
Patrick Kaspar(Master Student)
Harald Kübler(Gruppenleiter)
Maximilian Kühn(HiWi)
Maxim Leyzner(Bachelor Student)
Robert Löw(Group leader)
Tilman Pfau(Institutsleiter)
Christoph Pitzal(Bachelor Student)
Marius Plach(Bachelor Student)
Fabian Ripka(Doktorand)
Ralf Ritter(Doktorand)
Johannes Schmidt(Doktorand)
Nico Sieber(Master Student)
Artur Skljarow(Master Student)
Daniel Weller(Doktorand)
Arzu Yilmaz(Gast (Tuebingen))

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Refs & Publications

[1]H. Kübler, J. P. Shaffer, T. Baluktsian, R. Löw, and T. Pfau
"Coherent excitation of Rydberg atoms in micrometre-sized atomic vapour cells"
Nature Photonics 4, 112 (2010); doi: 10.1038/nphoton.2009.260
[2]T. Baluktsian, C. Urban, T. Bublat, H. Giessen, R. Löw, and T. Pfau
"Fabrication method for microscopic vapor cells for alkali atoms"
Opt. Lett. 35, 1950 (2010); doi: 10.1364/OL.35.001950
[3]D. Barredo, H. Kübler, J.P. Shaffer, T. Baluktsian, H. Giessen, R. Löw and T. Pfau
"Observation of Electromegnatically Induced Transparency involving Rydberg States in Microcells"
proceedings of the XX International Conference "Laser Spectroscopy" (ICOLS 2011)
[4]J. Honer, R. Löw, H. Weimer, T. Pfau, and H. P. Büchler
"Artificial atoms can do more than atoms: Deterministic single photon subtraction from arbitrary light fields"
Phys. Rev. Lett. 107, 093601 (2011); doi: 10.1103/PhysRevLett.107.093601
[5]B. Huber, T. Baluktsian, M. Schlagmüller, A. Kölle, H. Kübler, R. Löw, T. Pfau
"GHz Rabi flopping to Rydberg states in hot atomic vapor cells"
Phys. Rev. Lett. 107, 243001 (2011); doi: 10.1103/PhysRevLett.107.243001
[6]R. Daschner, R. Ritter, H. Kübler, N. Frühauf, E. Kurz, R. Löw, T. Pfau
"Fabrication and characterization of an electrically contacted vapor cell"
Opt. Lett. 37, 2271 (2012); arXiv:1204.2391; doi: 10.1364/OL.37.002271
[7]A. Kölle, G. Epple, H. Kübler, R. Löw, and T. Pfau
"Four-wave mixing involving Rydberg states in a thermal vapor cell"
Phys. Rev A 85, 063821 (2012); doi: 10.1103/PhysRevA.85.063821
[8]J. Sedlacek, A. Schwettmann, H. Kübler, R. Löw, T. Pfau, J.P. Shaffer
"Quantum Assisted Electrometry using Bright Atomic Resonances"
Nature Physics 8, 819–824 (2012); doi: 10.1038/nphys2423
[9]M. M. Müller, A. Kölle, R. Löw, T. Pfau, T. Calarco, and S. Montangero
"Room temperature Rydberg Single Photon Source"
Phys. Rev. A 87, 053412 (2013); arXiv:1212.2811v1; doi: 10.1103/PhysRevA.87.053412
[10]T. Baluktsian, B. Huber, R. Löw, T. Pfau
"Evidence for strong van der Waals-type Rydberg-Rydberg interaction in thermal vapor"
Phys. Rev. Lett. 110, 123001 (2013) ; editor’s choice; doi: 10.1103/PhysRevLett.110.123001
[11]D. Barredo, H. Kübler, R. Daschner, R. Löw, T. Pfau
"Electrical read out for coherent phenomena involving Rydberg atoms in thermal vapor cells"
Phys. Rev. Lett. 110, 123002 (2013); arXiv:1209.6550; doi: 10.1103/PhysRevLett.110.123002
[12]J. A. Sedlacek, A. Schwettmann, H. Kübler and J. P. Shaffer
"Atom-Based Vector Microwave Electrometry Using Rubidium Rydberg Atoms in a Vapor Cell"
Phys. Rev. Lett. 111, 063001 (2013); doi: 10.1103/PhysRevLett.111.063001
[13]A. Urvoy, C. Carr, R. Ritter, C. S. Adams, K. J. Weatherill, and R. Löw
"Optical coherences and wavelength mismatch in ladder systems"
J. Phys. B: At. Mol. Opt. Phys. 46 245001 (2013); doi: 10.1088/0953-4075/46/24/245001
[14]G. Epple, K. S. Kleinbach, T. G. Euser, N. Y. Joly, T. Pfau, P. St.J. Russell, R. Löw
"Rydberg atoms in hollow-core photonic crystal fibres"
Nature Communications5, 4132; doi: 10.1038/ncomms5132
[15]H. Q. Fan, S. Kumar, R. Daschner, H. Kübler and J. P. Shaffer
"Subwavelength microwave electric-field imaging using Rydberg atoms inside atomic vapor cells"
Opt. Lett. 39, 3030-3033 (2014); doi: 10.1364/OL.39.003030
[16]R. Daschner, H. Kübler, R. Löw, H. Baur, N. Frühauf, T. Pfau
"Triple stack glass-to-glass anodic bonding for optogalvanic spectroscopy cells with electrical feedthroughs"
Appl. Phys. Lett. 105, 041107; arXiv:1403.1093; doi: 10.1063/1.4891534
[17]S. M. Ulrich, S. Weiler, M. Oster1, M. Jetter, A. Urvoy, R. Löw, and P. Michler
"Spectroscopy of the D1 transition of cesium by dressed-state resonance fluorescence from a single (In,Ga)As/GaAs quantum dot"
Phys. Rev. B 90, 125310
[18]Wilhelm Kiefer, Robert Löw, Jörg Wrachtrup & Ilja Gerhardt
"Na-Faraday rotation filtering: The optimal point"
10.1038/srep06552; doi: 10.1038/srep06552
[19]B. Huber, A. Kölle and T. Pfau
"Motion-induced signal revival in pulsed Rydberg four-wave mixing beyond the frozen-gas limit"
Phys. Rev. A 90, 053806; editor’s choice; arXiv:1410.0897; doi: 10.1103/PhysRevA.90.053806
[20]A. Urvoy, F. Ripka, I. Lesanovsky, D. Booth, J. P. Shaffer, T. Pfau and R. Löw
"Strongly Correlated Growth of Rydberg Aggregates in a Vapor Cell"
Phys. Rev. Lett. 114, 203002 (2015); editor’s choice; arXiv:1408.0039; doi: 10.1103/PhysRevLett.114.203002
[21]R. Ritter, N. Gruhler, W. Pernice, H. Kübler, T. Pfau, R. Löw
"Atomic vapor spectroscopy in integrated photonic structures"
Appl. Phys. Lett. 107, 041101 (2015); arXiv:1505.00611; doi: 10.1063/1.4927172
[22]H. Fan, S. Kumar, J. Sedlacek, H. Kübler, S. Karimkashi and J. P. Shaffer
"Atom based RF electric field sensing"
Journal of Physics B: Atomic, Molecular and Optical Physics 48, 202001; doi: 10.1088/0953-4075/48/20/202001
[23]Y. Chen, F. Ripka, R. Löw, T. Pfau
"Pulsed Rydberg four-wave mixing with motion-induced dephasing in a thermal vapor"
Appl. Phys. B 122:18, 1-6 (2016); arXiv:1512.04843; doi: 10.1007/s00340-015-6277-8
[24]H. Q. Fan, S. Kumar, H. Kübler and J. P. Shaffer
"Dispersive radio frequency electrometry using Rydberg atoms in a prism-shaped atomic vapor cell"
Journal of Physics B: Atomic, Molecular and Optical Physics 49, 104004; doi: 10.1088/0953-4075/49/10/104004
[25]C. Veit, G. Epple, H. Kübler, T. G. Euser, P. St. J. Russell and R. Löw
"RF-dressed Rydberg atoms in hollow-core fibres"
Journal of Physics B: Atomic, Molecular and Optical Physics 49, 134005; doi: 10.1088/0953-4075/49/13/134005
[26]R. Ritter, N. Gruhler, W. H. P. Pernice, H. Kübler, T. Pfau and R. Löw
"Coupling thermal atomic vapor to an integrated ring resonator"
New Journal of Physics 18, 103031 (2016); doi: 10.1088/1367-2630/18/10/103031
[27]D. Weller, A. Urvoy, A. Rico, R. Löw and H. Kübler
"Charge-induced optical bistability in thermal Rydberg vapor"
Phys. Rev. A 94, 063820; doi: 10.1103/PhysRevA.94.063820
[28]D. Weller, A. Yilmaz, H. Kübler and R. Löw
"High vacuum compatible fiber feedthrough for hot alkali vapor cells"
Appl. Opt. 56, 1546-1549; doi: 10.1364/AO.56.001546

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Open Positions

Integrated atomic spectroscopy with photonic waveguides

Joint Ph.D. position: The Hebrew University of Jerusalem and the University of Stuttgart

Cavity QED is a basis for quantum information processing and devices. In order to transform these ideas into practical room temperature devices we investigate atomic vapor cells in combiantion with integrated light fields. The goal of this thesis is to study the coupling of thermal vapours to the evanescent field of photonic waveguides and resonators. We want to study the coupling of room temperature Rubidium atoms to nanoscopic resonators towards the strong coupling regime. The prospective student will develop new types of photonic structures in Jerusalem and perform the measurements on the atom-light coupling in Stuttgart.

By working in Jersualem and Stuttgart the PhD student will acquire expertise in atomic spectroscopy, nano-photonics and nano-structuring.

  • R. Ritter, N. Gruhler, W. Pernice, H. Kübler, T. Pfau and R. Löw,
    "Atomic vapor spectroscopy in integrated photonic structures”
    Appl. Phys. Lett. 107, 041101 (2015)
  • L. Stern, B. Desiatov, I. Goykhman and U. Levy,
    “Nanoscale light–matter interactions in atomic cladding waveguides”,
    Nature Communications 4 1548 (2013)
     

Contacts:

mailto icon U. Levy (Jerusalem), mailto icon R. Löw (Stuttgart)

Hot Rydberg atoms inside hollow core fibres

Joint Ph.D. position: The Max-Planck Institute for the Science of Light (Erlangen) and the University of Stuttgart

The goal of this thesis is to study optical non-linearities of strongly interacting Rydberg atoms inside hollow-core photonic crystal fibres. Especially the sensitivity of Rydberg atoms to microwave and THz radiation makes this a promising system for sensing applications. The prospective student will develop new types of hollow core fibres adapted to the properties of Rydberg atoms in Erlangen. The spectroscopy of Rydberg atoms inside these fibres will be carried out in Stuttgart.

By working in Erlangen and in Stuttgart the PhD student will acquire expertise in the field of photonic crystal fibres, in atomic spectroscopy and Rydberg physics. The concept of a joint PhD student Erlangen/Stuttgart has already been implemented successfully.

  • G. Epple, K. S. Kleinbach, T. G. Euser, N. Y. Joly, T. Pfau, P. St. J. Russell and R. Löw,
    "Rydberg atoms in hollow-core photonic crystal fibres",
    Nature Communications 5, 4132 (2014)

Contacts:

mailto icon N. Joly (Erlangen), mailto icon R. Löw (Stuttgart), Flyer

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Bachelor- and Master-Topics

Laser amplifier @474nm (Bachelor Thesis)

Kagome fiber

This project aims at setting up a laser amplifier at 474nm. Based on an existing setup, the amplification will be improved and the spectral properties of the output light will be analized. Finally the light will be used to do Rydberg spectroscopy in a thermal vapor cell.

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Alkali Spectroscopy in Buffer Gases (Bachelor Thesis)

The project will investigate broadening mechanisms due to buffer gases. We will investigate dipolar- and non-dipolar buffer gases and their effect on ground_state and Rydberg states in thermal gases.

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Fabry-Pérot  Reference for Cs excitation (Bachelor Thesis)

In this project a Fary-Pérot interferometer (FPI) will be constructed and referenced to an existing 895nm laser, which itself is referenced to an atomic spectroscopy setup. Once the FPI is stabilized, a 1070nm laser will be referenced to the FPI. The frequency stability of the 1070nm laser will be investigated and will be used for Rydberg excitations in themal Cs vapor.

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Laser package @474nm (Bachelor Thesis) (assigned)

This project is a collaboration with the IHFG. We plan to develop a blue laser source in a compact package based on the VECSEL-technology developed at the IHFG. This light source will be integrated in our trace gas sensor project.

The new laser source will be compared to an existing commercial laser source at the PI5.

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

FM Spectroscopy in hollow core fibers (Bachelor Thesis) (assigned)

Kagome fiber

In this project we will study Rydberg atoms inside photonic crystal fibers to study optical nonlinearities. Especially designed fibers for the multi photon excitation scheme allow for optimal overlap between light and atoms. One of the main goals is to observe the coupling between two hollow-core fibers by microwave photon exchange.

The Bachelor Project will focus on frequency modulation spectroscopy of thermal Rydberg atoms inside these fibers.

Relevant publications:

  1. G. Epple, K. S. Kleinbach, T. G. Euser, N. Y. Joly, T. Pfau, P. St.J. Russell, R. Löw

    "Rydberg atoms in hollow-core photonic crystal fibres"
    Nature Communications 5, 4132; doi: 10.1038/ncomms5132

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Energy Pooling in thermal Rb vapor cells (Bachelor Thesis) (assigned)

Ofen for Sigle Photon Generation Cell

One limiting factor in our single photon generation experment is background light originating from the Rubidium vapor. In this project we will investigate energy pooling in this system as one of the possible sources for the background light.

Relevant publications:

  1. L. Barbier and M. Cheret

    "Energy pooling process in Rubidium vapor"
    Journal of Physics B: Atomic and Molecular Physics 16, 3213

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Charge Based Bistability in Three Photon Excitation Schemes (Bachelor Thesis) (assigned)

The project will clarify the underlying mechanism for an optical bistability observed with a three photon excitation scheme in cesium. For a two photon scheme and rubidium, clear evidence has been found that charges are responsible for the observed phenomenon [1], yet open questions remain. To substantiate our interpretation of the bistability, we again combine two independent EIT-schemes, for cesium by overlapping a total of 5 lasers in a thermal vapor cell. We expect to extend our theory also to the conditions used in the original publication [2], where the bistability has been observed for the first time.

Relevant publications:

  1.  D. Weller, A. Urvoy, A. Rico, R. Löw, H. Kübler
    "Charge-induced optical bistability in thermal Rydberg vapor"
    Physical Review A 94, 063820
  2. C. Carr, R. Ritter, C. G. Wade, C. S. Adams, and K. J. Weatherill
    "Nonequilibrium Phase Transition in a Dilute Rydberg Ensemble"
    Physical Review Letters 111, 113901

     

Contacts:

mailto icon H. Kübler , mailto icon R.Löw

 

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding

Funding


ERC-Logo

The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. [xxxxxx]

Abstract | Research | Outlook | Highlights | The Crew | Refs & Publications | Open Positions | Bachelor- and Master-Topics | Funding