past events

Thursday 22. February 2018

LECTURE ANNOUNCEMENT
Subradiance and Selective Radiance in Atomic Arrays

 

Organisation: Max Planck Institute for the Science of Light / Genes Research Group

Speaker: Mariona Moreno-Cardoner, ICFO (Institute of Photonic Science), Barcelona, Spain

Place: MPL / seminar room 1.500

Abstract:

Achieving controlled coherent interactions between photons and atomic media is a central goal in quantum optics, and essential for many applications in quantum information processing and quantum metrology. Spontaneous emission, in which photons are absorbed by atoms and then re-scattered into undesired channels poses a fundamental limitation in all these tasks. In typical theoretical treatments of atomic ensembles, it is assumed that this re-scattering occurs independently, and at a rate given by a single isolated atom, which in turn gives rise to standard limits of fidelity in applications such as quantum memories for light or photonic quantum gates. However, this assumption can be in fact dramatically violated. In particular, it has long been known that spontaneous emission of a collective atomic excitation can be significantly enhanced or suppressed through strong interference in emission between atoms — the physics of super- and sub-radiance. While these concepts are not new, the physics underlying these effects have not been completely understood. 

In this talk we will first discuss a theoretical framework that captures multiple scattering and interference of light while propagating through the atoms [1]. Using this formalism, we will then show how sub-radiant states in a periodic atomic chain acquire an elegant interpretation in terms of optical modes that are “guided” by the array, which only emit due to scattering from the boundaries of the finite system. Then, we will introduce the new concept of selective radiance. Whereas sub-radiant states experience a reduced coupling to all optical modes, selectively radiant states are tailored to simultaneously radiate efficiently into a desired channel and to suppress emission into undesired directions, thus enhancing the atom-light interface. We will show that these states naturally appear in chains of atoms coupled to nanophotonic structures. As a relevant application of how they can be exploited, we will show that selectively radiant states allow for a photon storage error that performs exponentially better with number of atoms than previously known bounds.

[1] A. Asenjo-Garcia, J. D. Hood, D. E. Chang, H. J. Kimble, Phys. Rev. A 95, 033818 (2017).

[2] A. Asenjo-Garcia, M. Moreno-Cardoner, A. Albrecht, H. J. Kimble, D. E. Chang, Phys. Rev. X 7, 031024 (2017).

Thursday 22. February 2018

IMPRS monthly meeting
Tour at INTEGO

 

Organisation: Marc Pleinert (FAU/ Institute of Optics, Information and Photonics)

What: Tour at INTEGO (develops and produces camera inspection systems)

Where: Henri-Dunant-Str. 8, 91058 Erlangen

What else: Please register for the tour by filling out the doodle (link has been sent by e-mail) until February 14th!

Thursday 15. February 2018

LECTURE ANNOUNCEMENT
Firmengründungen durch Inkubation im Bereich der Photonik - erste Ergebnisse und Erfahrungen

 

Organisation: Max Planck Institute for the Science of Light / Leuchs Division

Speaker: Prof. Dr. G. Marowsky (Laser Laboratorium Göttingen

Place: MPL / room A.2.500

Wednesday 31. January 2018

IMPRS monthly meeting

 

Organisation: Cameron Okoth (MPL/ Chekhova Research Group)

Talk: Non-classical light in high-precision interferometry

Speaker: Farid Khalili (Lomonosov Moscow State University)

Place: MPL / room A.2.500

Abstract:

Quantum mechanics applies a hierarchy of limitations on the precision of optical interferometric measurements. The most well-known one is the Shot Noise Limit which originates from the phase fluctuation of the probing light. If the optical power is high enough then perturbation of the mirrors mechanical motion imposed by the light power fluctuations also becomes important, leading to the Standard Quantum Limit (SQL). Methods for suppressing or avoiding of these fluctuations based on non-classical states of light are under active development now. The simplest of them, namely the injection of squeezed light into the interferometer, is already used in the gravitational-waves detector GEO600. More sophisticated methods, like frequency-dependent squeezing or intracavity parametric amplification of light, are planned for use in future gravitational-waves detectors.

Wednesday 31. January 2018

LECTURE ANNOUNCEMENT
Variational Study of Fermionic and Bosonic Systems with Non-Gaussian States: Theory and Applications

 

Organisation: Max Planck Institute for the Science of Light / Marquardt Division

Speaker: Dr. Tao Shi (Institute of Theoretical Physics  (Beijing, China) and Max Planck Institute of Quantum Optics (Garching))

Place: MPL / room A.1.500

Abstract:

We present a new variational method for investigating the ground state and out of equilibrium dynamics of quantum many-body bosonic and fermionic systems. Our approach is based on constructing variational wavefunctions which extend Gaussian states by including generalized canonical transformations between the fields. The key advantage of such states compared to simple Gaussian states is presence of non-factorizable correlations and the possibility of describing states with strong entanglement between particles. In contrast to the commonly used canonical transformations, such as the polaron or Lang-Firsov transformations, we allow parameters of the transformations to be time dependent, which extends their regions of applicability. Our formalism allows us not only to determine the energy spectrum of quasiparticles and their lifetime, but to obtain the complete spectral functions and to explore far out of equilibrium dynamics such as coherent evolution following a quantum quench. We illustrate and benchmark this framework with the non-equilibrium dynamics in the spin-boson and Kondo models.

Tuesday 30. January 2018

LECTURE ANNOUNCEMENT
Wigner Functions for the Canonical Pair Angle and Orbital Angular Momentum with Applications to Quantum Information

 

Organisation: Max Planck Institute for the Science of Light / Leuchs Division

Speaker: Prof. Dr. Hans Kastrup (DESY, Hamburg)

Place: MPL / room A.2.500

Abstract:

The concept of Wigner functions on classical phase spaces of physical systems, with the aim to describe the corresponding quantum mechanical statistical properties of those systems, is well-established for planar phase spaces. It is shown how that concept can be generalized to cylindrical ones {(q,p) in S^1 x R} like angle theta and orbital angular momentum p of a classical rotator.  Crucial new ingredients are the replacement of the angle theta by the equivalent pair (cos q, sin q) and the interpolation of the discontinuous quantum mechanical angular momenta m = 0, +1, -1,... in terms of the continuous classical momentum p by means of Whittaker's "cardinal" function, well known from interpolation and signal processing theories. Otherwise many structural properties of planar and cylindrical Wigner functions are very similar. The new framework is applied to elementary concepts of quantum information: qubits, cat states, 2-qubits like entangled EPR/Bell states.
The results may be useful for the description and analysis of quantum information experiments with orbital angular momenta of (Laguerre-Gauss) light beams or electron beams.

Monday 29. January 2018

LECTURE ANNOUNCEMENT
GINGERINO and the GINGER Project

 

Organisation: Max Planck Institute for the Science of Light / Leuchs Division

Speaker: Angela Di Virgilio (Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Pisa, Pisa, Italy)

Place: MPL / room A.2.500

Abstract:

GINGER (Gyroscopes IN General Relativity) is a proposal aiming at measuring the LenseThirring effect with an experiment based on Earth. It is an array of ring lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth.
Rotation and angular measurements are of great importance for various fields of science: General Relativity predicts rotation terms originated from the kinetic term, Earth Science studies the Earth's angular velocity and all ist variations, the tides and related perturbations, the normal modes of the Earth, the angular perturbations associated to the movement of the plates, the deformations of hydrological nature, without neglecting the rotational signals produced by the earthquakes. A ring laser integral to the Earth's surface is sensitive not only to the angular rotation of the planet, but also to all the global and local rotational signals to which it is subjected. For this reason GINGER is relevant for geophysics.
GINGERINO is a ring laser prototype installed inside the underground laboratory of the Gran Sasso, it has been built in order to validate the laboratory for GINGER. Its 
typical sensitivity is below 0.1 nrad/s in 1 second measurement. GINGERINO has validated LNGS for GINGER and it is now used for geophysical measurements. It is taking data since May 3 2017, typical data will be shown.

Thursday 25. January 2018

LECTURE ANNOUNCEMENT
Imaging neuronal activity in the freely moving animal: from the eye to the cortex

 

Organisation: Max Planck Institute for the Science of Light / Russell Division

Speaker: Dr Jason Kerr, Center of Advanced European Studies And Research (caesar), an Institute of the Max-Planck Society, Bonn

Place: MPL / room A.1.500

Abstract:

Motivation underlies the performance of self-determined behavior and is fundamental to decision making, especially with regard to seeking food, mates, and avoiding peril. As many decision making based behaviors in rodents involve a combination of head movements, eye movements, vestibular driven neuronal activity and active sensing of the environment to guide the behavior, studying the freely moving animal is paramount.

To achieve this, what is necessary is the precise tracking of the animal’s movement and interaction with the environment. Here I will outline work from our group that focuses on how freely moving rodents use their vision during decision making tasks and resulting cortical activity.

I will introduce methods that allow accurate recording of neuronal activity from populations of cortical neurons, using multiphoton imaging techniques, while simultaneously tracking eye and head movements during decision making in the freely moving rodent.

The second half of the presentation will focus on recent results from our lab showing how freely moving rodents have a distinct eye movement strategy that is of major evolutionary benefit.

Wednesday 24. January 2018

LECTURE ANNOUNCEMENT
New Spectroscopic Methods in Quantum Photonics: Accessing Multiphoton Processes and Correlated Noise

 

Organisation: Max Planck Institute for the Science of Light / Sandoghdar Division

Speaker: Dr. Tomás Ramos, Spanish Research Council (CSIC), Madrid, Spain

Place: MPL / room A.1.500

Abstract:

We present new methods for characterizing multiphoton scattering processes and correlated dephasing noise in experiments with propagating photons. First, we provide a spectroscopic protocol to characterize the photon-photon interactions mediated by any photonic quantum device such as a single molecule in free space or in a waveguide [1]. The protocol relies on coherent state inputs and homodyne detection at the output and provides simultaneous information about multiple --elastic and inelastic-- segments of the scattering matrix. Finally, we show how correlated dephasing noise is manifested in the line shapes of quantum emitters and how the same information contained in standard time-resolved Ramsey experiments can be extracted spectroscopically.

[1] Multiphoton Scattering Tomography with Coherent States, T. Ramos, and J.J. García-Ripoll, Phys. Rev. Lett. 119, 153601 (2017).

Friday 15. December 2017

Christmas market visit

 

Joint event with the hbar Omega Student Chapter

Meeting point: Entrance of the Neustädter Kirche

For more information: Please contact our student spokesperson