past events

Thursday 29. March 2018

IMPRS monthly meeting

 

Organisation: Ramin Beravat (MPL/ Russell Division)

What: Talk about "How to find a job" by Ramin

Where: MPL, Library (room 2.500, 2nd floor)

Friday 23. March 2018

LECTURE ANNOUNCEMENT
Dissipation of multi-partite systems under structured environments

 

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

Speaker: Fernando Galve (Institute for Interdisciplinary Physics and Complex Systems, IFISC (CSIC-UIB))

Place: MPL / library (2.500)

Abstract:

We first review the transition of collective to separate (or local) dissipation in multi-partite systems under structured environments. Introducing a microscopic model of environment such as a periodic lattice, the transition is seen to be governed by the cross-damping coefficient, which can display long-range isotropic, directional long-range (dependent on crystal symmetry axes and orientation), and short-range behaviors depending on resonance conditions, but never on the bath's correlation length. We also find a frequency cutoff dependent only on system size. Next, we translate this scenario to atoms radiatively coupled through 2D photonic crystals, showing that purely directional emission is possible from FDTD simulations. We use this behavior, together with recently introduced reflective boundaries, to show how a variety of dark states of many atoms can be built. Finally we comment on recent results where we show that purely coherent directional interactions can be designed.

 

 

 

 

 

Monday 12. March 2018

LECTURE ANNOUNCEMENT
Squeezing vacuum with Rb atoms: quantum enhanced magnetometry and competition of spatial modes

 

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

Speaker: Prof.  Eugeny Mikhailov (Department of Physics College of William & Mary Williamsburg, USA)

Place: MPL / seminar room 1.500

Friday 23. February 2018

LECTURE ANNOUNCEMENT
Digital electronic analysis, synthesis, and manipulation of the full optical field

 

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

Speaker: Dr Peter Winzer, Director (Optical Transmission Subsystems Research, NOKIA Bell Labs, Crawford Hill, USA)

Place: MPL / seminar room 1.500

Abstract:

Optical communication systems have seen fundamental technological changes over the past 10 years that have completely redefined our ability to analyse, synthesize, and manipulate optical fields across all their physical dimensions: time/frequency, quadrature, polarization, and spatial mode content. State-of-the-art optical capabilities include stable low-linewidth lasers, programmable GHz-resolution optical filters, and spatial light modulators. Electronics capabilities include digital coherent subsystems based on high-speed (up to 100-GHz) analog-to-digital and digital-to-analog converters, and digital electronic signal processors based on Field Programmable Gate Arrays that can handle a Tbit/s of real-time data. These capabilities are about to fundamentally blur the boundaries between optical and electronic signal processing, asking for a combined view on optics and high-speed digital electronics in the analysis, synthesis, and manipulation of the full optical field, and enabling radically new opportunities across a wide range of photonics disciplines. After reviewing modern digital coherent detection and space-division multiplexing using multiple-input-multiple-output (MIMO) processing to scale fiber-optic network capacities, with new levels of physical-layer security as a by-product, we will take a glimpse at the vast possibilities enabled by fully digital light manipulation outside of telecom, from optical coherence tomography to endoscopic imaging to arbitrarily nonlinear and time-variant interferometry to ultra-fast optical tweezers.

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.