Colloquium SS 22

Colloquium: Sommersemester 22

COLLOQUIUM TALK LIVE STREAM

The talk will be streamed via zoom and can be accessed through the link below

> 17:15 Get-Together, Coffee & Snacks
> 17:45 VCQ Student talk
> 18:00 Main Talk

All Talks will be held at the Main Lecture Hall at TU Wien, Atominstitut, Stadionallee 2, 1020 Vienna.
Please note the actual Covid rules at the Atominstitut. Don’t forget to wear a FFP2 mask and to keep a 1-meter-distance during the get-together with coffee and snacks.

INFORMATION

Date	Speaker	Affiliation	Talk
21.03.2022	Andreas Nunnenkamp	University of Vienna	Novel Platforms for Quantum Science and Technology
25.04.2022	Monika Ritsch-Marte	Medical University of Innsbruck	Generally applicable technique for measuring optical force and torque acting on trapped particles
30.05.2022	Daniele Faccio	University of Glasgow	Photon pair correlations: from imaging to spacetime entanglement
13.06.2022	Kirk W. Madison	University of British Columbia	A Quantum Sensor for Vacuum Metrology

21. March 2022

Andreas Nunnenkamp (University of Vienna)

Novel Platforms for Quantum Science and Technology

The 'second quantum revolution' aims at exploiting coherence for novel technologies that will likely
involve electromagnetic, mechanical, atomic, and topological degrees of freedom.
Directional amplifiers, that amplify signals depending on the propagation direction, have recently attracted much attention, also for applications in quantum technologies. Here, I will present a unifying framework based on topology to understand non-reciprocity and directional amplification in driven-dissipative cavity arrays. Specifically, I will discuss a one-to-one correspondence between a non-zero topological invariant defined on the spectrum of the dynamic matrix and regimes of directional amplification, in which the end-to-end gain grows exponentially with the number of cavities.
Time permitting, I will give a brief overview on our work on higher-order and fractional discrete time crystals in quantum and classical spin arrays.

25. April 2022

Monika Ritsch-Marte (Medical University of Innsbruck)

Generally applicable technique for measuring optical force and torque acting on trapped particles

Optical tweezers have become so successful, because their application goes beyond simply holding or moving particles, as they provide quantitative information on the optical forces acting on the particle. It will be shown how a holographic, i.e. phase-sensitive, measurement of the light scattered by the particle interfering with the incident trapping beam directly deliver the local forces. It is possible to simultaneously measure all components of the force applied to an individual particle in a trapped ensemble, or to a specific site of an extended object. Here, conservation of optical momentum is exploited. The approach may also be modified to measure the optical torque, based on conservation of optical angular momentum. The torque pertaining to individual particles is accessible, as well as separate spin or orbital parts of the total torque. The examples which will be discussed feature micron-size objects in liquid solution, but the technique is not limited to this type of biomedical setting, but may also be used in vacuum.

30. May 2022

Daniele Faccio (University of Glasgow)

Photon pair correlations: from imaging to spacetime entanglement

Entangled photon pairs are the workhorse for most quantum photonics research
labs.

Compared to other quantum technologies, photon pairs are easy to generate, they
are cheap, they can be plentiful, they are relatively easy to detect and the techniques
developed to detect them find applications in many other areas ranging from lidar
to new computational imaging approaches.

I will give a brief overview of some of our work in these fields, starting from photon-pair inspired imaging techniques that rely on the ability to efficiently detect the spatial correlations between entangled photon pairs. Examples are a new form of quantum holography and quantum microscopy based on Hong-Ou-Mandel interference, i.e. the coalescence of photons at a beamsplitter.

I will then show how we are using HOM interference to investigate the interplay of non-intertial motion, i.e. rotation and entanglement.

13. Juni 2022

Kirk W. Madison (University of British Columbia)

A Quantum Sensor for Vacuum Metrology

The development of atom based clocks has revolutionized time and frequency standards. In addition, atoms have been used to realize exquisitely sensitive accelerometers, gravimeters, and magnetometers as well as EM wave detectors and quantum transducers. In this talk, we will review the use of ensembles of single atoms for vacuum metrology. Notably, we show that an atom is a self-calibrating quantum sensor that makes possible accurate pressure and flux measurements for any species in the ultra-high pressure regime (<10e-7 Pa).