Orbital Angular Momentum Reversal due to Extreme Doppler Shifts - Graham Gibson

Hello everyone!

Continuing the Optics Group's turn at hosting seminars will be Graham Gibson. The talk, titled Orbital Angular Momentum Reversal due to Extreme Doppler Shifts, will take place on Thursday 25th October at 16:00 in Room 257. The abstract is as follows:

The linear Doppler shift is familiar to everyone as the change in the observed frequency of an ambulance siren as it passes by. A less well known form is the rotational Doppler shift which is proportional to the relative rotation rate between source and observer, multiplied by the angular momentum carried by the beam. Using an acoustic source of orbital angular momentum we can demonstrate an extreme Doppler shift that is larger than the rest-frame frequency, resulting in the observed frequency becoming negative in the case of a red shift. The emergence of negative frequencies in physical systems is often accompanied by intriguing consequences. For the linear case this is associated with a time reversal of the received signal. For the rotational case it is associated with a handedness reversal of the detected orbital angular momentum.

Snacks will be provided in the common room after the seminar and once again Curler's Rest has been nominated as a pub where discussion can continue after work.

Kyle

The applications of single-pixel imaging - Steven Johnson & Yiwei Zhang

Hello everyone!

This weeks Seminar will be given by Steven Johnson & Yiwei Zhang on The applications of single-pixel imaging. The talk will take place on Thursday 11th October at 16:00 in Room 257. The abstract is as follows:

Single-pixel imaging enables the photography of phenomena that would be impossible with a traditional camera. Most images are captured with pixelated-arrays such as a CCD or CMOS sensors; whereas single-element detectors can be manufactured to be sensitive to unusual wavelengths, outside the visible spectrum, or have very fast response times. By using a detector with high temporal resolution, events occurring on the order of nanoseconds can be imaged. Using a digital micro-mirror device and a pulsed laser we have applied single-pixel imaging methods to many applications, these include: 3D videos of a scene, imaging the light-in-flight, fluorescence lifetime imaging and duel-band astronomy.

Snacks will be provided in the common room after the seminar and once again Curler's Rest has been nominated as a pub where discussion can continue after work. Turnout was great two weeks ago so I look forward to seeing people there again!

Kyle.

Imaging with Quantum Entanglement - Christy Simpson

A little late updating the blog.... but the last seminar was given by Christy Simpson, one of the PhD students in the Extreme Light group.  He was talking about our recent work on imaging entangled photons pair using metasurfaces. The talk was based on our arXiv paper which can be found at: https://arxiv.org/abs/1805.01713.

Abstract:
Quantum entanglement is a key resource that can be exploited for a range of applications such
as quantum teleportation, quantum computation and quantum cryptography. However, efforts
to exploit entanglement in imaging systems have so far led to solutions such as ghost imaging,
that have since found classical implementations. Here we demonstrate an optical imaging protocol
that relies uniquely on entanglement: two polarising patterns imprinted and superimposed on a
metasurface are separately imaged only when using entangled photons. Classical light is not able to
distinguish between the two patterns. Entangled single photon imaging of functional metasurfaces
promises advances towards the use of nanostructured subwavelength thin devices in quantum information protocols and a route to efficient quantum state tomography.

What is the point of boson sampling? - Thomas Brougham

Hello everyone,

This week's presenter is Thomas from Quantum Theory group. Please find details of the talk below:

Title: What is the point of boson sampling?
Time: 3pm on 30th August 2018
Venue: 257 Kelvin Building

Abstract:

In principle, quantum computers could provide an exponential speed-up on certain problems.  This would mean that problems which are currently intractable could be solved efficiently.  For example, one could quickly find the prime factors of extremely large numbers and thus crack RSA cryptography.

While this should work in principle, we don’t have any evidence that such exponential speed-ups would ever be possible in practice.  Realistic experimental situations could render this quantum advantage negligible for interesting problems.  It is for this reason that there is a great interest to show that an exponential quantum advantage can be realized in an experiment.  However, building a full quantum computer is rather difficult.  A simpler approach is to build an optical experiment that efficiently solves one single problem.  This is the idea behind boson sampling, which uses light within a passive linear optical network.   A full experimental demonstration of boson sampling would prove that quantum systems really can efficiently solve seemingly intractable problems.

Realizing a demonstration of boson sampling would be a great technical achievement.  However, the boson sampling problem is not very interesting in of itself.  In this talk I will argue that boson sampling could be used for other tasks.  For example, it can be used within cryptography and to help simulate the dynamics of certain quantum systems.  This would mean that while a boson sampler is not a full quantum computer, it could still have some applications.

See you all there!

Pavi.

Stuart Wilson on Computational imaging techniques in Micro-endoscopy

Hi all,

This week's talk will be presented by Stuart Wilson, a PhD student from the imaging concepts group. Stuart will be talking about his research on exploiting computational imaging methods to extend the depth-of-field and field-of-view in GRIN based micro-endoscopes. Details below:

Title: Advanced and Computational Imaging Techniques in Microendoscopy

Time and Venue: 3pm, Thu 9th Aug, 257 Kelvin Building

Abstract: The developing field of microendoscopy has the potential to overcome many of the risks associated with current approaches in clinical tissue characterisation and histology. These miniature optical devices enable deep tissue imaging at penetration depths of tens of millimetres – a technique known as optical biopsy – and can reduce the need for invasive surgical procedures. However, the miniaturisation of optical elements provides its own set of unique challenges, effectively degrading imaging performance by imposing a characteristically short depth of field, narrow field of view and a high affinity to optical aberrations. Using computational imaging techniques, we have demonstrated an order of magnitude increase in the depth of field, as well as a wider field of view and reduction in the intrinsic aberrations, resulting in a more robust optical probe for tissue characterisation.

See you all there!

Cheers,
Pavi.

Research in the Imaging concepts group

Hello everyone,

This week it is the Imaging Concepts Group's turn to give a peek into the research conducted in their labs. Andy, leader of the group, will present an overview of the research conducted mainly in the areas of computational imaging, multi-spectral imaging, infrared imaging, retinal imaging and in vivo imaging of rodents. Jonny will then takeover to tell us about the exciting research under his supervision on light-sheet microscopy and 3D imaging of a beating Zebrafish heart.

Link to the group's webpage: https://www.gla.ac.uk/schools/physics/research/groups/imagingconcepts/

See you all there!

Pavi.

Summary of weeks 2-4

Hi all,

It has been very interesting past few weeks with Vincenzo presenting his work on near zero refractive index materials on week 2 and Matt, Neal, Euan presenting the overview of the research conducted in the Optics group on weeks 3 and 4. Matt covered primary research interests of Miles, which included single pixel cameras, quantum gyroscope, imaging using entangled photon pairs for increased resolution and sub-shot noise imaging, optical trapping etc. Neal presented Sonia's research projects on Fresnel cones, talbot effect, vector beam shaping for STED type of microscopy and, trapping atoms and cooling them down to upto micro-Kelvin temperatures. Euan gave an overview of Johannes's research which focused primarily on building telescopic windows using lenslet-array pairs to build low-vision aids.

We had a steady attendance of over 40 in every talk and we hope to see similar attendance in future and looking forward to see many more interesting talks in the coming weeks.

Also, we have started sharing the presentations from our colloquia at:  https://www.slideshare.net/UOGOptics. The presentations on research groups' overview talks are currently being uploaded. Uploading presentations will be optional for the presenters so not all the presentations will be available, but we will try to make as many available as possible.

For now, some snapshots from the past few week.. Ciao Adios!