Deep learning optimized single-pixel LIDAR

Hello all!

The first Seminar of the year will be given by Steven Johnson on the topic of Deep learning optimized single-pixel LIDAR on 15:00 on  Thursday 13/02/2020 in room 312.

Here is the abstract:

Light detection and ranging (LIDAR) systems have become a key technology for self-driving vehicles, with depth information typically gained through time-of-flight measurements. Single-pixel imaging can take pictures without using a pixelated array like a CCD. The single-pixel imaging also allows a choice of sampling basis, an optimised sampling basis was developed via deep learning to speed up the measurement process. By combining LIDAR with the optimised single-pixel imaging technique a better depth and intensity measurement can be made when using photon-counting detectors.

Snacks will be provided in the common room afterwards.

Cheers,
Kyle

The last Optical Sciences Seminars of the year

Hello everyone!

With the next week being the last week before the holidays, why not get out of the lab with two interesting seminars, to be followed with festive treats.

On Tuesday, Gregory Chaplain from Imperial College London is visiting University of Glasgow and will give a seminar titled "Good Vibrations: Controlling Waves, from Elasticity to Electromagnetism". Abstract

On Thursday, Rachel Offer of the Optics Group will give a talk titled "Atomic vapour wave mixing and structured light". Abstract

Gregory will give his talk at 14:00 on 17/12/19 in Kelvin 222.

Rachel will give her talk at 15:00 on 19/12/19 in Kelvin 222.

Festive treats will be provided in the common room afterwards where on or off topic discussion can continue over some festive treats!

I hope to see you all there,
Kyle

Quantum Gyroscope: using Hong-Ou-Mandel interference to test the role of relativity in quantum mechanics

Hello all!

This weeks Optical Sciences Seminar will be given by Sara Restuccia. The talk is titled "Quantum Gyroscope: using Hong-Ou-Mandel interference to test the role of relativity in quantum mechanics", and will be given on 7th November at 15:00 in room 222.

Abstract:

We test the role of relativity in quantum mechanics by studying the behaviour of entangled photons in a noninertial reference frame, in our experiment a rotating platform. Hence, we set up a fibre gyroscope, where two counterpropagating waves interfere at a common beamsplitter. Classically, this results in interference fringes which shift when the interferometer is rotated, in a phenomenon known as the Sagnac effect. In a nonclassical system, the interference of two entangled photons at a beamsplitter produces a phenomenon known as the Hong-Ou-Mandel effect (HOM). Here, a characteristic HOM dip in the coincidences of the detected photons is observed when the photons are indistinguishable. By setting our HOM on a rotating platform we were able to measure a shift in the position of the HOM dip as a function of the rotation speed. This relative delay in the photons arrival is equivalent to the classical Sagnac effect with the sole difference being that while in the classical set-up the rotation motion induces a change in the interference of the two beams, in the quantum set-up the change is in the quantum interference of the two photons.


Snacks will be provided in the common room after the talk!
Kyle

Implementing LiDAR spoofing using single Pixel Imaging and Optical delay lines

Hello all!

This weeks Optical Sciences Seminar will be given by Ahmed Elmubarak. The talk is titled "Implementing LiDAR spoofing using single Pixel Imaging and Optical delay lines", and will be given on 26th September at 15:30 in room 222. Please make note of the change of time and room. This is due to demonstrating schedules and the SUPA lecture series has started for this semester.

Abstract:

LIDAR is an indispensable sensor technology – along with other sensors- for autonomous vehicles which operates by scanning a pulsed light source and measuring the time of arrival of reflected light on a detector, whereupon the distance to objects is calculated from the time-of-flight (Δd = cΔt/2). We’ll explore the idea of spoofing A LiDAR system (in this case built using Single Pixel Imaging camera) into seeing simulated 3D virtual reality scenes. This technology, once realized can be used for testing integrated LiDAR system in autonomous vehicles without having to hack into the car system. The talk will have an introduction to Single Pixel Imaging and LiDAR technology.


Snacks will be provided in the brand new common room after the talk!
Kyle

From atomic magnetometry to image memory

HI all,

The second Optics Group Optical Sciences Seminar will be given by Francesco Castellucci. The talk is titled "From atomic magnetometry to image memory", and will be given on 18th July at 15:00 in Kelvin Room 222.

Abstract:

The spherical orientation of a magnetic field can be seen through the interaction between light with Orbital Angular Momentum (OAM) and a cold atomic cloud. Applying two vector vortex beams to a cloud of atoms, the azimuth angle of the magnetic field is seen in the linear rotation of the transmitted pattern, and the inclination is reflected in a fracturing of the observed image. Using a similar setup it should be possible for any kind of complex beam to be stored in the magnetic dipoles of the atoms.

Unfortunately I cannot make it. However, Sara Restuccia will host the Seminar and provide snacks in the common room afterwards.

Kyle

Bell inequality in full field images of spontaneous parametric down-conversion

Hello Everyone!

I hope you are having a great summer so far. This weeks Optical Sciences Seminar will be given by Paul-Antoine Moreau of the Optics Group. The talk is titled "Bell inequality in full field images of spontaneous parametric down-conversion", and will be given on 4th July at 15:00 in Kelvin Room 312.

Abstract:

We use an imaging setup based on heralded imaging to test a Bell-CHSH inequality within images. Based on a single full-field image accumulated by summing camera frames we find that the Bell inequality is violated.

Loophole free demonstrations of Bell non-locality have been performed recently. But testing Bell inequalities in new domains remains an objective of importance given the very pivotal role that Bell non-locality could play within the emergence of quantum technologies. We report on an attempt at performing such a demonstration in the context of quantum imaging.

With the common room still out of action snacks will be provided outside Room 312 when the talk finishes.

See you there!
Kyle

Hi all, 

The next Optical Sciences seminar will be given by Neel Mackinnon from the Quantum Theory group at 3pm on Thursday 9th May in 222. Neel will be presenting the following: 

Title: Electromagnetic Helicity within a Chiral Medium

Abstract: The electromagnetic helicity is a locally conserved quantity of the free electromagnetic field which, in a sense, describes the “handedness” of the field. The name “helicity” can be justified by the fact that the total helicity of an electromagnetic field, integrated over all space, is proportional to the difference in the number of left- and right-handed circularly polarised photons in the field. The concept of helicity can also be made meaningful in presence of matter – in this case it is no longer conserved, but charges and currents may act as sources or sinks of helicity. The definition of helicity can then be very straightforwardly extended to apply within dielectrics. 

However, this straightforward extension runs into difficulties if the dielectric material is chiral (that is, if it can exhibit optical rotation). This talk will introduce some of the features of electromagnetic helicity, and describe a proposed modification to the definition of the helicity density within a chiral medium.

The talk will last around 20 minutes, followed by coffee and biscuits in the common room. 

Hope to see you there,

Frances 

Optical angular momentum transfer on total internal reflection

Hi all,

The next seminar will be held this Thursday 25th April, 3.30 pm, Kelvin Building lecture theatre 257, with Atirach Ritboon from the Quantum Theory group.

Abstract:

1. We study the mechanism of optical angular momentum transfer from light to a dielectric medium on total internal reflection. We employ a quantized approach and, in particular, work with a single-photon pulse. This allows us to evaluate the force and torque per photon and also, crucially, to evaluate forces and torques conditioned on transmission or reflection at an interface. The reflected electric and magnetic fields of an incident paraxial beam carrying orbital and spin angular momentum are obtained using an angular spectrum method. We calculate the expectation value of the single-photon torque exerted on the dielectric, due to total internal reflection of a single-photon pulse, using the dipole-based Lorentz force density. We apply this result to describe the angular momentum transfer from light on passing through an M-shaped Dove prism. 

Hope to see you there, and for coffee and biscuits in the common room afterwards,

Frances

Adaptive Prospective Optical Gating Allows 4D Imaging and Quantification in the Developing Zebrafish Heart

Next seminar this Thursday 11th April, 4pm, room 222 Kelvin Building, this time with Chas Nelson from the Imaging Concepts Group!

Title:

Adaptive Prospective Optical Gating Allows 4D Imaging and Quantification in the Developing Zebrafish Heart.

Abstract:

Researchers interested in the heart have long used a wide range of imaging techniques to see, understand and quantify changes throughout heart development, repair and, in certain species, regeneration. Two major challenges in imaging the heart are the contrasting problems of high-frequency heart beating and low-frequency morphological changes. I will demonstrate how using our established method of prospective optical gating, in combination with light-sheet microscopy, can allow the synchronised capture of 3D images of the in vivo beating zebrafish heart. However, prospective optical gating alone is limited to snapshots of the heart at chosen target heartbeat phases and only over the scale of tens of minutes.
We have now developed adaptive prospective optical gating technologies that we are using in combination with light-sheet microscopy to enable a range of 3D+time and 3D-timelapse imaging experiments. Our adaptive prospective optical gating technology allows us to carry out 48+ hour, in vivo, 3D-timelapse imaging of the computationally 'frozen' heart across developmental stages, e.g. heart looping, and throughout injury response and repair. Imaging across these timescales is not possible with prospective optical gating alone and phase-locked timelapse imaging is not possible using retrospective optical gating alone: only with our hybrid system are such longitudinal studies possible. Our hybrid prospective-retrospective optical gating system allows researchers to study and understand cardiac development and repair without the use of chemicals or optogenetics to stop or modify the natural heart beating.

Hope to see many of you there,
Cheers,
Chiara.

Extended-depth point localisation microscopy using Airy-beam-based point-spread functions

Hi all!

Imaging Concepts Group's turn this week at the Optical Seminar, with Zhuang taking a break from his thesis to tell us about some of his PhD work:

Title: 

Extended-depth point localisation microscopy using Airy-beam-based point-spread functions

Abstract:

The precise localisation of point sources in optical microscopy enables nm-resolution imaging of single-molecules and biological dynamics. Existing approaches for point localisation, however, suffer from the very limited depth range and thus not suitable for imaging thick samples. We utilise the lateral translation property and the diffraction-free propagation of Airy-beam-based point-spread functions to localise point emitters in 3D space with the key advantages of extended depth range, higher optical throughput and potential for imaging higher emitter densities than are possible using other techniques. The proposed techniques are demonstrated for blood-flow imaging in a live zebrafish. 

Thursday 4th of April, 4pm, room 312 Kelvin Building.

As usual, snacks and soft drinks in the common room afterwards :)

Hope to see many of your there,

Cheers,

Chiara.

Portable, real-time, methane-imaging camera

Hello everyone!

This weeks Optical Sciences Seminar will be given by myself on my work developing a gas imaging camera. I will give a short presentation on the device and then do a live demonstration!

The seminar will take place on Thursday 14th March in Kelvin 222 at 16:00.

Snacks will be provided in the common room afterwards, where discussions can take place.

In the meantime I hope these images whet your anticipation.

Cheers,
Kyle

The output of the portable, real-time, methane-imaging camera. Methane is highlighted in a green false coloured overlay. The gas cells are 10mm thick and the tube is releasing a low pressure methane cloud

The portable, real-time, methane-imaging camera without its housing

Optical Simulation of a Quantum Particle Living on a Surface of a Tetrahedron

Hello all!

The first of the Optics Group's Seminars will be by Jakub Belin who will give a talk titled "Optical Simulation of a Quantum Particle Living on a Surface of a Tetrahedron".

The talk will take place on 28th February at 16:00 in Kelvin 222.

Abstract:

We analyze propagation of waves on the surface of the simplest Platonic solid, the regular tetrahedron.  We find the time evolution of a quantum particle confined to such a surface is completely analogous to the diffraction pattern from a certain grating profile, and can therefore be investigated in a simple diffraction experiment.  The quantum particle exhibits perfect quantum state revivals, which translate into the fractional Talbot effect in the equivalent diffraction experiment.  We present the results of such an experiment and compare them with numerical simulations.

As usual, snacks will be provided afterwards in the common room. I hope to see you there!

Cheers,
Kyle

Skyrmion structure in vector beams

Hi everyone, 

The first talk of the year will be given on Thursday 17th January by Scarlett Gao from the Quantum Theory group on the following: 

Skyrmion structure in vector beams
Vector beams have both a spatially varying amplitude and polarization, for light, or spin direction for electrons.  Associated with these we find a topological feature, the skyrmion number, that it is robust against any deformation during propagation. The simplest way to map out this feature is to use the associated skyrmion field.  This is a transverse or divergenceless field and so has neither sources nor sinks.  Mapping out the skyrmion field for these beams reveals constraints on the manner in which vector beams can be manipulated.

The talk will begin at 4pm in lecture theatre 312 and will last around 20 minutes. This will be followed by refreshments in the common room. 

Hope to see you there!

Frances 

Quantum eavesdropping strategies

Hi everyone,

The last talk of the year will be given by Kieran Flatt from the Quantum Theory group, on quantum eavesdropping strategies.

Abstract:
Quantum key distribution is a method for sharing cryptographic keys and which uses the active nature of quantum measurements to flag eavesdropping to the legitimate users. I'll present two schemes, the well-known BB84 and lesser explored PCB00, and explain what the best eavesdropping strategies are in each case.

The talk will be on Thursday 6th December at the usual time of 4pm in 257.

Join us afterwards in the common room for some mulled wine and suitably festive treats! 

Frances 

Compressive light-sheet microscopy by Chiara Garbellotto

Hello everyone,

Chiara will be our next presenter at the optical sciences seminars. She will talk about her work on light-sheet microscopy: "I'll summarise what I've done so far during my PhD and talk about what I'm working on at the moment (tiling light-sheet, z-compressed light-sheet), hoping to get some inspiration/suggestions/advice."

Check out a 3 minute thesis winning video by Chiara for a very cartoon-y intro to light-sheet microscopy  https://www.youtube.com/watch?v=7WM8D_A4leY

Please note that there is a change in venue and time.

Date: Thursday 22nd November
Time: 16:30
Venue:  Room 255A SUPA VC room

We will be having some mulled wine and mince pies after the talk in the common room. See you all there! :)


Cheers,
Pavi.

Computational imaging in infrared domain using multiple cameras and more..

Hello everyone!


It's Imaging concepts group's turn to present this week. Dr. Miguel Preciado will be presenting his research on building low-cost infrared camera arrays for enhanced capabilities such as Integral (light-field) imaging, Pixel super-resolution, and multi-spectral imaging. Click here for more details on the topic.


Date: Thursday 8th November
Time: 16:00
Venue:  Room 257

Snacks will be provided in the common room after the seminar.

Cheers,
Pavi.

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.