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.