QST: Quantum Research Mobility

In our new paper titled Quantum researcher mobility: the wonderful wizard of Oz who paid for Dorothy’s visa fees, published in the IOP journal Quantum Science and Technology, we discuss the many hurdles facing international researcher mobility today. We tackle issues such as exorbitant visa fees, short-term contracts, and cultural hurdles to mobility. Most importantly, we discuss many examples of good practice from around the world and propose possible solutions to overcome such hurdles. This work was done in collaboration with Eliza Agudelo from TU Vienna and Ravi Kunjwal from Université libre de Bruxelles.

BBQLab @ ICOAM2022

Tampere, Finland at 11:30 PM!

Natalia and Mehul recently represented BBQLab at the 6th International Conference on Optical Angular Momentum in Tampere, Finland. It was a fantastic event, bringing together a diverse group of researchers from around the world working on structured photons, electrons, ions, and neutrons! Natalia won the second prize in the hotly contested ICOAM poster competition for her submission on entangled ripples and twists of light. Mehul presented an invited talk on our recent work on programming high-dimensional quantum optical circuits inside a complex medium. We are looking forward to ICOAM2024 in South Africa!

Congratulations to Natalia for winning 2nd prize in the ICOAM poster competition!
One of the many beautiful lakes around Tampere (photo taken from the Viikinsaari island, venue for the ICOAM conference dinner)

arXiv: Programming quantum circuits in a complex medium

Experimental setup and results for a five-dimensional discrete Fourier gate

In a recent paper on the arXiv, we show how high-dimensional quantum optical circuits can be programmed inside a commercial multi-mode fibre through the use of inverse-design techniques. Using these methods, we were able to demonstrate the transport, manipulation, and measurement of high-dimensional photonic entanglement by using the transmission channel itself!

We also present numerical results on the scalability of our approach, showing how the resource of a high-dimensional mode-mixer allows perfect and lossless circuits to be realised in principle. By harnessing something as simple as light scattering inside a multi-mode fibre, our work serves as a new, yet practical alternative to integrated photonic platforms.

This work was done in collaboration with our QuantERA project partners Claudio Conti (La Sapienza, Rome) and Pepijn Pinkse (Uni Twente, Netherlands). We look forward to many more exciting collaborations in the future!

Journal of Optics : Entangled ripples and twists!

Artist’s depiction of entangled Laguerre-Gaussian modes in 43 dimensions

In a recent article published in IOPscience Journal of Optics (Emerging Leaders Special Issue) we demonstrate the full-field entanglement of radial (ripples) and azimuthal (twists) Laguerre-Gaussian modes of light. While the azimuthal degree-of-freedom has attracted a lot of interest over the past two decades, the radial degree-of-freedom presents some unique challenges to experimentalists.

By carefully tuning our optical system parameters and adopting some recently developed techniques for precise spatial mode measurement, we generated and measured entanglement in a 43-dimensional radial and azimuthal LG mode space. We also studied two-photon quantum correlations between 9 LG mode groups, which are of significant interest in the field of fibre optics.

Science Advances: Quantum Conference Key Agreement

Most of us have spent an inordinate amount of time over the past year in online conference calls, which are sure to become a regular feature in our lives. Recent events such as the ransomware attacks on US energy firms have highlighted more than ever the need for information security in such electronic forms of communication.

In a collaboration with the Mostly Quantum Lab at Heriot-Watt, we demonstrated the first quantum-secure conference call between four users. Using a multi-photon entangled GHZ state distributed over fiber-optic cables with a combined length of 50km, we built a secure key between four parties and used it to share an image of the Cheshire cat. It won’t be long before the first quantum-secure Zoom call!

See the original publication in Science Advances or media coverage in the journal Nature and Physics World magazine for more details.